International comfort products Fem4 Installation and user guide

496 08 8001 00 2/17/2014

Specifications subject to change without notice.

FEM4, FCM4, FSA4, FEA4, FSM4, FSU4, FXM4, FVM4, FMA4,

WAH, WAP, WAM, WAX, REM4

SERVICE AND MAINTENANCE INSTRUCTIONS

VERTICAL/HORIZONTAL/MULTI−POSITION FAN COIL UNITS

NOTE: Read the entire instruction manual before starting the

installation.

TABLE OF CONTENTS

PAGE

SAFETY CONSIDERATIONS 1........................

INTRODUCTION 1..................................

FAN COIL DESCRIPTION AND TROUBLESHOOTING 1..

FSM4P, FSU4P, FSM4X, FSU4X, FSA4X 1............

FEM4P, FEM4X, FXM4X, FEA4X, WAHA, WAPM,

WAPT, WAPL, WAHM, WAHT, WAHL, WAXM,

WAXT, WAXL, REM4P, REM4X 5....................

FVM4X 6.........................................

FCM4X 12........................................

FMA4P, FMA4X, WAMA WAXA 17...................

ELECTRIC HEATER FUNCTION

AND TROUBLESHOOTING 21........................

FEM4, FCM4, FSA4, FEA4, FXM4, FVM4, WAPM,

WAPT, WAPL, WAHM, WHAT, WAHL, WAXM,

WAXT, WAXL, REM4 21............................

FMA4, WAMA, WAXA 21............................

CARE AND MAINTENANCE 22.......................

FEM4P, FEM4X, FCM4X, FXM4X, FVM4X, WAHA,

WAPM, WAPT, WAPL, WAHM, WAHT, WAHL,

WAXM, WAXT, WAXL, REM4X 22....................

FSA4X, FEA4X, FMA4P, FMA4X, WAMA, WAXA 23....

REFRIGERANT FLOW−CONTROL DEVICE 24..........

Thermostatic Expansion Valve (TXV) 24...............

Piston Body Cleaning and Replacement 25............

COIL & CONDENSATE PAN REMOVAL

and REPLACEMENT 25..............................

R−410A QUICK REFERENCE GUIDE 27...............

SAFETY CONSIDERATIONS

Improper installation, adjustment, alteration, service,

maintenance, or use can cause explosion, fire, electrical

shock, or other conditions which may cause death, personal

injury or property damage. Consult a qualified installer,

service agency, or your distributor or branch for information or

assistance. The qualified installer or agency must use

factory−authorized kits or accessories when modifying this

product. Refer to the individual instructions packaged with kits

or accessories when installing.

Follow all safety codes. Wear safety glasses, protective

clothing and work gloves. Have a fire extinguisher available.

Read these instructions thoroughly and follow all warnings or

cautions included in literature and attached to the unit.

Consult local building codes and the current editions of the

National Electrical Code (NEC) NFPA 70.

In Canada, refer to the current editions of the Canadian

Electrical Code CSA C22.1.

Recognize safety information. This is the safety−alert symbol

. When you see this symbol on the unit and in instruction

manuals, be alert to the potential for personal injury.

Understand the signal words DANGER, WARNING, and

CAUTION. These words are used with the safety−alert

symbol. DANGER identifies the most serious hazards which

will result in severe personal injury or death. WARNING

signifies hazards which could result in personal injury or

death. CAUTION is used to identify unsafe practices which

may result in minor personal injury or product and property

damage. NOTE is used to highlight suggestions which will

result in enhanced installation, reliability, or operation.

UNIT OPERATION AND SAFETY HAZARD

Failure to follow this caution may result in equipment

damage, improper operation or personal injury.

When coils are pressurized with nitrogen, open the

suction port first to release the nitrogen. Mesh screens

may dislodge if the liquid line is opened first.

!CAUTION

UNIT OPERATION AND SAFERTY HAZARD

Failure to follow this warning could result in personal

injury or death.

R−410A systems operate at higher pressures than R−22

systems. Do not use R−22 service equipment or

components on R−410 equipment. Ensure service

equipment is rated for R−410A.

!WARNING

INTRODUCTION

These fan coil units are designed for flexibility in a variety of

applications that meet upflow, horizontal, or downflow

requirements. Units are available in 1−1/2 through 5 ton

nominal cooling capacities. Factory−authorized,

field−installed electric heater packages are available in 5kW

@ 240Vac through 30kW @240Vac.

ELECTRICAL OPERATION HAZARD

Failure to follow this warning could result in personal injury

or death.

Before installing or servicing unit, always turn off all power

to unit. There may be more than one disconnect switch.

Turn off accessory heater power if applicable. Lock out

and tag switch with a suitable warning label.

!WARNING

SERVICE AND MAINTENANCE FAN COILS

2496 08 8001 00

Specifications subject to change without notice.

FAN COIL DESCRIPTION

AND TROUBLESHOOTING

PSC FAN MOTOR

FSM4, FSU4, FSA4

The PSC motor is two or three speed direct drive.

High−speed lead is black, low−speed lead is red, and

common lead is yellow. Be sure proper blower speed has

been selected..

The motor is turned on through two different routes. The first

occurs when thermostat calls for the fan in cooling, heat

pump, or fan−only mode. A 24−Vac signal is sent to relay,

causing relay to close its normally open contacts, turning fan

on.

The second occurs when there is a call for electric heat. A

24−Vac signal is sent to heater sequencer/relay, causing it to

close, directing 230V through the normally closed contact of

fan relay, turning fan on. The fan remains on until

sequencer/relay opens.

If motor does not run, test motor for an open winding or a

winding shorted to motor case. If either is present, replace

motor.

ELECTRIC HEATER SERVICE

Service can be completed with heater in place. Shut off

power before servicing.

A. Limit Switch

Refer to Electric Heater Function and Troubleshooting section

of this manual.

B. Sequencer

Refer to Electric Heater Function and Troubleshooting section

of this manual.

C. Transformer

A 40−VA transformer supplies 24−V power for control circuit.

Check for 208/230V on primary side of transformer. If present,

check for 24V on secondary side.

NOTE: Transformer is fused. Do not short circuit.

D. Fan Relay

Relay coil is 24−V. Check for proper control voltage. Replace

relay if faulty.

CLEANING OR REPLACING REFRIGERANT

FLOW−CONTROL DEVICE

Refer to Figure 18 and instructions given in “Piston Body

Cleaning or Replacement” section.

The refrigerant flow−control device is protected by a wire

mesh strainer. It is located inside the 3/8−in. liquid tube at

field braze joint next to flow−control device. Access to strainer

is through field braze joint.

SEQUENCE OF OPERATION

A. Condensing Unit

COOLING

When thermostat calls for cooling, the circuit between R and

G is complete and single−pole single−throw relay FR is

energized. The normally open contacts close causing blower

to operate.

The circuit between R and Y is also complete. This

completed circuit causes contactor in outdoor unit to close

which starts compressor and outdoor fan.

HEATING

When thermostat calls for heating and FAN switch is set on

AUTO, the circuit between R and W is complete. The heater

sequence SEQ is energized which closes contacts of relay.

There will be a time delay. This completed circuit energizes all

heating elements HTR and blower motor.

B. Heat Pump

COOLING

On a call for cooling, the thermostat makes circuits R−O, R−Y,

and R−G. Circuit R−O energizes reversing valve, switching it

to cooling position. Circuit R−Y energizes contactor starting

outdoor fan motor and compressor. Circuit R−G energizes

indoor unit blower relay starting indoor blower motor.

When thermostat is satisfied, its contacts open de−energizing

contactor reversing valve and blower relay. This stops

compressor and fan motors.

HEATING

On a call for heating, the thermostat makes circuits R−Y and

R−G. Circuit R−Y energizes contactor starting outdoor fan

motor and compressor. Circuit R−G energizes indoor blower

relay starting blower motor.

Should temperature continue to fall, R−W circuit is made

through second−stage room thermostat bulb. Circuit R−W

energizes a sequencer bringing on supplemental electric

heat.

When thermostat is satisfied, its contacts open de−energizing

contactor and sequencer. All heaters and motors should stop.

Control Board (contact FAST for part number)

This section of the service manual describes the PCB by

examining the functional operation of the PCB components.

Printed Circuit Board (PCB) Component

Layout of the actual PCB is depicted in Figure 1.

1. The low−voltage stripped leads are used to connect

the 24−V side of transformer to indoor thermostat and

outdoor section.

2. A 5−amp fuse is used to protect the low−voltage

transformer secondary.

3. The fan relay is controlled by thermostat and turns fan

on and off.

4. A plug is used as the connection for PCB power and

electric heaters. Note the pin numbers on plug.

5. A time−delay relay circuit keeps fan motor running for

approximately 90 seconds after G is de−energized.

The time−delay can be defeated by cutting jumper

JW1.

Unit Functions

A. Transformer

1. Proper Wiring of Transformer Primary or High Side

Yellow wire from Molex plug is wired to C terminal on

transformer and black wire from PCB relay

(normally−open) terminal is wired to 208−V or 230−V

terminal on transformer. Units are factory wired at

230−V terminal.

2. Proper Wiring of Transformer Secondary or 24−V Side

Red wire of transformer is wired to T terminal on PCB

and brown wire of transformer is wired to C terminal on

PCB.

NOTE: T terminal on PCB is used to protect the transformer.

T terminal is connected through the fuse to R terminal on

PCB.

B. Indoor Fan

1. Wiring

Indoor fan motor yellow lead is wired to C terminal on

transformer. The red, blue, or black speed lead is wired

to SPT terminal on fan relay part of PCB. Units are

factory wired on medium speed (blue lead connected).

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 3

Specifications subject to change without notice.

NOTE: Unused fan speed leads must be capped or taped off

to prevent direct short to cabinet surface.

2. Functional Control

a. Thermostat and Relay Control

When thermostat calls for the fan in cooling, heat

pump, heating, or fan−only mode, a 24−Vac signal

is sent to relay. This causes the relay to close its

normally−open contacts, turning on fan. When

thermostat no longer calls for the fan, the signal

sent to relay is turned off and relay opens causing

fan to turn off after a 90−second fan−off delay.

b. Sequencer/Electric Heat Relay Interlock

The fan will also operate whenever there is a call

for electric heat, even if fan relay is not energized.

This happens because fan is interlocked with first

stage of electric heat through the normally−closed

contact of fan relay.

NOTE: The fan interlock is only connected to first stage

electric heat (W2). W3 and E do not contain an interlock with

fan. See outdoor thermostat installation instructions when

electric heat staging is desired.

C. Electric Heat

When thermostat calls for electric heat, a 24−Vac signal is

sent to sequencer/heat relay through W2, causing first stage

to turn on. W3 and E also receive signal if wired in with W2. If

W3 and E are not wired to W2, the sequencers/heat relays

can be controlled individually to stage additional electric heat.

The sequence control is described in the following section:

1. W2

When thermostat sends a signal to W2, a 24−Vac

signal is applied across sequencer/relay No. 1, causing

it to close. When sequencer/relay No. 1 closes, first

stage of electric heat is energized. In straight electric

heat, fan is also energized through the normally closed

contacts of fan relay. In cooling, heat pump, or manual

fan mode, fan will already be running since fan relay

would have been energized. When thermostat stops

calling for electric heat, the 24−Vac signal to

sequencer/relay No. 1 turns off and sequencer opens

after a delay of 60 to 90 seconds. Heaters equipped

with relays will be de−energized immediately. When

sequencer/relay opens, first stage of heat turns off

along with fan, providing thermostat is not calling for

the fan.

2. W3

When a signal is sent to W3, a 24−Vac signal to

sequencer/relay No. 2 causes it to close, with second

stage of electric heat turning on. The 24−Vac signal

applied to sequencer/relay No. 1 causes fan to

operate. Timing is such that sequencer/relay No. 1 will

turn on before sequencer/relay No. 2. When signal to

W3 is turned off, sequencer/relay No. 2 opens. If W2 is

also satisfied, first stage of electric heat and fan will

also turn off, providing thermostat is not calling for the

fan.

3. E

When thermostat sends a signal to E, a 24−Vac signal

is sent to sequencer/relay No. 3. The 24−Vac signal

applied to sequencer/relay No. 3 turns on third stage of

electric heat. The 24−Vac signal applied to

sequencer/relay No. 1 turns on first stage of electric

heat and fan. When thermostat stops calling for electric

heat, the signal to sequencers/relays 1, 2, and 3 are

turned off, and sequencers/relays open. This causes

electric heat to turn off with fan, providing thermostat is

not calling for the fan.

NOTE: Electric heaters are factory wired with all stages tied

together. If independent staging is desired, consult outdoor

thermostat installation instructions, or corporate thermostat

instructions.

TROUBLESHOOTING THE PRINTED CIRCUIT BOARD

Use wiring schematics shown in Figure 1 as a guide in

troubleshooting PCB unless otherwise noted.

A. If Fan Will Not Turn On from Thermostat:

IF THERE IS NO HIGH VOLTAGE TO TRANSFORMER:

1. Check plug/receptacle connection. This supplies power

from heaters to PCB Fan Relay. Be sure plug is

connected properly.

2. Check sequencer/relay No. 1 and plug wiring. Yellow

wire should be connected to Pin No. 9 of plug and to

limit switch. Black wire should be connected to Pin No.

7 of plug and to sequencer/relay No. 1.

3. Check field power leads L1 and L2. If these are not

receiving power, system cannot function.

IF TRANSFORMER HAS HIGH VOLTAGE APPLIED TO IT:

1. Check low−voltage transformer leads R (red) and C

(brown). Be sure they are wired to correct locations.

2. Check output voltage of transformer secondary side R

(red) and C (brown). Be sure transformer output is

between 18Vac and 30Vac. If transformer output is

incorrect and transformer is receiving correct input

voltage (208V or 230V), then transformer needs to be

replaced with recommended transformer. If no problem

exists with transformer secondary, proceed to items 3

and 4.

3. Check low−voltage fuse shown in Figure 1. If fuse is

blown, replace it with an identical 5−amp fuse. The

transformer cannot supply power to board with fuse

blown or loose. If fuse blows when unit has power

applied to it, the system most likely has one of the

following problems:

a. Check all 24−V wiring for an electrical short.

b. The maximum load on transformer is 40 VA. If load

on transformer is excessive, the low−voltage 5−amp

fuse will blow to protect transformer. If load exceeds

VA rating of transformer, a larger VA rated

transformer needs to be installed. Check

sequencers/relays for excessive current draw.

c. Check wiring of heaters. If a heater is miswired,

fuse may blow. If a heater is miswired, correct

miswiring by comparing it to heater wiring label.

4. Check connections on primary side of transformer. If

they are not connected properly, the transformer

secondary cannot supply the 24−V signal to energize

fan relay. If transformer is receiving correct primary

voltage but is not putting out correct secondary voltage,

transformer needs to be replaced.

B. If Electric Heat Stages Will Not Turn On But Fan Will

Turn On:

IF THERE IS NO HIGH VOLTAGE TO TRANSFORMER:

1. Check plug connection between heaters and board.

This supplies power to transformer and fan. Be sure

plug is connected properly.

2. Check sequencer/relay No. 1 and plug wiring. Yellow

wire should be connected to Pin No. 9 of plug and to

limit switch. Black wire should be connected to Pin No.

7 of plug and to sequencer/relay No. 1.

3. Check incoming high−voltage power leads. If these are

not receiving power, system cannot function.

SERVICE AND MAINTENANCE FAN COILS

4496 08 8001 00

Specifications subject to change without notice.

IF TRANSFORMER HAS VOLTAGE APPLIED TO IT:

1. Check low−voltage transformer leads R (red) and C

(brown). Make sure they are wired to correct location.

The unit will not function without proper connections.

2. Check output voltage of transformer secondary side R

(red) and C (brown). If transformer output is low (less

than 18Vac), refer to items 3 and 4 of previous “If

Transformer Has High Voltage Applied To It” section.

IF TRACES ARE OVERHEATED ON BACK OF PCB:

Usually whenever a trace is blown on PCB, it means either

there has been a high−voltage short or high voltage has been

applied to low−voltage circuit. This can be prevented by

making sure PCB is wired correctly before PCB has power

applied to it.

C. If Transformer Fuse Keeps Blowing:

When low−voltage fuse blows, it means transformer would

have blown if fuse had not been in circuit to protect it. The

fuse usually blows when there is a high current draw on

transformer, high voltage applied to low−voltage circuit, or a

direct secondary short. When there is a high current draw on

transformer, it is most likely because transformer has been

shorted or system is trying to draw more VA than transformer

rating allows. When fuse blows because of high voltage, the

system has mixed high−and low−voltage signals.

1. Check wiring of sequencers/relays as shown in

Figure 1. Be sure transformer is not shorting out

because thermostat wires are miswired.

2. Check wiring of relays as shown in Figure 1. Be sure

low−voltage and high−voltage wiring is correct.

3. Check VA draw on transformer. If VA draw is more than

VA rating of transformer, fuse will blow. If this is the

case, replace transformer with one that has a higher

VA rating and meets system specifications.

D. If Fan Runs Continuously:

1. If PCB has no low−voltage power, check blue and

black fan leads. These may be switched at

sequencer/relay.

2. If PCB has low−voltage power, check fan relay to see if

it is opening and closing. It may be stuck in the

normally closed position due to debris in relay.

E. Transformer Failure:

Check 208−V and 230−V transformer connections. They may

be miswired.

Figure 1 −Fan Coil Printed Circuit Board (contact FAST for part number)

CPC-E

94V-0

LR40061

HSCI

5 AMP

SPT

R10

R11

C1C2

JW1

FAN

RELAY

Representative drawing only. Please contact FAST for part number.

A03010

Figure 2 −Electric Heater Control Box

312753

T-O-D 60TX11

HH19ZA945

C9725

L145-55F

312753

T-O-D 60TX11

HH19ZA945

C9725

L145-55F

SPT

FAN

RELAY

5PULL TO OPEN

WARNING

ELECTRIC SHOCK

HAZARD

DISCONNECT

REMOTE POWER

SUPPLY BEFORE

OPENING PANEL.

322861-101 REV. A

A13032

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 5

Specifications subject to change without notice.

FEM4P, FEM4X, FEA4X, FXM4, WAHA, WAPM,

WAPT, WAPL, WAHM, WAHT, WAHL, WAXM,

WAXT, WAXL, REM4P, REM4X

MULTI−SPEED ECM FAN MOTOR

The multi−speed ECM motor used with this product contains

two parts: the control module and the motor winding section.

Do not assume the motor or module is defective if it will not

start. Go through the steps described below before replacing

control module or entire motor. The control module is

available as a replacement part.

A. It is normal for the motor to rock back and forth on startup.

Do not replace the motor if this is the only problem

identified.

B. If the motor is not running:

1. Check for proper high voltage and ground at the L,G,

and N connections at the motor. Correct any voltage

issue before proceeding to the next step.

2. The motor is communicated through 24−Vac signals to

the 1,2,3,4,5 and C (common) terminals. Not all taps

are programmed, if low voltage is applied to an

non−programmed terminal, the motor will not operate,

which is normal. Verify the part number of the motor

matches the correct replacement motor part number for

the unit model number.

3. Initiate a demand from the thermostat and check the

voltage between C (common) and terminal 1−5. If

voltage is present and the motor isn’t operating, then

the motor/control module is failed.

C. Prior to installing the replacement control module, the

motor section condition needs to be verified.

1. Check to see if the blower wheel spins freely.

2. To check for short to ground, use an ohmmeter to

measure the resistance from any one of the motor

connector pins to the aluminum end plate of the motor.

This resistance should be greater than 100,000 ohms.

3. Check the motor phase−to−phase resistance between

each of the leads in the three−pin motor connector. The

lead−to−lead resistance across any two leads should

be less than 20 ohms. Each lead−to−lead resistance

should be the same within −/+ 10 percent.

4. If any motor fails any of the three tests, do not install a

new control module. The new control can fail if placed

on a defective motor.

The prior fan coil models with multi−speed ECM blower

motors used a printed circuit board, similar to the PSC

models. The current fan coils do not use the printed circuit

board and rely on the motor control programming to provide

the off−delay timing.

Another design aspect of the control board was to provide a

resistor in the “G” circuit in case a power stealing thermostat

was used. This resistor is no part of the wiring harness, as

shown on wiring diagram. The resistor is a 2−watt, 1500−ohm

resistor.

If the resistor has failed open, a likely cause is due to the

power stealing thermostat. Connecting C (common) may

resolve the issue. Having an open resistor should not affect

the operation of the motor.

Fan Speed Selection

The fan speed selection is done at the motor connector.

Units with or without electric heaters require a minimum CFM.

Refer to the unit wiring label to ensure that the fan speed

selected is not lower than the minimum fan speed indicated.

To change motor speeds disconnect the BLUE fan lead from

motor connector terminal No. 2 (factory default position) and

move to desired speed-tap; 1, 2, 3, or 5.

Speed-taps 1, 2, and 3 have a 90−second blower off time

delay pre-programmed into the motor. Speed-tap 4 is used

for electric heat only (with 0 second blower time delay) and

the WHITE wire should remain on tap 4. Speed-tap 5 is used

for high static applications, but has a 0−second blower time

delay pre-programmed into the motor. See Airflow

Performance tables for actual CFM. Also, see Figure 3 for

motor speed selection location.

NOTE: In low static applications, lower motor speed tap

should be used to reduce possibility of water being blown off

coil.

Tap 1 Low 90 sec off delay

Tap 2 Medium 90 sec off delay

Tap 3 High 90 sec off delay

Tap 4 Electric heat † 0 sec off delay

Tap 5 Max ‡ 0 sec off delay

† electric heat airflow is same CFM as Tap 3, except 0 sec off delay

‡ high static applications, see airflow tables for max airflow

Figure 3 −Motor Speed Selection

1 2 3 4 5

Speed Taps may be located on motor,

or on plug close to motor.

CLGN

1 2 3 4 5

TWO MOTOR STYLES

A11048

SERVICE AND MAINTENANCE FAN COILS

6496 08 8001 00

Specifications subject to change without notice.

Figure 4 −FVM4 motor/ECM 5.0 Motor

NAMEPLATE

LABEL

A13028

FVM4

Constant Air Flow

Unlike fan coils using induction motors where static pressure

affects airflow, these fan coils are constant airflow units. The

blower delivers requested airflow regardless of static

pressure. Consult fan coil Specification Sheet for static

pressure limits. The ECM 5.0 is pre−programmed and

contains airflow tables for all modes of operation. Blower

characteristics (requested airflow, torque, and speed) are

known from laboratory testing If any two characteristics are

known, the third is defined.

Requested airflow is known from Easy Select Board

configuration and thermostat signals. Torque is known

because it is directly related to stator current, which is

measured by motor control. Speed is measured by counting

back EMF pulses from stator windings. This information is

entered into an expression that calculates torque from speed

and airflow numbers. If calculation does not match stored

blower characteristics, torque is adjusted until agreement is

reached. This calculation and adjustment is performed every

0.8 seconds while motor is in operation. There is no direct

measure of static pressure, but unit does react to a change in

static to maintain constant airflow. A change in pressure will

result in a change in stator speed and torque. The motor will

begin to adjust on the next sampling, calculate new desired

speed and torque, and adjust as necessary.

INTEGRATED CONTROLS AND MOTOR ECM 5.0

An ECM 5.0 is fed high voltage AC power through the 5−pin

connector. (See Figure 4.) The AC power is then internally

rectified to DC by a diode module. After rectification, DC

signal is electronically communicated and fed in sequential

order to three stator windings. The frequency of these

commutation pulses determines motor speed. The rotor is

permanently magnetized.

An ECM 5.0 is powered with high voltage at all times. The

motor will not run with high voltage alone. Low voltage must

be applied to control plug to run motor.

ECM 5.0 Control Power

The ECM 5.0 control power is supplied from R circuit through

printed circuit runs to motor control Connector−Pin 8, through

motor control harness to motor. The C side of low−voltage

control power circuit is connected by printed circuit runs to

motor Connector −Pins 9, 10, and 11 then through motor

control harness to motor.

Low−Voltage Circuit Fusing and Reference

The low−voltage circuit is fused by a board−mounted 5−amp

automotive−type fuse placed in series with transformer SEC2

and R circuit. The C circuit of transformer is referenced to

chassis ground through a printed circuit run at SEC1

connected to metal standoff marked.

NOTE: The PCB must be mounted with two screws and

motor ground lead secured to blower housing or erratic motor

operation can result.

Transformer, Motor, and Electric Heater Power

Connection

Transformer high voltage supplied from electric heater

package or high voltage leads through 12−pin heater

connector plug2/recp2. The ECM 5.0 power connections are

made at the transformer primary terminals. The transformer

secondary connections are made at SEC1 and SEC2

connectors.

PCB LAYOUT AND DESCRIPTION

NOTE: Layout of actual PCB is depicted in Figure 5.

The Easy Select Board is the interface between the ECM

motor and other system components. The board offers

choices of electric heater size, outdoor unit size and type,

comfort or efficiency settings, on and off delay profiles, and

continuous fan speed. The installer should select the correct

size of components that are being installed in each

installation. If no selections are made, the factory default

settings are for the largest heater, largest outdoor unit, AC

system type, nominal airflow adjust, and 0/90 time delay.

NOTE: Outdoor unit model should have an AHRI rating with

the variable speed fan coil. Some outdoor unit models will not

work properly with this fan coil.

Power for system is supplied from a 230−Vac, 60−Hz line.

Class 2 voltage (24 Vac nom.), used for thermostat

connections, is derived from transformer located in close

proximity to PCB. The 24−Vac secondary circuit includes

5−amp automotive−type fuse in SEC2 circuit.

Connection to heater panel is made through 12−pin

connector PL−1. Connections to thermostat are made at

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 7

Specifications subject to change without notice.

screw terminals. Twenty−one pin terminals comprise field

select taps for motor.

Fuse Data: 5−amp automotive−type ATC/ATO (tan) at 32Vac,

200 percent current opening time of five seconds maximum.

Electrical Connections

Twenty−one 0.110−in pin terminals are used to provide

programming selections for operating modes of ECM 5.0. The

6 selection modes are listed below. For additional information,

refer to Easy Select Configuration Taps section.

AUX Heat Range—(Violet Wire)

AC/HP Size—(Blue Wire) Type—(Orange Wire)

AC/HP CFM Adjust—(Black Wire)

AC/HP Time Delay—(Grey Wire)

Continuous Fan—(Yellow Wire)

SEQUENCE OF OPERATION

A. Continuous Fan Mode

The thermostat closes circuit R to G. The unit delivers the

airflow selected for fan only operation.

B. Cooling Mode—Single Speed or Two−Speed High

Thermostat closes circuits R to G, R to Y/Y2 and R to O (heat

pump only). A circuit R to Y1 is required for two−speed high

operation. Airflow delivered the airflow selected by AC/HP

SIZE selection and CFM ADJUST selection.

C. Cooling Mode—Two−Speed Low

Thermostat closes R to G and R to Y1 and R to O (heat pump

only). Unit delivers two−speed low airflow for AC/HP SIZE

and CFM ADJUST selected.

D. Cooling + Dehumidify Mode

J1 jumper must be pulled from Easy Select Board. Control

closes R to G, R to Y/Y2, and R to O (heat pump only) and

open R to DH. Dehumidification is active when 24Vac is

removed from DH terminal. Unit delivers 20 percent less

airflow.

E. Super Dehumidify Mode

This mode is only activated when the control closes R to

Y/Y2, R to O (heat pump only) and opens R to DH and R to

G. This signals the fan coil to run at minimum airflow for

maximum humidity removal. The control will cycle the

equipment 10 minutes on and 10 minutes off until satisfied.

Table 1 – Motor and Modules

Model Size Motor Type Current Blower Motor

P/N

Required Control Module

Replacement Kit Number

FVM4X2400 (Series B) ECM 5.0 1185246 1185326

FVM4X3600 (Series B) ECM 5.0 1185247 1185327

FVM4X4800 (Series B) ECM 5.0 1185248 1185328

FVM4X6000 (Series B) ECM 5.0 1185249 1185329

Figure 5 −Easy Select Board 1185358

YYWWX

AUX/HEAT KW/CFM

AC/HP SIZE

AC/HP CFM ADJUST

ON/OFF DELAY

CONTINUOUS FAN

HEATER/MOTOR

AUX1 HUM1

AUX2

24VAC

HUM2

LO MED HI YEL

SYSTEM TYPE

SEC1

EASY SELECT

SEC2

5 AMP.

MAX.

D5D2

HK61EA006

STI

YEL

PL1

GRY

WHT

BLK

ORN

BLU

VIO

0-30

1075

0-20

875

0-10

725

0-5

625

036 030 024 018

AC HP-COMFORT HP-EFF

NOM LO HI

ENH

Y/Y

SERVICE AND MAINTENANCE FAN COILS

8496 08 8001 00

Specifications subject to change without notice.

Figure 6 −Easy Select Board Schematic

AUX1

SYSTEM DIAGRAM

HEATER/MOTOR

SEC1 SEC2

5 AMP J1

Y/Y

HUM1

AUX2

HUM2

DIODE

LOGIC

AUX HEAT

KW/CFM AC/HP

SIZE SYSTEM

TYPE AC/HP CFM

ADJUST ON/OFF

DELAY CONTINUOUS

FAN

GRY

A96431

Table 2 – FVM4X Connections and Connectors

Type Connection Type Connector Pin No. Description

Heater Connection 12-Pin

Pin 1 Common to screw terminal G

Pin 2 Common to screw terminal Y/Y2 through diode D3

Pin 3 Common through Y1 through diode D2

Pin 4 Common to W2 screw terminal

Pin 5 Common to W2 screw terminal

Pin 6 Common to W1 screw terminal

Pin 7 Common to W1 screw terminal

Pin 8 R 24Vac

Pin 9 Common to transformer C

Pin 10 Common to transformer C

Pin 11 Common to transformer C

Pin 12 Common to DH screw terminal

Table 3 – Typical Operating Modes

Operating Mode Terminals Energized

Heat Pump Only Heating R, Y/Y2, G, DH

Heat Pump Only Heating + Super Comfort Heat Mode R, Y/Y2, DH

Heat Pump Heating + Auxiliary Heat (non-staged) R, Y/Y2, G, DH, W2

Cooling R, Y/Y2, G, DH, O

Cooling + Dehumidification R, Y/Y2, G, O

Cooling + Superdehumidification R, Y/Y2, O

F. Heat Pump Heating Mode — Single Speed or

Two−Speed High

Thermostat closes R to Y/Y2 and R to G. A circuit R to Y1 is

required for two−speed high operation. The unit delivers

airflow selected by AC/HP SIZE selection and CFM ADJUST

selection. Selected delay profile is active in this mode.

G. Heat Pump Heating Mode — 2−Speed Low

Thermostat closes R to G and R to Y1. Unit delivers

two−speed low airflow for AC/HP SIZE and CFM ADJUST

selected. Selected delay profile is active in this mode.

H. Non−Staged Auxiliary with Heat Pump Heating Mode

Thermostat should already have closed R to G, R to Y2 for

heat pump heating operation. With J2 jumper in place,

energizing either W1 or W2 will produce the W2 airflow. This

is the greater of heat pump heating and auxiliary heat airflow

plus an additional 15 percent. The elected delay profile is not

active in this mode.

I. Staged Auxiliary Heat with Heat Pump Heating Mode

The auxiliary heat can be staged by removing the J2 jumper

that ties W1 and W2 terminals together. Staging can be done

by using outdoor thermostats or by using the heat staging

option where the indoor control can be configured for

three−stage electric heat. The unit will automatically adjust

airflow when the different stages of heat are energized. The

airflow delivered will depend on the heat pump size selected

and electric heat size selected. The greater of the two

airflows will be delivered. The selected delay profile is not

active in this mode.

J. Electric Heat without Heat Pump

Thermostat closes R to W and thermostat should be set up to

energize G with W. This is due to the Super Comfort Heat

programming in the motor. Energizing W without G will result

in 25% lower airflow delivery. The selected delay profile is not

active in this mode.

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 9

Specifications subject to change without notice.

EASY SELECT CONFIGURATION TAPS

The Easy Select taps are used by installer to configure

system. The ECM 5.0 uses selected taps to modify its

operation to a pre−programmed table of airflows. Airflows are

based on system size and mode of operation and those

airflows are modified in response to other inputs such as the

need for de−humidification. (See Figure 5.)

The FVM4 Fan Coils must be configured to operate properly

with system components with which it is installed. To

successfully configure a basic system (see information

printed on circuit board located next to select pins), move the

six select wires to pins which match components used, along

with homeowner preferences.

A. Auxiliary Heat Range

The installer must select the auxiliary heat airflow approved

for application with kW size heater installed. Each select pin

is marked with a range of heaters for which airflow (also

marked) is approved. For increased comfort select the

narrowest kW range matching the heater size, for example,

0−10 for a 10−kW heater. This airflow must be greater than

the minimum CFM for electric heater application with the size

system installed for safe and continuous operation. Note that

airflow marked is the airflow which will be supplied in

emergency heat mode and heating mode on air conditioners

when electric heat is primary heating source. To ensure safe

heater operation in heat−pump heating mode, when electric

heaters are energized, the ECM 5.0 will run the higher of heat

pump airflow and electric heater airflow. The factory default

selection is largest heater range approved. (See Figure 5.)

B. AC/HP Size

The factory default setting for air conditioner or heat pump

size is largest unit meant for application with model of fan coil

purchased. The installer needs to select air conditioner or

heat pump size to ensure that airflow delivered falls within

proper range for size of unit installed in all operational modes.

(See Figure 5.)

Unpack unit and move to final location. Remove carton taking

care not to damage unit. Inspect equipment for damage prior

to installation. File claim with shipping company if shipment is

damaged or incomplete.

Locate unit rating plate which contains proper installation

information. Check rating plate to be sure unit matches job

specifications.

C. System Type

The type of system must be selected.

1. AC—air conditioner (approx. 350 CFM/ton)

2. HP−COMFORT—provides lower airflow than air

conditioner selection (approximately 315 CFM/ton) in

heating mode. In cooling mode supplies 350 CFM/ton.

3. HP−EFF—provides same airflow for heat pump heating

and cooling modes (approximately 350 CFM/ton).

The factory setting is AC. (See Figure 5.)

D. AC/HP CFM Adjust

Select low, nominal, or high airflow. The factory selection is

NOM. The adjust selections HI/LO will regulate airflow

supplied for cooling and heat pump heating modes only, +15

percent and −10 percent respectively. The adjust selection

options are provided to adjust airflow supplied to meet

individual installation needs for such things as noise, comfort,

and humidity removal. (See Figure 5.)

E. ON/OFF Delay

NOTE: ON/OFF Delay is active only in cooling and heat

pump only heating modes. In auxiliary heat mode or

emergency heat mode, the ON delay is 0 seconds and the

OFF delay is fixed and cannot be overridden.

Select desired time delay profile. Four motor−operation delay

profiles are provided to customize and enhance system

operation. (See Figure 5.) The selection options are:

1. The standard 90−seconds off delay (factory setting

0/90).

2. No delay option used for servicing unit or when a

thermostat is utilized to perform delay functions (0/0).

3. A 30−seconds on/90−seconds off delay profile used

when it is desirable to allow system coils time to heat

up/cool down prior to airflow. This profile will minimize

cold blow in heat pump operation and could enhance

system efficiency (30/90).

4. ENH, enhanced selection provides a 30−seconds

on/150−seconds at 70 percent airflow and no off delay.

F. Continuous Fan

Select desired continuous−fan profile LO, MED, or HI. Airflow

are provided to customize and enhance the continuous fan

functions. (See Figure 5.) The possible selections are:

1. LO—provides 50 percent of Y/Y2 Cool airflow.

2. MED—provides 65 percent of Y/Y2 Cool airflow (71

percent on 5 ton model).

3. HI—provides 100 percent of Y/Y2 Cool airflow.

The factory setting is LO.

NOTE: If applied to two−speed unit, do not select continuous

fan as HI since low speed cooling will also run at HIGH airflow

and insufficient dehumidification may result.

G. Easy Select Board Jumpers

J1 −This jumper must be pulled to activate dehumidification

mode. The jumper connects R to DH. With the jumper in, the

DH terminal is always energized. With the jumper pulled, the

DH terminal is de−energized. A thermostat capable of a

DEHUM feature must be used to supply the 24−V signal

when there is no call for dehumidification, and turn off the

24−V when there is a call for dehumidfication.

J2 −This jumper activates heat staging. The jumper connects

the W1 and W2 terminals together. If either is energized, W2

airflow is delivered. With the jumper pulled, there are

separate airflows for W1 and W2.

H. Airflow Delivery

These units deliver airflow depending on the system size

selections and operating mode. The thermostat energizes a

combination of terminals on the Easy Select Board which tells

the motor what CFM to deliver. The following are typical

operating modes and the terminals that should be energized

on the Easy Select Board.

NOTE: The DH terminal on the Easy Select Board is for

dehumidification. It is de−energized on a call for

dehumidification.

I. Variable Speed Motor Logic Sequence:

The ECM motors in these fan coils are programmed to deliver

a variety of airflows. The motor goes through:

COOLING

The nominal cooling airflow for these fan coils is 350 CFM per

ton. Selecting the HI adjust tap increases the airflow to 400

CFM per ton. The LO tap decreases airflow to 315 CFM per

ton. The low adjustment is only active during normal cooling

mode. Removing the signal from the DH terminal reduces the

airflow to 80 percent of cooling airflow. Removing the G signal

SERVICE AND MAINTENANCE FAN COILS

10 496 08 8001 00

Specifications subject to change without notice.

which initiates Superdehumidification and reduces the airflow

to 50 percent of cooling.

HEATING

The base heat pump only heating airflow is determined by the

SYSTEM TYPE selection on the Easy Select Board. If

HP−EFFICIENCY is selected, the airflow is the same as

Cooling. IF HP−COMFORT is selected, the airflow is 315

CFM per ton. The airflow will adjust up if necessary when

auxiliary heating is required. When both the Y/Y2 and W1 or

W2 terminals are energized, the motor will run the higher of

the heat pump or electric heat airflows. Super Comfort Heat

mode is initiated when the indoor control removes the G

signal from the board. This slows the motor to 75 percent of

heat pump airflow. If the CFM adjust is set to LO, it will deliver

67.5 percent of heat pump airflow during Super Comfort Heat

mode.

TROUBLESHOOTING

A. Troubleshooting Easy Select Board (FVM4)

If Traces Are Overheated on Back of PCB:

Usually whenever there is a trace broken on PCB, it means

either there has been a high−voltage short or high voltage

has been applied to low−voltage circuit. This can be

prevented by making sure PCB is wired correctly before fan

coil has power applied to it.

If PCB Fuse Keeps Blowing:

When low−voltage fuse blows, it means transformer would

have blown if fuse had not been in circuit to protect it. The

fuse usually blows when there is a high current drawn on

transformer, high voltage applied to low−voltage circuit, or a

direct secondary short. When there is a high current drawn on

transformer, it is most likely because transformer has been

shorted or system is trying to draw more Vac than transformer

rating allows. When fuse blows because of high voltage, the

system has mixed high and low−voltage signals.

1. Check transformer and thermostat wiring. (See

Figure 5.) Be sure transformer is not shorting out

because thermostat wires are miswired.

2. Check wiring of relays. (See Figure 5.) Be sure

low−voltage and high−voltage wiring are connected to

proper sequencers.

3. Check VA draw on transformer. If VA draw is more than

VA rating of transformer, fuse will blow. If this is the

case, replace transformer with one that has a higher

VA rating.

B. Troubleshooting Common Problems

Airflow Too Low:

Y1 instead of Y/Y2 on single−speed air conditioner or heat

pump application. Y1 input is only for two−speed applications.

Using this terminal will deliver about 60 percent of full cooling

airflow.

Wrong Easy Select Board selection. Selecting an outdoor unit

or electric heater smaller than actually installed will result in

low airflow for the application.

G not energized with call for cooling or heating. This triggers

Super Comfort Heat or SuperDehumidify mode which delivers

50 percent of cooling airflow.

J1 jumper pulled with no dehumidistat installed. The J1

jumper ties the DH terminal to R and is installed at the factory.

When pulled, a dehumidistat supplies a 24−V signal to DH

when there is no call for dehumidification (reverse logic).

When there is no signal on DH, the motor reduces airflow to

80 percent for better dehumidification.

Airflow Too High:

Wrong Easy Select Board selection. Fan coil is factory set for

the largest outdoor unit and largest electric heater. Select

sizes that are actually installed.

Continuous fan set too high for two−speed applications. Set

to MED or LO.

Motor Will Not Stop:

The off delay on any W call is one minute and cannot be

overridden.

Some power−stealing thermostats could bleed enough

voltage to cause motor to run slowly when there is no heating

or cooling call. Disconnect thermostat wires and wait two

minutes to see if motor stops. If it stops, replace thermostat,

or install resistor per thermostat installation instructions.

Motor Will Not Start:

See following section, “Troubleshooting ECM 5.0 Motor and

Controls

C. Troubleshooting ECM 5.0 Motor and Controls

ELECTRICAL OPERATIONS HAZARD

Failure to follow this caution may result in equipment

damage or improper operation.

High voltage is always present at motor. Disconnect

power to unit before removing or replacing connectors

or servicing motor. Wait at least five minutes after

disconnecting power before opening motor.

CAUTION

The ECM/ICM motor used with this product contains two

parts: the control module and the motor winding section. Do

not assume the motor or module is defective if it will not start.

Go through the steps described below before replacing

control module, Easy Select Board or entire motor. The

control module is available as a replacement part.

D. If Motor Turns Slowly:

1. It is normal operation to run noticeably slower if G

terminal is not energized in cooling or heat pump

heating modes.

2. Attach blower access panel. Motor may appear to run

slowly if access panel is removed.

E. If Motor Does Not Run:

Turn power off, wait five minutes and check the following:

1. With power turned off, check 5−amp fuse on Easy

Select Board.

2. Check all plugs and receptacles for any deformation or

corrosion that could cause bad connections. Be sure

plugs are fully seated.

ELECTRICAL OPERATION HAZARD

Failure to follow this caution may result in equipment

damage or improper operation.

DO NOT remove or apply 5−pin plug on motor with

power on. Arcing could occur, which can damage

control module

CAUTION

Turn power back on and check the following:

3. Check for 24Vac on SEC1 and SEC2. If no voltage is

present, check transformer.

4. Verify that approximately 230Vac is present at motor.

5. Verify low voltage control signals to motor according to

procedure below.

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 11

Specifications subject to change without notice.

Use following procedure to check low voltage signals:

The ECM motor in these fan coils receive low voltage signals

from the Easy Select Board through the wiring harness

assembly. The combination of pins energized at the motor

determines the speed the motor will run. The procedure

below isolates the fan coil from all external devices such as a

thermostat, condensing unit, humidifier or electronic air

cleaner. There is also a specific troubleshooting example to

demonstrate the process. Table 7 provides information

needed to verify that the correct voltages are present at the

motor and the Easy Select Board.

THERMOSTAT:

1. Remove all thermostat and accessory wires from Easy

Select Board.

2. On Easy Select Board, jumper screw terminals (1 at a

time): R−G, R−Y/Y2, R−Y1, R−W1, R−W2. If motor

runs in all cases, check thermostat outputs. Thermostat

wires may be broken, or thermostat may be miswired,

configured incorrectly, or defective. If the motor does

not run, or runs in some cases, but not others, continue

this procedure to check wiring harness and circuit

board.

WIRING HARNESS:

1. Remove 16−pin plug from motor.

2. Check for appropriate voltages on 16−pin connector

with screw terminals jumpered. (See Table 2.)

3. If signals check correctly, and motor does not run,

inspect wiring harness for loose pins or damaged

plastic that could cause poor connections.

4. If connections are good, either control module or motor

is defective.

5. If proper signals are not present, check circuit board

using procedure below:

12−PIN PLUG (PL−1) ON Easy Select Board:

1. Completely disconnect wire harness from Easy Select

Board.

2. Jumper the screw terminals one at a time; R−G,

R−Y/Y2, R−Y1, R−W1, R−W2 and check for

appropriate voltages on the Easy Select Board pins. If

proper signals are not present, replace Easy Select

Board. If proper signals are present at the pins and not

at 16−pin connector to the motor, the wiring harness is

defective.

TROUBLESHOOTING EXAMPLE:

Motor is not running on a call for heat pump heating after

jumpering the Easy Select Board screw terminals as

described in Thermostat section above.

With all thermostat wires removed from Easy Select Board,

place a jumper wire between R and Y/Y2 low−voltage screw

terminals on the Easy Select Board.

1. Check Table 4 for pin number on 16−pin connector

associated with the Y/Y2 signal. The correct pin is No.

14. The far right column of Table 4 shows that (−)

12Vdc should be present between Pin No. 14 and Pin

No. 1 (common) on the 16−pin connector.

2. Set meter to read DC voltage. Place meter leads

between Pins No. 1 (common) and No. 14 and check

for (−) 12Vdc. If signal is present, the problem is in the

module or motor. If signal is not present, the problem is

either in wiring harness or Easy Select Board.

These steps can be repeated for other modes of operation.

To check Easy Select Board:

1. Leave jumper wire in place between R and Y/Y2.

2. Check Table 4 under Volt Meter on Easy Select Board

Plugcolumn and row for Pin No. 14 on motor plug to

see pin number on Easy Select Board that should have

voltage. The correct pin is No. 2. The column on far

right will show voltage that should be present between

Pin No. 2 and Pin No. 9 (common).

3. Place meter leads between Pins No. 2 and No. 9 on

Easy Select Board and check for (−) 12Vdc.

4. If voltage is present, the wiring harness is bad. If not,

the Easy Select Board is bad.

Verify Motor Winding Section:

Before proceeding with module replacement, check the

following to ensure motor winding section is functional. With

control module removed and unplugged from winding section:

1. The resistance between any two motor leads should be

similar.

2. The resistance between any motor lead and the

unpainted motor end plate should be greater than

100,000 ohms.

If motor winding fails one of these tests, it is defective and

must be replaced.

F. Dehumidify Mode

NOTE: Humidistat must open on humidity rise.

Latent capacities for systems using the FVM4 fan coils are

better than average systems. If increased latent capacity is

an application requirement, the field wiring terminal block

provides connection terminals for use of a standard

humidistat. The FVM4 fan coils will detect the humidistat

contacts opening on increasing humidity and reduce its

airflow to approximately 80 percent of nominal cooling mode

airflow. This reduction will increase the system latent capacity

until the humidity falls to a level which causes the humidistat

to close its contacts. When the contacts close, airflow will

return to 100 percent of the selected cooling airflow. To

activate this mode, remove jumper J1 and wire in a standard

humidistat. Carefully consult product airflow data for cooling

and dehumidification modes.

Table 4 – FVM4 Motor Control Test Values (With 16−pin connector at motor unplugged)

Terminals

Jumpered

Volt Meter on 16-pin Harness

Plug

Volt Meter on 12-pin

Easy Select Board Plug Voltage

+ - + -

R to W1 Pin 2 Pin 1 Pin 7 Pin 9 24Vac

R to W2 Pin 13 Pin 1 Pin 4 Pin 9 24Vac

R to Y1 Pin 6 Pin 1 Pin 3 Pin 9 (-)12Vdc

R to Y/Y2 Pin 14 Pin 1 Pin 2 Pin 9 (-)12Vdc

R to G (LO) Pin 15 Pin 1 Pin 3 Pin 9 0Vac

R to G (MED) Pin 6 Pin 1 Pin 3 Pin 9 (-)12Vdc

R to G (HI) Pin 14 Pin 1 Pin 2 Pin 9 (-)12Vdc

SERVICE AND MAINTENANCE FAN COILS

12 496 08 8001 00

Specifications subject to change without notice.

Figure 7 −Humidistat Wiring for De−Humidify Mode

EASY SELECT

BOARD TERMINAL

BLOCK

HUMIDISTAT

REMOVE

JUMPER

A95316

FCM4

Model FCM4 fan coil is designed to be installed with the

Observertcommunicating wall control. The FCM4 fan coil

will provide airflow at a rate commanded by the Observer wall

control. The nominal airflow/ton rate is 350 CFM/ton. The

Observer wall control will modify the commanded airflow

under certain operating modes. Refer to the Observer wall

control literature for further system control details. This fan

coil will not respond to commands from a common thermostat

except under certain emergency situations explained in this

document.

ELECTRONICALLY COMPUTED MOTOR ECM 3.0

An ECM 3.0 is fed high voltage AC power through the 5−pin

connector. The AC power is then internally rectified to DC by

a diode module. After rectification, DC signal is electronically

communicated and fed in sequential order to 3 stator

windings. The frequency of these communication pulses

determines motor speed. The rotor is permanently

magnetized.

ECM 3.0 CONTROL POWER

The ECM 3.0 control power is supplied from R circuit through

printed circuit runs to motor control connector Plug 1, Pin 1,

through motor control harness to motor. The C side of

low−voltage control power circuit is connected by printed

circuit runs to motor connector Plug 1, Pin 2 then through

motor control harness to motor. A digital signal is sent from

Plug 1, Pins 3 and 4 to communicate with the motor including

all airflow requirements.

LOW−VOLTAGE CIRCUIT FUSING AND REFERENCE

The low−voltage circuit is fused by a board−mounted 5−amp

automotive type fuse placed in series with transformer SEC2

and R circuit. The C circuit of transformer is referenced to

chassis ground through a printed circuit run at SEC1

connected to metal standoff.

NOTE: The PCB must be mounted with two screws and

motor ground lead secured to blower housing or erratic motor

operation can result.

TRANSFORMER, MOTOR, AND ELECTRIC HEATER

POWER CONNECTION

Transformer high voltage supplied from electric heater

package or high voltage leads through 12−pin heater

connector plug/recp2. The ECM 3.0 power connections are

made at the transformer primary terminals. The transformer

secondary connections are made at SEC1 and SEC2

connectors.

TROUBLESHOOTING

NOTE: Always check high and low voltage supply to the fan

coil components. Check the integrity of the plug receptacle

connections and fan coil wiring harness prior to assuming a

component failure.

A. LED Description:

LEDs built into fan coil control provide installer or service

person information concerning operation and/or fault

condition of the fan coil control and ECM motor. This

information is also available at the Observer wall control in

text with basic troubleshooting instructions. Careful use of

information displayed will reduce the need for extensive

manual troubleshooting.

The amber LED located at bottom center of control adjacent

to motor harness plug is Motor Status LED, and it is labeled

MOTOR. A second amber LED, located in upper right center

of control adjacent to System Communications connector

(DX+, DX−, C, R), is the System Status LED, and it is labeled

STATUS. The green LED labeled COMM is also located

adjacent to System Communications connector, below

STATUS LED, and is used as an indicator of system

communications status. Status Codes will be displayed on

the STATUS LED using the following protocol:

1. The number of short flashes indicates first digit of code.

2. The number of long flashes indicates second digit of

code.

3. A short flash is 0.25 seconds on. A long flash is one

second on.

4. The time between flashes is 0.25 seconds.

5. The time between last short flash and first long flash is

1 second.

6. The LED will be off for 2.5 seconds before repeating

code.

B. Fan Coil Control Start−Up and System

Communications Troubleshooting:

On power up, green COMM LED will be turned off until

successful system communications are established (this

should happen within 10 seconds). Once communications

with Observer wall control are successful, COMM LED will be

lit and held on. At the same time, amber STATUS LED will be

lit and held continuously on until a request for operating mode

is received. The STATUS LED will be on any time fan coil is in

idle mode.

If, at any time, communications are not successful for a

period exceeding two minutes, fan coil control will only allow

emergency heating or cooling operation using a common

thermostat, a non−communicating outdoor unit and the R, C,

Y, O, W outdoor unit terminal strip connections and will

display Status Code 16, System Communication Fault, on

amber STATUS LED. No further fan coil troubleshooting

information will be available at Observer wall control until

communications are re−established.

If COMM LED does not light within proper time period and

status code is not displayed:

1. Check system transformer high and low voltage to be

sure the system is powered.

2. Check fuse on fan coil control to be sure it is not blown.

If fuse is open, check system wiring before replacing it

to be sure a short does not cause a failure of

replacement fuse.

If COMM LED does not light within proper time period and

status code is displayed:

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 13

Specifications subject to change without notice.

Check system wiring to be sure Observer wall control is

powered and connections are made DX+ to DX+, DX−to

DX−, etc. and wiring is not shorted. Mis−wiring or shorting of

the DX+, DX−, C, R communications wiring will not allow

successful communications.

NOTE: Shorting or mis−wiring low voltage system wiring will

not cause damage to fan coil control or Observer wall control

but may cause low voltage fuse to open.

C. ECM Motor Troubleshooting

The ECM motor used in this product consists of two parts: the

control module and the motor winding section. Do not

assume motor or module is defective if it will not start. Use the

designed−in LED information aids and follow troubleshooting

steps described below before replacing motor control module

or entire motor. Motor control module is available as a

replacement part.

Figure 8 −FCM4 ECM 3.0 Motor

A12231

VERIFY MOTOR WINDING SECTION:

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal

injury or death or possible equipment damage.

After disconnecting power from the ECM motor, wait at

least five minutes before removing the control section.

Internal capacitors require time to discharge. Minor

injury from electrical shock may result from early contact

with live metal parts.

!WARNING

Before proceeding to replace a motor control module:

1. Check motor winding section to be sure it is functional.

2. Remove motor control module section and unplug

winding plug. Motor shaft should turn freely, resistance

between any two motor leads should be similar and

resistance between any motor lead and unpainted

motor end should exceed 100,000 ohms.

3. Failing any of these tests, entire ECM motor must be

replaced.

4. Passing all of the tests, motor control module alone

can be replaced.

MOTOR TURNS SLOWLY:

1. Low static pressure loading of blower while access

panel is removed will cause blower to run slowly.

Particularly at low airflow requests. This is normal, do

not assume a fault exists.

2. Recheck airflow using Observer wall control service

screens with access panel in place.

NOTE: Blower motor faults will not cause a lockout of blower

operation. Fan coil control will attempt to run the blower motor

as long as the Observer wall control maintains a demand for

airflow. Fan coil control will not operate electric heaters while

a fault condition exists. The fan coil control communicates

with the motor at least once every five seconds, even when

the motor is idle. If, during operation, the fan coil control does

not communicate with the motor for more than 25 seconds,

the motor will shut itself down and wait for communications to

be reestablished.

D. Using Motor LED in Troubleshooting

The MOTOR LED is connected to the blower motor

communication line and works with the fan coil control

microprocessor and the STATUS LED to provide fan coil

operation and troubleshooting information. When the motor is

commanded to operate, the MOTOR LED will be turned on

and will flash each time instructions are sent to the motor.

When the motor is commanded to stop, the MOTOR LED will

be turned off.

If the MOTOR LED is lit, flashing and the motor is running or if

the MOTOR LED is off and the motor is stopped, operation is

normal and no motor fault exists.

If the MOTOR LED is lit, flashing and the motor does not run,

or if the MOTOR LED is off and the motor is running, check

the STATUS LED for the Status Code. Refer to the

troubleshooting instructions for the indicated Status Code in

Section E, Fan Coil Troubleshooting.

SERVICE AND MAINTENANCE FAN COILS

14 496 08 8001 00

Specifications subject to change without notice.

E. Fan Coil Troubleshooting

Fan coil faults indicated by flashing codes on the amber

system STATUS LED can be resolved using troubleshooting

information provided below. Codes are listed in order of their

priority, highest to lowest. Though multiple faults can exist at

any time, only the highest priority code will be displayed on

STATUS LED. Clearing the indicated fault when multiple

faults exist will cause the next highest priority Status Code to

be flashed. All existing faults, as well as a fault history, can be

viewed at Observer wall control.

STATUS CODE 45, CONTROL BOARD TEST FAULT:

Fan coil control has failed internal start−up tests and must be

replaced. No other service procedure will correct.

STATUS CODE 37, HEATER OUTPUT SENSED ON

WHEN NOT ENERGIZED:

Fan coil control is provided with circuitry to detect presence of

a 24−Vac signal on Electric Heater stage 1 and stage 2

outputs.

If fan coil control detects a 24−Vac signal on either heater

stage output and it is not supplying signal, Status Code 37

will be displayed on STATUS LED. Fan coil control will turn off

output and command blower motor to supply an airflow

determined to be safe for current operation mode with electric

heaters energized.

To find the fault:

1. Stop all system operations at Observer wall control and

check heater stage 24−Vac outputs.

2. Disconnect electric heater at plug/receptacle 2 and

check heater wiring for faults. See Status Code 36 for

more information.

STATUS CODE 44, MOTOR COMMUNICATION FAULT:

The MOTOR LED is connected to the blower motor

communication line and works with the fan coil control

microprocessor and STATUS LED to provide fan coil

operation and troubleshooting information.

When motor is commanded to operate, the MOTOR LED will

be turned on and will flash each time instructions are sent to

the motor.

When the motor is commanded to stop, the MOTOR LED will

be turned off. The MOTOR LED will not flash to indicate

communications when it is turned off.

Fan coil control is constantly communicating with the motor,

even when the motor and MOTOR LED are off. If motor does

not acknowledge receipt of communications, the control will

display Status Code 44 on STATUS LED and continue to try

to communicate with the motor. If motor acknowledges

communication, status code will be cleared.

If MOTOR LED is lit and flashing and motor does not run:

1. Check the STATUS LED. If STATUS LED is indicating a

Status 44 code, check the motor wiring harness for

proper connection to control and motor receptacles.

2. Check motor wiring harness to be sure all wiring

complies with wiring diagram description, makes a

complete circuit from connector to connector and is not

shorted.

3. Check 12−Vdc low−voltage supply to motor at Pins 1

(+) and 2 (−) of motor header connection to fan coil

control.

If all checks are normal, fan coil control is good and control

module on motor may need replacement. Check motor and

Motor Control Module following the instructions in Section C.

ECM Motor Troubleshooting.

Shorted or mis−wiring of the low voltage motor harness wiring

will not cause damage to fan coil control or to motor control

module.

If the MOTOR LED is off, STATUS LED is indicating a Status

Code 44 and motor is running:

Disconnect the motor harness at the fan coil control. If motor

continues to run, fan coil control is good and control module

on motor may need replacement

STATUS CODE 25, INVALID MOTOR / MODEL

SELECTION:

On initial start−up, fan coil control shall poll motor for its size

data and check fan coil size data stored in fan coil control

memory.

1. If motor size is incorrect for fan coil size or fan coil size

data is invalid, Status Code 25 will be displayed on

STATUS LED.

2. If model size data is missing (as is the case when a

replacement fan coil control is installed), Observer wall

control will prompt installer to enter correct model size

from a list of valid sizes.

3. If motor size is incorrect for model size, motor must be

replaced with proper size motor. Fan coil control will

not respond to operation requests until this fault

condition is resolved.

STATUS CODE 27, INVALID OUTDOOR UNIT SIZE:

On initial power−up, fan coil control will write into memory

outdoor unit size as provided by Observer wall control in a

fully communicating system.

1. If outdoor unit size is invalid, Status Code 27 will be

displayed on STATUS LED.

2. If model size data is missing (as is the case when a

replacement outdoor control is installed), Observer wall

control will prompt the installer to choose size from a

list of valid sizes for application with fan coil.

3. Check communications wiring to be sure Observer wall

control has established communications with outdoor

unit or select proper size from valid size list provided at

Observer wall control.

4. Check motor and motor control module following the

instructions in Section C. ECM Motor Troubleshooting.

STATUS CODE 26, INVALID HEATER SIZE:

On initial power−up, fan coil control will write into memory

electric heater size as read from heater if heater is provided

with Identifier Resistor (IDR). Heater size must be valid for

combination of indoor and outdoor components installed. Fan

coil control will read IDR value connected to Pins 5 and 8 of

heater harness connector. If no resistor is found, Observer

wall control will prompt installer to select heater size installed

from a list of valid heater sizes for fan coil and outdoor unit

size installed.

If heater ID resistor value read is invalid, Status Code 26 will

be displayed on STATUS LED.

If heater installed is equipped with a resistor connected to

Pins 5 and 8 of heater harness connector and Status Code

26 is displayed on STATUS LED:

1. Check wiring harness connections to be sure

connections are secure.

2. If symptoms persist, disconnect wiring harness at fan

coil control heater header and check for a resistance

value greater than 5000 ohms.

3. Check for proper wiring of resistor assembly.

4. Make sure heater size installed is an approved size for

outdoor unit and fan coil sizes installed.

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 15

Specifications subject to change without notice.

NOTE: Fan coil control will not operate electric heater until

this Status Code is resolved. If the heater size is set through

the Observer wall control, the heater will be operated as a

single stage heater. If staging is desired, the IDR value must

be read in by the fan coil control.

Table 5 – FCM4 self−identifying resistor values

Heater Size

Resistor Ohms

Nominal

No heater Open

911k

15 18k

20 24k

24 33k

30 39k

STATUS CODE 36, HEATER OUTPUT NOT SENSED

WHEN ENERGIZED:

Fan coil control is provided with circuitry to detect presence of

a 24−Vac signal on Electric Heater stage 1 and stage 2

outputs.

If fan coil control energizes either heater stage and does not

detect the 24−Vac signal on output, Status Code 36 will be

displayed on the STATUS LED Fan coil control will continue

to energize heater output(s) and adjust blower operation to a

safe airflow level for energized electric heat stage(s).

To find the fault, check for 24Vac on heater stage outputs.

Fan coil control or sensing circuit may be bad.

NOTE: It may be useful as an electric heater troubleshooting

procedure to disconnect the system communications to force

Status Code 16 enabling of emergency heat mode. It is

difficult to know which heater output is energized or not

energized in normal operation. When fan coil is operated in

emergency heat mode using electric heaters, both outputs

are energized and de−energized together. Terminal strip

inputs to control can then be connected R to W to turn on

both electric heat outputs. Heater output sensing circuits can

then be checked to resolve Status Code 36 or 37 problems.

STATUS CODE 41, BLOWER MOTOR FAULT:

If MOTOR LED is lit and flashing and motor does not run:

1. Check STATUS LED. If STATUS LED is indicating

Status Code 41, motor control has detected that the

motor will not come up to speed within 30 seconds of

being commanded to run or that the motor has been

slowed to below 250 rpm for more than 10 seconds

after coming up to speed. Motor wiring harness and fan

coil control are operating properly, do not replace.

2. Check to be sure that the blower wheel is not rubbing

the housing.

3. Check motor to be sure that the motor shaft is not

seized (motor control module must be removed and

electronics disconnected from windings to perform this

check properly).

4. Check motor windings section following instructions in

Section C. ECM Motor Troubleshooting.

If all these checks are normal, the motor control module may

need replacement.

STATUS CODE 16, SYSTEM COMMUNICATION FAULT:

If, at any time, system communications are not successful for

a period exceeding two minutes, the fan coil control will only

allow emergency heating or cooling operation using a

common thermostat, a non−communicating outdoor unit, and

the R, C, Y, O, W outdoor unit terminal strip connections and

will display Status Code 16 on the amber STATUS LED (see

section E, Emergency Heating and Cooling Modes). No

further fan coil troubleshooting information will be available at

the Observer wall control until communications are

reestablished.

Check system wiring to be sure the Observer wall control is

powered and connections are made DX+ to DX+, DX−to

DX−etc. and wiring is not shorted. Mis−wiring or shorting of

the DX+, DX−, C, R communications wiring will not allow

successful communications. Correcting wiring faults will clear

the code and reestablish communications.

Shorting or mis−wiring the low voltage system wiring will not

cause damage to fan coil control or to Observer wall control

but may cause the low voltage fuse to open.

STATUS CODE 46, BROWNOUT CONDITION:

If the secondary voltage of the transformer falls below 15Vac

for a period exceeding four seconds, Status Code 46 will be

displayed on STATUS LED.

If system includes a non−communicating outdoor air

conditioner or heat pump, the Observer wall control will

command the fan coil to turn off Y output controlling

compressor.

When secondary voltage rises above 17Vac for more than

four seconds, the brownout condition is cleared and normal

system operation will resume subject to any minimum

compressor off delay function which may be in effect.

Brownout does not affect blower or electric heater operation.

STATUS CODE 53, OUTDOOR AIR TEMPERATURE

SENSOR FAULT:

If an OAT sensor is found at power−up, input is constantly

checked to be within a valid temperature range. If sensor is

found to be open or shorted at any time after initial validation,

Status Code 53 will be displayed at amber STATUS LED.

Check for faults in wiring connecting sensor to OAT terminals.

Using an Ohmmeter, check resistance of thermistor for a

short or open condition.

If thermistor is shorted or open, replace it to return the system

to normal operation. If fault is in the wiring connections,

correcting the fault will clear the code and return the system

to normal operation.

NOTE: If fault condition is an open thermistor or a wiring

problem that appears to be an open thermistor and the power

to the fan coil control is cycled off, the fault code will be

cleared on the next power−up but the fault will remain and

system operation will not be as expected. This is because on

power−up, the fan coil control cannot discern the difference

between an open sensor or if a sensor is not installed.

F. Emergency Heating and Cooling Modes

Fan coil control can provide emergency heating or cooling

using a common heat/cool thermostat in the event that there

are no system communications, fault is in Observer wall

control and no replacement is immediately available.

To activate these modes, the thermostat and outdoor unit

must be wired as a common heating/cooling system to fan

coil control RYWC terminals. Fan coil control must be

powered and displaying Status Code 16, System

Communication Fault.

NOTE: These emergency modes do not provide the level of

comfort and efficiency expected by the consumer and should

only be activated when Observer wall control cannot be

replaced immediately.

SEQUENCE OF OPERATION

The FCM4 fan coil is designed for installation with Observer

communicating wall control. This fan coil will not respond to

commands provided by a common thermostat except under

SERVICE AND MAINTENANCE FAN COILS

16 496 08 8001 00

Specifications subject to change without notice.

certain emergency situations described in the Start Up and

Troubleshooting sub−section.

The Observer wall control uses temperature; humidity and

other data supplied from indoor and outdoor system

components to control heating or cooling system for optimum

comfort.

ADVANCED TROUBLESHOOTING:

Troubleshooting the FCM4 Fan Coil Circuit Board:

The circuit board Fan Coil part number 1184554

Primary test that should be performed:

Motor Line Voltage Check

1. Turn off power (240V).

2. Remove Plug 3 from ECM motor

3. Turn on power.

4. Check Plug 3, terminals 4 and 5, to ensure there are

240V.

5. Turn off power.

6. Reconnect Plug 3 to motor.

The following troubleshooting techniques will assist in

determining the correct component to replace when the Fan

Coil Board presents a Fault Code 44 or 41:

1. Disconnect power from the unit (240V).

2. Disconnect the DX+, DX−, C, R connector from the

board.

3. Disconnect Plug 1 from the board. (See Figure 10.)

4. Turn on power (240 volts).

5. After reestablishing power, you should receive Fault

Code 44, and the motor LED should be off.

6. Place a jumper across the R and G terminals on the

low voltage terminal block

7. Fault Code 44 should still be flashing.

8. The Motor LED should be flashing, indicating the board

is able to transmit a signal to the motor.

9. If Motor LED is not flashing, check to ensure that 24V

is present across R and C on the low voltage terminal

block and that there is a good connection with the R

and G jumper.

10. If 24V is present and the jumper/connections are

good,

11. Replace the board.

Check Board

12. If Fault Code 44 and the Motor LED are both flashing,

place a DC voltmeter across terminals PL1-1 Red (+)

to PL1-2 Green (-). (See Figure 10.)

13. Across terminal PL1−1 and PL1−2, a 12−Vdc should

be present. If 12Vdc is not present, replace circuit

board.

14. If Fault Code 44 is flashing and the Motor LED is

flashing, place a DC voltmeter across terminal PL1−3

(+) and PL1−2 (−).

15. Across terminal PL1−3 (+) and PL1−2 (−), the DC volt

meter should display 5Vdc. The voltage should be very

stable and should not fluctuate more than .02Vdc. If the

voltage fluctuates, get a different voltmeter before

proceeding to the following steps.

16. Reconnect Plug 1 to circuit board and connect DC

voltmeter across terminals PL1−3 Yellow (+) and

PL1−2 Green (−). Does the voltage appear to fluctuate

more than in step 15? Typical voltmeters will show a

fluctuation of .2Vdc to 1Vdc. The amount of fluctuation

is not important. You could see even more fluctuation

depending on the voltmeter used.

Figure 9 −FCM4 Circuit Board LED Locations

SECï1SECï2

FUSE 3AMP

HEATER

STATUS

COMM

MOTOR

HPT

OPN

COM

CLS

HUM Y

DX+DXïC R

A13031

Figure 10 −ECM/Plug Wiring Diagram

17. Check the blower motor serial output signal. The

blinking LED on the control board represents the serial

output signal. You can measure the signal with a DC

voltmeter by removing Plug 1 from the circuit board and

connecting the DC voltmeter across PL1−4 (+) and

PL1−2 (−). The voltage should be near 0Vdc but it will

fluctuate briefly several times per second. If you have

an analog voltmeter, the needle briefly will go high

several times per second. If you have a digital

voltmeter with a bar graph, it will show a large change

in magnitude on the bar graph several times per

second. If you have a plain, digital voltmeter, it will

show a brief fluctuation in voltage, and the magnitude

may vary depending on the voltmeter used.

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 17

Specifications subject to change without notice.

FMA4P, WAMA, FMA4X, WAXA

ELECTRICAL OPERATION HAZARD

Failure to follow this warning could result in personal

injury or death.

Before installation or servicing system, always turn off

main power to system. There may be more than one

disconnect switch. Turn off accessory heater power if

applicable. Lock out and tag switch with a suitable

warning label.

!WARNING

FAN MOTOR

FMA4P, WAMA

The FMA4P and WAMA motor is three−speed ECM direct

drive. High−speed lead is black, medium−speed lead is red,

low−speed lead is blue, and common lead is purple. Be sure

proper blower speed has been selected.

The motor is turned on through two different routes. The first

occurs when thermostat calls for the fan in cooling, heat

pump, or fan−only mode. A 24−Vac signal is sent to relay,

causing relay to close its normally open contacts, turning fan

on.

The second occurs when there is a call for electric heat. A

24−Vac signal is sent to heater sequencer/relay, causing it to

close, directing 230V through the normally closed contact of

fan relay, turning fan on. The fan remains on until

sequencer/relay opens.

If motor does not run, test motor for an open winding or a

winding shorted to motor case. If either is present, replace

motor.

FMA4X, WAXA

The FMA4X and WAXA motor is five−speed direct drive. The

cooling speed tap is selected by connecting the green wire to

the desired motor tap number indicated on the motor plug.

For the electric heat fan speed selection connect the white

wire to the desired motor tap number indicated on the motor

plug.

The blower motor in this unit has blower−on and blower−off

delays. The blower−on delay is 0−30 seconds and will keep

the motor running after a heating or cooling call ends.

If motor does not run, test motor for an open winding or a

winding shorted to motor case. If either is present, replace

motor.

ELECTRIC HEATER SERVICE

Service can be completed with heater in place. Shut off

power before servicing.

A. Limit Switch

Refer to Electric Heater Kit Function and Troubleshooting

section of this manual.

B. Sequencer

Refer to Electric Heater Kit Function and Troubleshooting

section of this manual.

C. Transformer

A 40−VA transformer supplies 24−V power for control circuit.

Check for 208/230V on primary side of transformer. If present,

check for 24V on secondary side.

NOTE: Transformer is fused. Do not short circuit.

D. Fan Relay

Relay coil is 24−V. Check for proper control voltage. Replace

relay if faulty.

CLEANING OR REPLACING REFRIGERANT

FLOW−CONTROL DEVICE

FMA4P, WAMA

The FMA4P and WAMA piston can be removed and cleaned

if believed to be plugged. This unit’s piston is unique and

replacements are available from FAST.

The filter drier should be located on the liquid line at the

indoor unit to prevent particulate from plugging the piston.

FMA4X, WAXA

The FMA4X and WAXA fan coils use an R−410A TXV. The

TXV’s are preset at the factory and do not need adjustment

for reliable operation. Reference the outdoor unit instructions

to properly charge the unit to the correct subcooling. For

optimal performance, adjust the TXV so that 6º F of

superheat is measured at the outdoor unit’s vapor service

valve when the indoor return air is 80ºF DB/67ºF WB and

outdoor ambient is 82ºF DB. To increase superheat turn the

TXV adjustment stem clockwise no more than one rotation at

a time. After an adjustment is made, wait until the superheat

temperature has been stable for 15 minutes before making

further adjustments.

SEQUENCE OF OPERATION

A. Condensing Unit

COOLING

When thermostat calls for cooling, the circuit between R and

G is complete and single−pole single−throw relay FR is

energized. The normally open contacts close causing blower

to operate.

The circuit between R and Y is also complete. This

completed circuit causes contactor in outdoor unit to close

which starts compressor and outdoor fan.

HEATING

When thermostat calls for heating and FAN switch is set on

AUTO, the circuit between R and W is complete. The heater

sequence SEQ is energized which closes contacts of relay.

There will be a time delay. This completed circuit energizes all

heating elements HTR and blower motor.

B. Heat Pump

COOLING

On a call for cooling, the thermostat makes circuits R−O, R−Y,

and R−G. Circuit R−O energizes reversing valve, switching it

to cooling position. Circuit R−Y energizes contactor starting

outdoor fan motor and compressor. Circuit R−G energizes

indoor unit blower relay starting indoor blower motor.

When thermostat is satisfied, its contacts open de−energizing

contactor reversing valve and blower relay. This stops

compressor and fan motors.

HEATING

On a call for heating, the thermostat makes circuits R−Y and

R−G. Circuit R−Y energizes contactor starting outdoor fan

motor and compressor. Circuit R−G energizes indoor blower

relay starting blower motor.

Should temperature continue to fall, R−W circuit is made

through second−stage room thermostat bulb. Circuit R−W

energizes a sequencer bringing on supplemental electric

heat.

When thermostat is satisfied, its contacts open de−energizing

contactor and sequencer. All heaters and motors should stop.

SERVICE AND MAINTENANCE FAN COILS

18 496 08 8001 00

Specifications subject to change without notice.

Figure 11 −FMA4, WAMA, WAXA (sizes 18 & 24) Expanded View−Case

18K & 24K Case

A13135B

Figure 12 −FMA4, WAMA, WAXA (sizes 18 & 24) Expanded View−Duct Components, Blower & Electrical Parts

A13136

SERVICE AND MAINTENANCE FAN COILS

496 08 8001 00 19

Specifications subject to change without notice.

Figure 13 −FMA4, WAMA, WAXA (sizes 18 & 24) Expanded View−Evaporator Parts & Drain Pan

(FMA4X & WAXA use TXV, not shown)

A13137B

Figure 14 −FMA4, WAMA, WAXA (sizes 30 & 36) Expanded View−Case

A13138B

SERVICE AND MAINTENANCE FAN COILS

20 496 08 8001 00

Specifications subject to change without notice.

Figure 15 −FMA4, WAMA, WAXA (sizes 30 & 36) Expanded View−Duct Components, Blower & Electrical Parts

A13139

Figure 16 −FMA4, WAMA, WAXA (sizes 30 & 36) Expanded View−Evaporator Parts & Drain Pan

A13140

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