Greenheck Dgx User manual

Packaged DX Module for Make-Up Air

Installation, Operation and Maintenance Manual

Please read and save these instructions for future reference. Read carefully before attempting to assemble,

install, operate or maintain the product described. Protect yourself and others by observing all safety

information. Failure to comply with instructions could result in personal injury and/or property damage!

Only qualiﬁed personnel should install and maintain

this system. Personnel should have a clear

understanding of these instructions and should

be aware of general safety precautions. Improper

installation can result in electric shock, possible injury

due to coming in contact with moving parts, as well as

other potential hazards. Other considerations may be

required if high winds or seismic activity are present.

If more information is needed, contact a licensed

professional engineer before moving forward.

1. Follow all local electrical and safety codes, as

well as the National Electrical Code (NEC), the

National Fire Protection Agency (NFPA), where

applicable. Follow the Canadian Electric Code

(CEC) in Canada.

2. Unit must be securely and adequately grounded.

3. Verify that the power source is compatible with

the equipment.

4. Never open access doors to the unit while it is

running.

General Safety Information

DANGER

• Always disconnect power before working on or

near this equipment. Lock and tag the disconnect

switch or breaker to prevent accidental power up.

• If this unit is equipped with optional gas

accessories, turn off gas supply whenever power

is disconnected.

CAUTION

This unit is equipped with a compressed refrigerant

system. If a leak in the system should occur,

immediately evacuate and ventilate the area. An

EPA Certified Technician must be engaged to make

repairs or corrections. Refrigerant leaks may also

cause bodily harm.

CAUTION

When servicing the unit, the internal components

may be hot enough to cause pain or injury. Allow

time for cooling before servicing.

Recognized Component

Part #474681

Packaged DX Module

As used in Greenheck models

•DGX

•IGX

•MSX

2Packaged DX Module for Make-Up Air Unit

Receiving

This Packaged DX Module is installed as a component

of a make-up air unit and does not require any special

handling. Refer to the Receiving portion of the unit

IOM for complete instructions on receiving, unpacking

and handling.

Unpacking

The Packaged DX unit is shipped as a complete

installed unit. Protective coverings have been installed

on the face of the condenser coil that should be left in

place until installation of the unit is complete. The only

item that was shipped loose with the unit is the P Trap

kit (see below right). Verify that the P Trap kit has been

received. Refer to Unpacking instructions in unit IOM.

Handling

Units are to be rigged and moved by the lifting

brackets provided. Do not forklift. Refer to the

Handling portion of the unit IOM for complete

instructions on handling.

Hoisting

All units equipped with a Packaged DX Module are

provided with either four or six lifting lugs. When the

unit is being hoisted, all of the provided lugs must

be used for support. Four lifting lugs are on the four

corners of the unit, located at the base. In addition,

there may be two more lifting lugs located at the top

of the unit. The locations of those two top lugs varies

somewhat from unit to unit. Use spreader bars to

prevent damage to the cabinet.

Use spreader bars as shown to prevent damage to the

cabinet. If top-mounted lifting lugs are present, they

must be used in conjunction with the bottom-mounted

lifting lugs when hoisting the unit.

Use lifting lugs on

all four corners.

Lifting Details

Table of Contents

Receiving ...................................2

Unpacking...................................2

Handling ....................................2

Hoisting.....................................2

Storage .....................................3

Inspection and Maintenance During Storage .......3

Models and Capacities ........................3

Model Number ...............................3

Installation Issues

Provide and Install Switch S4 .................3

Install Condensate Drain (P Trap) ..............3

Service Clearances..........................3

Additional Clearances for Packaged DX Units ....3

Product Overview.............................4

Compressed Refrigerant .....................4

Safety Listing ..............................4

Supplemental Installation, Operation and

Maintenance Manuals .......................4

Subassemblies ...............................4

Coils .....................................4

Dampers ..................................4

DX System ................................4

Factory Installed Refrigeration System

Components ...............................5-6

Compressor Compartment Components ..........7

Additional Control Components ...............7

Typical Wiring Diagram ......................8-9

Component Locations ........................10

Sequence of Operation .......................10

Control Sequence..........................10

Control Sequence/Variable Air Volume (optional). 11

Pre Start-Up

Pre Start-Up Checklist ......................11

Special Tools Required: .....................11

Start-Up Checklist ......................11-12

Electrical Start-Up Checklist .................12

Refrigeration System Start-Up Checklist .......12

Troubleshooting - Refrigeration Circuit........13-16

Routine Maintenance .........................17

Monthly ..................................17

Annually .................................17

Maintenance Log .........................18-19

Warranty ...................................20

Packaged DX Module for Make-Up Air Unit

Storage

Units are protected against damage during shipment.

If the unit cannot be installed and operated

immediately, precautions need to be taken to prevent

deterioration of the unit during storage. The user

assumes responsibility of the unit and accessories

during storage. The manufacturer will not be

responsible for damage during storage. The following

suggestions are provided solely as a convenience to

the user.

Inspection and Maintenance During

Storage

While in storage, inspect units once per month. Keep

a record of inspection and maintenance performed. If

moisture or dirt accumulations are found on the parts,

the source should be located and eliminated. At each

inspection, rotate all moving parts by hand ten to

ﬁfteen revolutions to distribute lubricant on motor and

bearings. If paint deterioration begins, consideration

should be given to touch-up or repainting. Units with

special coatings may require special techniques for

touch-up or repair.

Machined parts coated with rust preventative should

be restored to good condition promptly if signs of

rust occur. Immediately remove the original rust

preventative coating with petroleum solvent and clean

with lint-free cloths. Polish any remaining rust from the

surface with crocus cloth or ﬁne emery paper and oil.

Do not destroy the continuity of the surfaces. Wipe

clean thoroughly with Tectyl® 506 (Ashland, Inc.) or

the equivalent. For hard to reach internal surfaces or

for occasional use, consider using Tectyl® 511M Rust

Preventative or WD-40® or the equivalent.

Models and Capacities

The Packaged DX Module for Make-Up Air Units is

manufactured in three different platform sizes, each

of which has several

different output tonnage

options. Examine

shipping documents to

verify correct model of

the module as received.

Model Number

A metal plate is located on the ﬁxed panel access

to the control center. The plate is marked with the

Platform Type and Tonnage (for example, H12-6).

Record the model number here:

Installation Issues

Provide and Install Switch S4

Each Packaged DX unit requires an On/Off switch to

enable the unit to run. This is a user supplied switch

that may be a toggle switch mounted in a 2 x 4 inch

electric box (mounted in a position chosen by the

user), or it may be a simple jumper or even a control

switch installed in a remote control panel supplied by

the factory. See also “Additional Control Components”

on page 7 of this manual.

Install Condensate Drain (P Trap)

The only installation step that

is speciﬁc to the DX module is

installation and priming of the

engineered P trap. Locate the

P trap kit that was shipped

with the unit and install the

kit in accordance with the

enclosed instructions.

Service Clearances

All make-up air units require minimum clearances on

all sides for routine maintenance. Filter replacement,

drain pan inspection and cleaning, fan bearing

lubrication and belt adjustment are all examples of

routine maintenance that must be performed. Blower

and motor assemblies and coil and ﬁlter sections

are always provided with a service door or panel for

proper component access. Clearances for component

removal may be greater than the service clearances.

Refer to submittal drawings for these clearance

dimensions. See also Page 4 of this manual.

Additional Clearances for Packaged DX

Units

Packaged DX units require additional service

clearance because they must have unrestricted

air movement around the condenser coil and

condenser fans. Hot air is being discharged from

the condenser fans during operation and the more

clearance available, the better the chance of avoiding

recirculation or coil starvation. This unit should never

be placed under an overhang or inside a building. A

minimum of 48 inches above the condenser fans is

recommended. See Page 4 of this manual.

Platform Tonnage

H12 3,5,6,8

H22 7,9,10

H32 10,12,16

4Packaged DX Module for Make-Up Air Unit

Clearances (continued)

Product Overview

The Greenheck Packaged DX Module for make-up

air is a horizontally conﬁgured unit that is installed as

a package in make-up air units and is designed for

outdoor installations. The Packaged DX Module is

used to temper the air that is supplied to the building.

The make-up air unit is designed to provide sufﬁcient

air to replace air that is exhausted from the building

and this module is designed to provide necessary

cooling.

The DX system comes fully charged with R-410A

refrigerant from the factory and is ready for operation

upon arrival.

Units may be supplied with one or two compressors

based on required cooling capacity. All units

with multiple compressors allow for staging of

compressors to meet a wider range of outdoor

air loads while reducing the number of cycles per

compressor.

Compressed Refrigerant

All packaged DX modules are charged with

environmentally friendly R-410A compressed

refrigerant. Do not use tools or parts designed for

other refrigerants on this unit.

Safety Listing

Make-up air units are listed per ANSI/UL 1995, Heating

and Cooling Equipment and are ETL Certiﬁed.

Supplemental Installation, Operation and

Maintenance Manuals

Refer to the Installation, Operation and Maintenance

manual for the Make-Up Air unit for additional

information.

Subassemblies:

Coils

Every module is supplied with a single DX evaporator

coil. If there is only one cooling circuit, then the

DX coil is not divided. If two cooling circuits are

speciﬁed, then the DX coil will be a split-face. A

single condensor coil is attached to the exterior of the

module. If more than one cooling circuit is present,

that condensor coil will be of split-face conﬁguration.

Dampers

There is only one damper that may be installed in a

PDX module. That is an inlet damper and it will only

be found when the module is installed in either a

Greenheck model IGX or MSX that was not ordered

with an inlet damper module.

DX System

The DX system in the module is a complete, sealed

unit with compressed R-410A refrigerant. It consists of

one or two compressors, evaporator and condenser

coils and the following integral components:

• expansion valves

• liquid line lter-drier

• service / charging valves

• moisture indicating sight glass

• crankcase heater on each compressor

Each DX system incorporates the following:

• high pressure manual reset cutout

• low pressure auto-reset cutout

Outdoor

Air Intake

Unit Control Center

Condenser Fans

and

Condenser Coil

Indirect Gas-Fired

Furnace

42 inches clearance

48 inches clearance

36 inches clearance

End view of make-up air unit

with Packaged DX

END VIEW OF MAKE-UP AIR UNIT

WITH PACKAGED DX

Minimum 48 inches clearance

Minimum 42 inches

clearance

Condenser Coil

Condenser Fans

Packaged DX Module for Make-Up Air Unit

Factory Installed Refrigeration System Components

1. Thermostatic Expansion Valve (TXV)

Each unit is equipped with a Thermal

Expansion Valve on each refrigerant

circuit. The valve controls the ﬂow

of liquid refrigerant entering the

evaporator coil by maintaining a

constant, factory set superheat of

10°F. The valve is adjustable and is

located on the side of the evaporator

coil and can be accessed through the

coil panel access door.

2. Refrigerant Distributor

Attached to the TXV is a refrigerant distributor.

The refrigerant distributor evenly distributes the

refrigerant to each circuit of the evaporator coil to

provide optimum performance.

3. Evaporator Coil

The coil is located in the supply airstream. In the

DX system, the liquid refrigerant is expanded in the

TXV and it then ﬂows through the evaporator coil.

The refrigerant enters the coil as a low temperature

liquid/gas where it eventually boils into a low

temperature, low pressure gas prior to going

into the compressor. As the refrigerant passes

through the evaporator coil, it absorbs heat from

the airstream. To ensure proper operation, the coil

surface must be cleaned so that air movement over

the coil provides the necessary heat transfer.

4. Low Limit Pressure Switch

The unit includes a low limit pressure switch

(located in the compressor compartment). The

switch is installed in the suction line and shuts off

the DX system when the suction pressure drops to

50 psi for R-410A. The switch has a built in auto-

Evaporator Coil

Condenser Coil

Service Valve for Subcooling Gauge/

High Side Pressure Drop

Circuit A

Service Valve for

Superheat and Low

Side Pressure

Pressure Port for

Troubleshooting

Reheat Valves

High Side

Pressure Drop

reset, which will close the circuit and allow the

system to run when the pressure increases back to

90 psi for R-410A.

5. Compressors

Each unit will have either one or two high-efﬁciency

scroll-type compressors. The scroll in each

compressor compresses the refrigerant in a

gaseous state to a high temperature, high pressure

gas.

Compressor Protective Devices:

Thermal Overload: Each compressor is

equipped with an auto reset thermal overload.

High Temp Protection: Internal devices within

the compressor protect it against excessively

high discharge gas temperatures.

Crankcase Heater: Liquid refrigerant is

incompressible. Therefore, a crankcase heater is

installed around each compressor to boil off any

liquid refrigerant that may be absorbed into the

oil during idle periods. System power energizes

the heater; the heater should be allowed to run

24 hours prior to compressor start-up. See Start-

Up Checklist, page 9.

6. Condensing Coil

Each unit contains a condensing coil mounted

on the exterior of the unit. High temperature, high

pressure gas from the compressor enters the coil

and is eventually cooled into a high temperature,

high pressure liquid. The condensing fans move

air over the coil which pulls the heat out of the

refrigerant. To ensure proper operation, the coil

must be cleaned so that air movement over the coil

provides the necessary heat transfer.

6Packaged DX Module for Make-Up Air Unit

Factory Installed Components

(continued)

7. Condenser Fans

The unit is equipped with one, two or three

direct-drive condensing fans. The fans provide

the necessary airﬂow to cool the refrigerant in

the condensing coil. The motors are equipped

with sling protection to guard against water

penetration, and are thermally protected. The

thermal overloads shut down the condensing

fans and will automatically reset.

8. High Limit Pressure Switch

To safely shut down the DX

system in case of an increase

in refrigerant pressure,

a high limit pressure

switch is included. The switch is located in

the compressor compartment. It trips when

refrigerant pressure increases to 575 psi for

R-410A in the discharge line and can only be

manually reset when the pressure drops below

420 psi. Typically, if the high pressure limit switch

trips, a failure in the system has occurred and

more investigation is needed to determine the

underlying problem.

9. Liquid Line Filter-Drier

The liquid line ﬁlter-drier prevents moisture and

foreign matter from entering the expansion valve.

10. Moisture Indicating Sight Glass

Moisture in a DX system can freeze in the

system or dilute the compressor oil. A moisture

indicating sight glass is

provided for each refrigerant

circuit. During normal

operating conditions, the sight

glass should typically be liquid. Some gas is

acceptable, but excessive bubbles may indicate

improper charge or a leak in the system. A

green dot means that moisture is below a safe

operation level in the refrigerant, while a yellow

dot indicates moisture has been introduced into

the system and needs to be dealt with.

11-13. Access Ports

For easy measurement and charging access,

several ports are provided through the

system. These can be used to measure

system pressure and also charge or evacuate

the system. Most ports are located in the

compressor compartment for easy access.

Packaged DX Module for Make-Up Air Unit

Compressor Compartment

Components

Each Packaged DX module has a complete set of

compressor contactors, condenser fan contactors,

relays and certain integral safety controls located in

the module.

1. Power Distribution Block - ﬁeld-supplied power

from main disconnect switch is terminated here.

2. Phase Monitor has jumpers going to power

distribution block)

3. Transformer provides 24 VAC to various low

voltage devices including the Phase Monitor

and to Low Voltage Terminal Strip in compressor

compartment.

4. Relays RC1 and RC2 are wired to the control

center in the compressor compartment.

5. Low Voltage Terminal Strip - Switch S4

terminates here.

6. Thermostat TS5 monitors outdoor air temperature

and turns the DX unit on or off.

7. Inlet Air Sensor monitors the incoming air

temperature and will disable the DX unit if ambient

temperatures are too low.

Additional Control Components

In addition to the control components located in the

PDX module, various high- and low-voltage circuits

are found in the Make-Up Air Unit control center. See

the unit-speciﬁc wiring diagram (found in the unit

control center) for complete information.

Phase Monitor constantly checks for

loss of a phase, phase unbalance or

phase reversal. It requires 24 VAC to

operate. When a fault is detected, it

cuts off the power supply to the low

voltage terminal strip, disabling all

motors. It has two LED indicator lights,

showing “on” and “fault”.

Switch S4 (not shown) is terminated

on Low Voltage Terminal Strip 5 above.

S4 is ﬁeld-supplied and ﬁeld-installed

unless ordered from the factory. See the

unit speciﬁc wiring diagram.

Thermostat TS5 monitors outdoor air

temperature. It is ﬁeld-adjustable. If

there is more than one cooling circuit,

an additional controller for the second

stage will be provided.

Typical PDX Compressor Compartment

Typical Unit Control Center

Electrical Components

1. High Voltage Terminal Strip

2. Compressor Relays

3. Condenser Fan Contactor

4A. Compressor Contactor (Circuit A)

4B. Compressor Contactor (Circuit B)

5. Low Voltage Terminal Strip

6. High Limit Safety Control – Direct Gas-Fired

units only

Refrigeration Components

7A. Compressor (Circuit A)

7B. Compressor (Circuit B)

8A. High Pressure Sensor (Circuit A, Manual Reset)

8B. High Pressure Sensor (Circuit B, Manual Reset)

9A. Thermostatic Expansion Valve (TXV) (Circuit A)

9B. Thermostatic Expansion Valve (TXV) (Circuit B)

10A. Refrigerant Distributor (Circuit A)

10B. Refrigerant Distributor (Circuit B)

11. Condensate Drain (P trap here)

8Packaged DX Module for Make-Up Air Unit

CAUTION

UNIT SHALL BE GROUNDED IN ACCORDANCE WITH N.E.C.

POWER MUST BE OFF WHILE SERVICING.

NOTES

USE COPPER CONDUTORS ONLY

60° C FOR TERMINALS RATED LESS THAN 100 AMPS.

75° C FOR TERMINALS RATED 100 AMPS OR MORE.

FIELD CONTROL WIRING RESISTANCE SHOULD

NOT EXCEED 0.75 OHM.

FIELD WIRED

FACTORY SUPPLIED AND WIRED

LEGEND

WIRE COLOR CODE

GD11N601A013C10NM08

Wiring Diagram Code:

BK BLACK BL BLUE BR BROWN

GY GRAY LT BL LIGHT BLUE O ORANGE

PK PINK PR PURPLE R RED

W WHITE Y YELLOW

Wiring Template: M07

AMP AMPLIFIER

CC# COMPRESSOR CONTACTOR

CF1 CONDENSER FAN CONTACTOR

CH# CRANK CASE HEATER

D1 INLET DAMPER

DB1 DISTRIBUTION BLOCK

DS1 MAIN DISCONNECT SWITCH

FSC FIRE SYSTEM CONTACT

FSG FLAME SAFE GUARD

FU# FUSE

HLC# HIGH LIMIT CONTROL

HPS# HIGH PRESSURE SWITCH

LPS# LOW PRESSURE SWITCH

MOD MODULATING VALVE

M# MOTOR

OL# MOTOR OVERLOAD

PM PHASE MONITOR

PS2 AIR PROVING SWITCH

R10 COMP#1 INTERLOCK RELAY

R11 COMP#2 INTERLOCK RELAY

RC# COOLING STAGE RELAYS

RF FAN RELAY

RH HEAT RELAY

S2 SUPPLY FAN SWITCH

S4 HEAT AND COOL SWITCH

ST# MOTOR STARTER

TR# TRANSFORMER

TS1 OUTDOOR AIR SENSOR

TS2 DISCHARGE AIR SENSOR

TS4 INLET AIR SENSOR

TS5 OUTDOOR AIR SENSOR

TS9 LOW DISCHARGE TEMP SENSOR

V2 MAIN VALVE

TR1

75 VA

DS1

SUPPLY FAN

MAIN POWER

TO UNIT - 460V

R X

UNIT CONTROL

R10

A1A2

BL BL W

HPS1

LPS1

RC1

1411

PDX CONTROL

CC1

A2 A1

R10

COMPONENTS LOCATED IN COMPRESSOR COMPARTMENT

COMPONENTS LOCATED IN COOLING COIL MODULE CONTROL CENTER

O O O

R11

A1A2

WBL

HPS2

LPS2

CC2

A2 A1

R11

CC2

RC2

1411

R R

BR BR BR

CF1

A2 A1

CC1

R R

R X

HLC1 FSG

PS2

252423

NCNO C

PS2

SENSOR

GND

V1 37

SPARK

14 26

DG FURNACE CONTROL

TR2

BL Y

BK W

24 VAC

40 VA

TR5

24 VAC

50 VA

3839

BK BK

112 111

7AMP

2 3

TS2

4 5

MOD

DISCHARGE STAT.

BL BLBK W

10 SEC

INT

HLC1 LOCATED

IN COOLING MODULE

CONTROL CENTER

111

112

ST1

T2L2

DB1

CC1

COMPRESSOR #1

CONDENSER FAN #1

CF1

CONDENSER FAN #2

CH1CH2

COMPRESSOR #2

142

141

CC2

24 VAC

Y-OUT

FSC

9695

ST1OL

ST1

A2 A1

R W

2 1

TS4(1)

R B PKPK

W1 A1A2

21 24

11 14

CCC NONONO

Jumper=Cool

Diff=5 Off=10

RC2

A2 A1

RC1

PR W

A2 A1

TS5

CNONONO

COM W

Jumper=Cool

Diff=5

TS5

SENSOR BK

24VAC

Typical Wiring Diagrams

Packaged DX Module for Make-Up Air Unit

CAUTION

UNIT SHALL BE GROUNDED IN ACCORDANCE WITH N.E.C.

POWER MUST BE OFF WHILE SERVICING.

NOTES

USE COPPER CONDUTORS ONLY

60° C FOR TERMINALS RATED LESS THAN 100 AMPS.

75° C FOR TERMINALS RATED 100 AMPS OR MORE.

FIELD CONTROL WIRING RESISTANCE SHOULD

NOT EXCEED 0.75 OHM.

FIELD WIRED

FACTORY SUPPLIED AND WIRED

LEGEND

WIRE COLOR CODE

GD11N601A013C10NM08

Wiring Diagram Code:

BK BLACK BL BLUE BR BROWN

GY GRAY LT BL LIGHT BLUE O ORANGE

PK PINK PR PURPLE R RED

W WHITE Y YELLOW

Wiring Template: M07

AMP AMPLIFIER

CC# COMPRESSOR CONTACTOR

CF1 CONDENSER FAN CONTACTOR

CH# CRANK CASE HEATER

D1 INLET DAMPER

DB1 DISTRIBUTION BLOCK

DS1 MAIN DISCONNECT SWITCH

FSC FIRE SYSTEM CONTACT

FSG FLAME SAFE GUARD

FU# FUSE

HLC# HIGH LIMIT CONTROL

HPS# HIGH PRESSURE SWITCH

LPS# LOW PRESSURE SWITCH

MOD MODULATING VALVE

M# MOTOR

OL# MOTOR OVERLOAD

PM PHASE MONITOR

PS2 AIR PROVING SWITCH

R10 COMP#1 INTERLOCK RELAY

R11 COMP#2 INTERLOCK RELAY

RC# COOLING STAGE RELAYS

RF FAN RELAY

RH HEAT RELAY

S2 SUPPLY FAN SWITCH

S4 HEAT AND COOL SWITCH

ST# MOTOR STARTER

TR# TRANSFORMER

TS1 OUTDOOR AIR SENSOR

TS2 DISCHARGE AIR SENSOR

TS4 INLET AIR SENSOR

TS5 OUTDOOR AIR SENSOR

TS9 LOW DISCHARGE TEMP SENSOR

V2 MAIN VALVE

TR1

75 VA

DS1

SUPPLY FAN

MAIN POWER

TO UNIT - 460V

R X

UNIT CONTROL

R10

A1A2

BL BL W

HPS1

LPS1

RC1

1411

PDX CONTROL

CC1

A2 A1

R10

COMPONENTS LOCATED IN COMPRESSOR COMPARTMENT

COMPONENTS LOCATED IN COOLING COIL MODULE CONTROL CENTER

O O O

R11

A1A2

WBL

HPS2

LPS2

CC2

A2 A1

R11

CC2

RC2

1411

R R

BR BR BR

CF1

A2 A1

CC1

R R

R X

HLC1 FSG

PS2

252423

NCNO C

PS2

SENSOR

GND

V1 37

SPARK

14 26

DG FURNACE CONTROL

TR2

BL Y

BK W

24 VAC

40 VA

TR5

24 VAC

50 VA

3839

BK BK

112 111

7AMP

2 3

TS2

4 5

MOD

DISCHARGE STAT.

BL BLBK W

10 SEC

INT

HLC1 LOCATED

IN COOLING MODULE

CONTROL CENTER

111

112

ST1

DB1

CC1

COMPRESSOR #1

CONDENSER FAN #1

CF1

CONDENSER FAN #2

CH1CH2

COMPRESSOR #2

142

141

CC2

24 VAC

Y-OUT

FSC

9695

ST1OL

ST1

A2 A1

R W

2 1

TS4(1)

R B PKPK

W1 A1A2

21 24

11 14

CCC NONONO

Jumper=Cool

Diff=5 Off=10

RC2

A2 A1

RC1

PR W

A2 A1

TS5

CNONONO

COM W

Jumper=Cool

Diff=5

TS5

SENSOR BK

24VAC

CAUTION

UNIT SHALL BE GROUNDED IN ACCORDANCE WITH N.E.C.

POWER MUST BE OFF WHILE SERVICING.

NOTES

USE COPPER CONDUTORS ONLY

60° C FOR TERMINALS RATED LESS THAN 100 AMPS.

75° C FOR TERMINALS RATED 100 AMPS OR MORE.

FIELD CONTROL WIRING RESISTANCE SHOULD

NOT EXCEED 0.75 OHM.

FIELD WIRED

FACTORY SUPPLIED AND WIRED

LEGEND

WIRE COLOR CODE

GD11N601A013C10NM08

Wiring Diagram Code:

BK BLACK BL BLUE BR BROWN

GY GRAY LT BL LIGHT BLUE O ORANGE

PK PINK PR PURPLE R RED

W WHITE Y YELLOW

Wiring Template: M07

AMP AMPLIFIER

CC# COMPRESSOR CONTACTOR

CF1 CONDENSER FAN CONTACTOR

CH# CRANK CASE HEATER

D1 INLET DAMPER

DB1 DISTRIBUTION BLOCK

DS1 MAIN DISCONNECT SWITCH

FSC FIRE SYSTEM CONTACT

FSG FLAME SAFE GUARD

FU# FUSE

HLC# HIGH LIMIT CONTROL

HPS# HIGH PRESSURE SWITCH

LPS# LOW PRESSURE SWITCH

MOD MODULATING VALVE

M# MOTOR

OL# MOTOR OVERLOAD

PM PHASE MONITOR

PS2 AIR PROVING SWITCH

R10 COMP#1 INTERLOCK RELAY

R11 COMP#2 INTERLOCK RELAY

RC# COOLING STAGE RELAYS

RF FAN RELAY

RH HEAT RELAY

S2 SUPPLY FAN SWITCH

S4 HEAT AND COOL SWITCH

ST# MOTOR STARTER

TR# TRANSFORMER

TS1 OUTDOOR AIR SENSOR

TS2 DISCHARGE AIR SENSOR

TS4 INLET AIR SENSOR

TS5 OUTDOOR AIR SENSOR

TS9 LOW DISCHARGE TEMP SENSOR

V2 MAIN VALVE

TR1

75 VA

DS1

SUPPLY FAN

MAIN POWER

TO UNIT - 460V

R X

UNIT CONTROL

R10

A1A2

BL BL W

HPS1

LPS1

RC1

1411

PDX CONTROL

CC1

A2 A1

R10

COMPONENTS LOCATED IN COMPRESSOR COMPARTMENT

COMPONENTS LOCATED IN COOLING COIL MODULE CONTROL CENTER

O O O

R11

A1A2

WBL

HPS2

LPS2

CC2

A2 A1

R11

CC2

RC2

1411

R R

BR BR BR

CF1

A2 A1

CC1

R R

R X

HLC1 FSG

PS2

252423

NCNO C

PS2

SENSOR

GND

V1 37

SPARK

14 26

DG FURNACE CONTROL

TR2

BL Y

BK W

24 VAC

40 VA

TR5

24 VAC

50 VA

3839

BK BK

112 111

7AMP

2 3

TS2

4 5

MOD

DISCHARGE STAT.

BL BLBK W

10 SEC

INT

HLC1 LOCATED

IN COOLING MODULE

CONTROL CENTER

111

112

ST1

DB1

CC1

COMPRESSOR #1

CONDENSER FAN #1

CF1

CONDENSER FAN #2

CH1CH2

COMPRESSOR #2

142

141

CC2

24 VAC

Y-OUT

FSC

9695

ST1OL

ST1

A2 A1

R W

2 1

TS4(1)

R B PKPK

W1 A1A2

21 24

11 14

CCC NONONO

Jumper=Cool

Diff=5 Off=10

RC2

A2 A1

RC1

PR W

A2 A1

TS5

CNONONO

COM W

Jumper=Cool

Diff=5

TS5

SENSOR BK

24VAC

10 Packaged DX Module for Make-Up Air Unit

Sequence of Operation

The compressors are energized by an outdoor air

thermostat TS5, located in the unit control center. The

thermostat sensor is located in the intake airstream

upstream of the DX coil. The thermostat can be a

single or dual stage thermostat depending on the

number of compressors. The ﬁrst stage of cooling

will energize when the outdoor air temperature rises

above the thermostat set point plus the differential.

The thermostat is factory set at 80°F with a differential

of 5°F but can be ﬁeld adjusted. The second

stage of cooling will energize when the outdoor air

temperature rises above the second stage offset plus

the differential. The second stage offset is factory set

at 10°F and the second stage differential is set at 5°F.

See the chart below for a graphical representation of

the control operation.

To summarize the

cooling controls,

the ﬁrst stage of

cooling will turn

on at 85°F and the

second stage of

cooling will turn

on at 95°F. The

second stage of

cooling will turn

off at 90°F and

the ﬁrst stage of

cooling will turn

off at 80°F.

Control Sequence

1. Heating/Cooling switch (S4) is closed between

terminal R and Y1.

2. N.O. contact on fan relay (RF) is energized and

closed.

3. When the outdoor air temperature is above the

set point plus the differential power passes

through N.O. contacts on outdoor air thermostat

(TS5) and energizes the cooling relay (RC1).

4. When the pressure switches LPS (refrigerant

low pressure switch) and HPS (refrigerant

high pressure switch) are in their normal state

relay R10 will energize. Starting the ﬁrst stage

compressor contactor.

5. When the outdoor air temperature is above the

second stage offset plus the differential power

passes through N.O. contacts on outdoor air

thermostat (TS5) and energizes the cooling relay

(RC2).

6. When the pressure switches LPS and HPS

(refrigerant high pressure switch) are in their

normal state relay R11 will energize, starting the

second stage compressor contactor.

Model DGX Make-Up Air Unit

Outdoor

Air Intake

Model DGX Make-Up Air Unit

Unit Control Center

Condenser Fans

and Condenser Coil

Evaporator Coil

Direct Gas-Fired Burner

Model IGX Make-Up Air Unit

Outdoor

Air Intake

Model IGX Make-Up Air Unit

Unit Control Center

Condenser Fans

and Condenser Coil

Evaporator Coil

Indirect Gas-Fired

Furnace

Model MSX Make-Up Air Unit

with Electric Heat

Outdoor

Air Intake

Model MSX with Electric Heat

Unit Control

Center

Condenser Fans

and Condenser Coil

Evaporator Coil

Setpoint

Temperature

(factory set at 80° F)

Adjustable

Differential

Adjustable

Differential

OFF

OFFSET

(factory set

at 10° F)

(+5° F)

(+10° F)

FIRST

STAGE

COOLING

SECOND

STAGE

COOLING

Make-Up Air Units showing

Component Locations

Sequence of Operation

The compressors are energized by an outdoor air

thermostat TS5, located in the unit control center. The

thermostat sensor is located in the intake airstream

upstream of the DX coil. The thermostat can be a

single or dual stage thermostat depending on the

number of compressors. The ﬁrst stage of cooling

will energize when the outdoor air temperature rises

above the thermostat set point plus the differential.

The thermostat is factory set at 80°F with a differential

of 5°F but can be ﬁeld adjusted. The second

stage of cooling will energize when the outdoor air

temperature rises above the second stage offset plus

the differential. The second stage offset is factory set

at 10°F and the second stage differential is set at 5°F.

See the chart below for a graphical representation of

the control operation.

To summarize the

cooling controls,

the ﬁrst stage of

cooling will turn

on at 85°F and the

second stage of

cooling will turn

on at 95°F. The

second stage of

cooling will turn

off at 90°F and

the ﬁrst stage of

cooling will turn

off at 80°F.

Outdoor

Air Intake

Model DGX Make-Up Air Unit

Unit Control Center

Condenser Fans

and Condenser Coil

Evaporator Coil

Direct Gas-Fired Burner

Outdoor

Air Intake

Model IGX Make-Up Air Unit

Unit Control Center

Condenser Fans

and Condenser Coil

Evaporator Coil

Indirect Gas-Fired

Furnace

Outdoor

Air Intake

Model MSX with Electric Heat

Unit Control

Center

Condenser Fans

and Condenser Coil

Evaporator Coil

Setpoint

Temperature

(factory set at 80° F)

Adjustable

Differential

Adjustable

Differential

OFF

OFFSET

(factory set

at 10° F)

(+5° F)

(+10° F)

FIRST

STAGE

COOLING

SECOND

STAGE

COOLING

Make-Up Air Units showing

Component Locations

Packaged DX Module for Make-Up Air Unit

Control Sequence - Variable Air Volume

(optional)

1. Heating/Cooling switch (S4) is closed between

terminal R and Y1.

2. N.O. contact on fan relay (RF) is energized and

closed.

3. When the outdoor air temperature is above the

set point plus the differential power passes

through N.O. contacts on outdoor air thermostat

(TS5) and energizes the cooling relay (RC1).

4. When the pressure switches LPS (refrigerant

low pressure switch) and HPS (refrigerant

high pressure switch) are in their normal state

relay R10 will energize. Starting the ﬁrst stage

compressor contactor.

5. When the outdoor air temperature is above the

second stage offset plus the differential power

passes through N.O. contacts on outdoor air

thermostat (TS5) and energizes the cooling relay

(RC2).

6. When the pressure switches LPS and HPS

(refrigerant high pressure switch) are in their

normal state relay R11 will energize, starting the

second stage compressor contactor.

7. When the discharge air temperature drops below

the low temperature set point (TS9) factory set

at 55°F, the second stage compressor contactor

will de-energize, turning off the second stage

compressor.

8. The second stage compressor will re-energize

when the discharge air temeprature rises above

75°F.

Pre Start-Up

Pre Start-Up Checklist

(Complete prior to application of power)

Verify proper drain trap installation. Refer to

Condensate Drain in Installation Concerns section.

Fill drain with water.

Look over the piping system. Inspect for oil at

all tubing connections. Oil typically highlights a

leak in the system. If a leak is present, refer to the

maintenance section in this manual.

Inspect all coils within the unit. Fins may get

damaged in transit or during construction. Carefully

straighten ﬁns with a ﬁn comb.

Check condensing fans for any damage or

misalignment. Spin the blades and make sure they

are free turning without any resistance.

Each compressor has a crankcase heater which

must have power supplied to it at least 24hours

prior to start-up. If start-up is scheduled in

24hours, unlock the power disconnect and

energize the unit without applying power to

terminal Y1.

Start-Up Checklist

The unit will be in operational mode during start-up.

Use necessary precautions to avoid injury. All data

must be collected while the unit is running. In order to

measure volts and amps, the control center door must

be open and the unit energized, using an adjustable

wrench to turn the disconnect handle.

After power has been applied

for 24 hours, verify that all

crankcase heaters are heating

properly. Either check the amp

draw on each heater or touch the

compressor near the top to verify

that the heater is warming the

compressor.

WARNING

Do not touch the heater. It will cause severe burns!

See image of crackcase heater.

Crankcase Heater

(silver colored band)

SPECIAL TOOLS REQUIRED

• Voltage Meter (with wire probes)

• Amperage Meter

• Pressure Gauges (refrigerant)

• Thermometer

• Tachometer

• Incline Manometer or equivalent

12 Packaged DX Module for Make-Up Air Unit

Start-Up Checklist

(continued)

CIRCUIT A

Compressor:

_______ L1 amps

_______ L2 amps

_______ L3 amps

_______ Crankcase Heater

Superheat _______Deg. F.

Should be between 8º and 12ºF.

Subcooling _______Deg. F.

Should be between 12º and 18ºF.

Discharge Pressure ________ PSIG

Discharge Line Temperature _______Deg. F.

Suction Line Pressure ________ PSIG

Suction Line Temperature _______Deg. F.

Moisture Indicating Sight Glass located on copper

tube liquid line

Bubbles Visible Yes / No

If bubbles are visible in sight glass, stop the start-up

process. Refrigerant charge may not be adequare.

Consult factory.

Color of Center Dot Green / Yellow

CIRCUIT B - if present

Compressor:

_______ L1 amps

_______ L2 amps

_______ L3 amps

_______ Crankcase Heater

Superheat _______Deg. F.

Should be between 8º and 12ºF.

Subcooling _______Deg. F.

Should be between 12º and 18ºF.

Discharge Pressure ________ PSIG

Discharge Line Temperature _______Deg. F.

Suction Line Pressure ________ PSIG

Suction Line Temperature _______Deg. F.

Moisture Indicating Sight Glass located on copper

tube liquid line

Bubbles Visible Yes / No

If bubbles are visible in sight glass, stop the start-up

process. Refrigerant charge may not be adequare.

Consult factory.

Color of Center Dot Green / Yellow

Compressors

Each DX unit is equipped with either one or two

compressors. Each compressor is part of a separate

refrigeration circuit.

NOTE

Refrigeration System Start-Up Checklist must be

performed by a Qualified Refrigeration Technician.

Outdoor Air Temperature __________ Deg. F.

Wet Bulb Reading or Dew Point or Outdoor Air

Relative Humidity (indicate which) ___________ % RH

Condensing Fan 1:

_______ L1 amps

_______ L2 amps

_______ L3 amps

 Condensing Fan 2:

_______ L1 amps

_______ L2 amps

_______ L3 amps

 Condensing Fan 3:

(if present)

_______ L1 amps

_______ L2 amps

_______ L3 amps

Apply power to terminal Y1 on the terminal strip. If

necessary, adjust thermostat TS5 to call for maximum

cooling.

Electrical Start-Up Checklist

Crankcase Heaters Working Yes / No

Check line voltage at unit disconnect

_______ L1-L2 volts

_______ L2-L3 volts

_______ L1-L3 volts

Correct fan rotation direction

Condenser Fans Yes / No

Refrigeration Start-Up Checklist

All motor(s) / compressor(s) have been checked for

rotation. If blower rotation is incorrect, wiring must

be changed at the disconnect to ensure all motor(s) /

compressor(s) are corrected.

CAUTION

Operation of scroll compressor(s) in this unit is

directional and the compressors will be damaged if

run in the wrong direction.

Packaged DX Module for Make-Up Air Unit

Symptom Possible Cause Corrective Action

Compressor will not

run or does not start

Open disconnect switch or circuit breaker. Close switch and/or breaker.

Compressor contactor not closing.

Check voltage to contactor coil,

transformer, slave relay, system. Replace

parts as necessary.

Blown fuse or tripped breaker. Check for reason and repair. Replace fuse

after correcting problem.

Low line voltage.

Check line voltage. If more than 10%

from compressor marking, correcting is

necessary.

Compressor motor protector open.

Motor thermal protector automatically

resets. Allow time (2 hrs) for compressor to

cool down so protector will reset. Restart

and check for reason overheat occurred.

Compressor defective.

Check motor for open circuit, short

circuit, grounded windings or burn

out. Compressor may be seized;

check refrigerant. If necessary, replace

compressor.

High or low pressure switch open or

defective.

If manual reset (high pressure), reset

switch. (Switch opens at 600 psi and will

not reset above 420 psi for R-410A). If auto

reset (low pressure) does not reset and

everything else is okay, replace switch.

Open room thermostat or control (no

cooling required).

Check room temperature. If temperature is

proper, wait for thermostat to close.

Loose wiring. Check all wire terminals and tighten as

necessary.

Compressor starts

but cuts out on low

pressure.

Low pressure switch

activates at 50 psig

Low or loss of refrigerant charge. Check refrigerant pressures.

Airﬂow restricted.

Check for dirty evaporator coil, dirty ﬁlters,

dampers closed, iced evaporator coil,

improper belt, check motor amps, check

duct design.

Restriction in refrigerant line.

Check refrigerant pressure, check and

adjust thermal expansion valve. If not

functioning properly, check for pressure

drop across the ﬁlter-drier.

Always have a completed Pre Start-Up Checklist, Unit Start-Up Checklist and Optional Accessories Checklist

prior to requesting parts or service information.

NOTE: Unit is equipped with a phase loss/phase reversal control. If system does not start, check phase of

electrical supply.

The ﬁrst step in troubleshooting a refrigeration circuit is to examine the DDC and Digital Scroll

compressor controller (if present) and see if there is a fault code. The next step is to check airﬂow

conditions. (e.g. improper ductwork, atypical wet bulb / dry bulb, etc.) After these steps have been

eliminated, proceed with troubleshooting by following this guide:

Troubleshooting – Refrigeration Circuit (optional)

TROUBLESHOOTING NOTE

Before any components are changed on the

refrigeration system, the cause of the failure must be

determined. Further problems will exist unless the

true cause or problem is identified and corrected.

IMPORTANT

Do not release refrigerant to the atmosphere! If

required service procedures include the adding or

removing of refrigerant, the service technician must

comply with all federal, state and local laws. The

procedures discussed in this manual should only be

performed by a qualified EPA Certified Technician.

14 Packaged DX Module for Make-Up Air Unit

Troubleshooting – Refrigeration Circuit (continued)

Symptom Possible Cause Corrective Action

Compressor starts

but cuts out on high

pressure switch.

High pressure

activates at 600 psig

Refrigerant overcharge. Check pressures, charge by subcooling.

Condenser fan motor defective. Check fan motor.

Condenser coil inlet obstructed or dirty. Check coil and inlet clearances.

Air or non-condensables in system. Check high side equalized pressures,

check thermal expansion valves.

Defective high pressure switch. Replace.

Restriction in discharge or liquid line.

Check refrigerant line pressures, check

thermal expansion valves, replace any

defective component.

Condensing fan relay not pulling in. Replace.

Reheat valve and bypass valve not

opening. Check valves or valve circuit board.

Compressor cuts out

on thermal overload

Low voltage. Check voltage.

Sustained high discharge pressure.

Check running amperage and conditions

described under “low suction pressure”

symptoms.

High suction and discharge pressures.

Check thermal expansion valve setting,

check for air in system. Check air

conditions and cfm.

Defective compressor overload.

If compressor is hot, allow compressor

to cool for two hours. Recheck for open

circuit.

Improper refrigerant charge. Check subcooling.

Improperly wired. Review wiring schematics.

Loose wiring. Check all connections.

Defective start relay. Replace relay.

Motor windings damaged. Verify amp draw.

Compressor hums,

but will not start

Improperly wired. Review wiring schematics.

Low line voltage. Check voltage.

Loose wiring. Check all connections.

Defective start relay. Replace relay.

Motor winding damaged. Verify amp draws. Replace compressor if

necessary.

Internal compressor mechanical damage. Replace.

Compressor noisy or

vibrating

Refrigerant overcharge. Check pressures and subcooling.

Liquid ﬂoodback. Check thermal expansion valve setting.

Check for refrigerant overcharge.

Tubing rattle.

Dampen tubing vibration by taping or

clamping. Carefully bend tubing away from

contact where possible.

Scroll Compressor rotating in reverse

(3-phase). Rewire for opposite rotation.

Worn or damaged compressor. Replace the compressor.

Improper mounting on unit base. Check that compressor is properly

isolated.

Always have a completed Pre Start-Up Checklist, Unit Start-Up Checklist and Optional Accessories Checklist

prior to requesting parts or service information.

Packaged DX Module for Make-Up Air Unit

Symptom Possible Cause Corrective Action

High suction

pressure

Excessive load on evaporator coil. Check for high entering wet bulb

temperature, check for excessive air.

Compressor is unloaded (Digital Scroll). Check Digital Scroll controller signal and

solenoid valve.

Expansion valve sensing bulb not secured

to suction line.

Check the thermal expansion valve, ensure

bulb is insulated.

Check superheat. If superheat is high, then

valve is choking refrigerant ﬂow.

• Check bulb for contact.

• Adjust valve for superheat. ~10°F

• Replace valve power head or valve.

Thermostatic expansion valve pressure

limit feature incorrect or inoperative.

Overfeeding.

Check bulb location and clamping. Adjust

superheat. Replace expansion valve power

head.

Room load too large. Reduce the load or add more equipment.

Overcharged. Check pressures and subcooling.

High discharge

pressure

Thermal expansion valve setting. Check thermal expansion setting and

calibrate superheat / subcooling.

Air inlet to condenser dirty or obstructed. Check for proper clearances and possible

air recirculating.

Condenser fan motor defective. Check condenser fan motor.

Too much refrigerant. Remove excess refrigerant.

Non-condensable in system. Remove non-condensable from system.

Dirty condenser coil. Clean condenser coil.

Condenser fan not running or running

backwards.

Check electrical circuit and fuse. Check

fan cycling controls.

High load conditions. Add more equipment or reduce load.

Low suction

pressure

Refrigerant undercharge/loss of refrigerant

charge. Check pressures and subcooling.

Blower running backward. Interchange any two wires from 3 phase

disconnect.

Loose blower, pulley or belts. Check drive pulley alignment, belt tension.

Low entering air temperature (low load

conditions). Check entering air wet bulb conditions.

Refrigerant leak. Check system for leaks. Repair leaks and

add refrigerant.

Evaporator dirty or iced up or airﬂow

restricted.

Clean the coil. Check fan operation. Check

airﬂow.

Plugged liquid line ﬁlter-drier. Replace ﬁlter-drier, check psi across ﬁlter.

Improper Hot Gas Bypass setting. Check setting and correct as required.

Expansion valve defective, superheat too

high or valve too small.

Adjust valve for proper superheat or

replace the expansion valve if too small or

defective.

Moisture in system, check sight-glass. Reclaim refrigerant, check for leaks,

recharge.

Always have a completed Pre Start-Up Checklist, Unit Start-Up Checklist and Optional Accessories Checklist

prior to requesting parts or service information.

Troubleshooting – Refrigeration Circuit (continued)

16 Packaged DX Module for Make-Up Air Unit

Symptom Possible Cause Corrective Action

Low discharge

pressure

Insufﬁcient refrigerant charge. Check subcooling, check for leak. Repair

leak and add refrigerant.

Defective or improperly adjusted

expansion valve.

Check superheating and adjust thermal

expansion valve.

Low suction pressure. See “low suction pressure”.

Faulty condenser temperature controls.

(Condensing fan cycle switch).

Check condenser controls and reset to

obtain desired condensing temperature.

Compressor short

cycles

Thermostat location or controls

malfunction.

Check thermostat, check heat anticipator

setting.

Improper refrigerant charge. Check subcooling, verify superheat.

Defective high or low pressure control. Check high or low pressure switch.

Liquid ﬂoodback. Possible tight bearings, see above.

Defective expansion valve. Check thermal expansion valve and

superheat.

Poor air distribution. Check ductwork for recirculating.

High discharge pressure. See “high discharge pressure”.

Leaking discharge valves in compressor. See “high suction pressure”.

Low airﬂow at evaporator(s). Check blower operation and airstream

restrictions.

Incorrect unit selection (oversized). Contact factory.

Always have a completed Pre Start-Up Checklist, Unit Start-Up Checklist and Optional Accessories Checklist

prior to requesting parts or service information.

Packaged DX Module for Make-Up Air Unit

This unit requires minimal maintenance to operate

properly. To ensure proper operation and longevity,

the following maintenance schedule should be

followed. The items in this list assume a relatively

clean air environment, and may require attention more

frequently in a dusty or dirty area. If this unit contains

an indirect gas-ﬁred heater, refer to the Installation,

Operation and Maintenance manual provided with

the unit for maintenance purposes. An EPA Certiﬁed

Technician should complete all refrigeration systems

checks.

Maintenance Frequency:

Monthly

1. Condensate Drain

Inspect and clean. Reﬁll with water or glycol.

Annually

It is recommended that the annual inspection and

maintenance occur at the start of the cooling season.

After completing the checklist, follow the unit start-up

checklist provided in the manual to ensure the

refrigeration system operates in the intended manner.

1. Door Seal

Check if intact and pliable.

2. Wiring Connections

Check all connections for tightness.

3. Cabinet

Check entire cabinet, inside and out, for dirt

build-up or corrosion. Remove accumulated

dirt, remove any surface corrosion and coat

the area with appropriate ﬁnish.

4. Evaporator Coil Maintenance

Check for cleanliness. Clean if required.

5. Condenser Coil Maintenance

Check for cleanliness. Clean if required.

6. Condensate Drain

Inspect and clean. Reﬁll with water.

7. Condensing Fan Blades and Motors

Check for cleanliness.

Check all fasteners for tightness.

Check for fatigue, corrosion and wear.

DANGER

Electric shock hazard. Can cause injury or death.

Before attempting to perform any service or

maintenance, turn the electrical power to the unit

to OFF at disconnect switch(es). Unit may have

multiple power supplies.

CAUTION

Use caution when removing access panels or other

unit components, especially while standing on a

ladder or other potentially unsteady base. Access

panels and unit components can be heavy and

serious injury may occur.

Routine Maintenance Maintenance Procedures:

Lubrication

Check all moving components for proper lubrication.

Apply lubricant where required. Any components

showing excessive wear should be replaced to

maintain the integrity of the unit and ensure proper

operation.

Dampers

Check damper (if present) to ensure it opens and

closes properly and without binding. Apply power to

motorized dampers to ensure the actuator opens and

closes the damper as designed.