Carrier Weathermaster 38HQ Dimensions and installation guide

Number One
ArConditbning
Maker
r^rrie^
Division of
^1^ Carrier Corporation
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Weathermaster III Dual-Compressor
Heat Pump
(Outdoor Coil Section; Indoor Compressor Section)
INDEX
Page
SAFETY CONSIDERATIONS .1
INSTALLATION.3
Step 1 — Check Equipment and Jobsite . 3
• UNPACKAGE UNITS
• INSPECT EQUIPMENT
• COMPLETE OR CONSIDER SYSTEM
REQUIREMENTS
Step 2 — install Outdoor Coil
Section.4
• ON THE GROUND
• ON THE ROOF
Step 3 — Install Indoor Compressor
Section.5
Step 4 — install Indoor Fan-Coil and
Electric Heater.5
Step 5 — Make Piping Connections.5
• REPLACE THE ACCURATER^^
REFRIGERANT CONTROL PISTON(S)
• CONNECT REFRIGERANT LINES
Step 6 — Install Fan Control Package ... 6
Page
Step 7 — Install Outdoor Ambient
Switch.6
Step 8 — Install Room Thermostat,
Outdoor Thermostat(s) and
Emergency Heat Relay. 8
Step 9 — Make Electrical Connections ... 8
• INSTALL A BRANCH CIRCUIT
DISCONNECT PER N.E.C.
• ROUTE LINE POWER LEADS INTO
COMPRESSOR SECTION
• CONNECT GROUND LEADS AND
POWER WIRES
• CONNECT POWER LEADS FROM
INDOOR COMPRESSOR SECTION
TO OUTDOOR COIL SECTION
• CONNECTCONTROL WIRING
INITIAL START-UP.9
SEQUENCE OF OPERATION. 9
SERVICE. 11
MAINTENANCE . 15
SAFETY CONSIDERATIONS
Installation and servicing of air conditioning
equipment can be hazardous due to system pressure
and electrical components. Only trained and quali¬
fied service personnel should install, repair or
service air conditioning equipment.
Untrained personnel can perform basic mainten¬
ance functions of cleaning coils and filters and re¬
placing filters. All other operations should be per¬
formed by trained service personnel. When working
on air conditioning equipment, observe precautions
in the literature, tags and labels attached to the unit
and other safety precautions that may apply.
Follow all safety codes. Wear safety glasses and
work gloves. Use quenching cloth for brazing opera¬
tions, Have fire extinguisher available for all brazing
operations.
WARNING: Before perforisaisag; servsoe or
oa tant: OSS'
ijsain SEWstchfes mdoor tnataad otJt^oor
axat ITarn accessory heater power if '
shod: cooSd cause per-
© Carrier Corporation 1979
Form 38HQ-6SI

A
VAPOR LINE CONN (ON SERVICE VALVE)
liquid line
CONN. (ON
SERVICE VALVE)
MTG SLOTS
(USE ANY 2)
VDIAM HOLE
FOR CONTROL
WIRING
DRAINAGE HOLES
WM SPACE RE(3UIRED FOR SERVICE ^AIRFLOW
Certified dimension drawings available on request
Fig. 1 — Dimensions and Connections, 38HQ
Outdoor Coil Section (Table 2)
Table 1 — Carrier-Approved 38HQ
Weathermaster III Dual-Compressor
Heat Pump Systems
INDOOR 1
COMPRESSOR 1
SECTION
OUTDOOR
COIL
SECTION
INDOOR
FAN/COIL
38HQ227
38HQ940
40FS160/28VQ036
38HQ234
38HQ960
40FS200/28VQ042
VAPOR LINE CONN TO
OUTDOOR COIL
VAPOR LINE CON
TO INDOOR COIL
14 DIAM HOLE
FOR COMPRESSOR
SECTION LINE POWER
yC&K;
38HQ
INDOOR
COMPRESSOR
SECTION
i DIAM HOLE
FOR OUTDOOR
COIL SECTION
LINE POWER WIRING
(SEE ELECTRICAL
DATA AND WIRING)
t DIAM HOLE FOR
CONTROL WIRING
Pill SPACE REQUIRED FOR SERVICE
Certified dimension drawings available on request
Fig. 2 — Dimensions and Connections, 38HQ
Indoor Compressor Section (Table 2)
Table 2 — Physical Data
INDOOR COMPR SECTION
38HQ227
38HQ234
Operating Wt (lbs)
205
225
Dimensions (ft-in.)
Width
A
2-2-3/32
Depth
B
1-4-3/16
Height
C
1-11-1/8 (add 3/4-in for
Refrigerant Fittings
Compressor
no. 1
IV1D2713GM
(46)
MD3413GIVI
(46)
(Oil Recharge, oz)
no. 2
MD3413GMi
(46)
MD3413GM
(46)
AccuRater Size (in.)
Indoor
no 6 ( 0670)
no 7(0760)
Outdoor
no 3 (.0550)*
no 5 ( 0635)
Refrig Conn (in.)
3/4
3/4
OUTDOOR COIL SECTION
38HQ940
38HQ960
Operating Wt (lb)
107 125
Dimensions (ft-in.)
Diameter
A
2-5-1/4
2-5-1/4
Unit Height
B
2- 8
3- 8
Coil Height C
1-11
2-11
Refrig Conn
Vapor (in., ODF)
3/4, Compatible Fitting
Liquid (in., ODF)
3/8, Flare Fitting
*Piston size shown is shipped with section Remove factory-
installed piston; replace with size shown per text
2

Table 3 — Heater Airflow Data
■ i
INDOOR
COMPRESSOR
SECTION
HEATER
MINIMUM ALLOWABLE
SIZE
Airflow (cfm) \
Fan Speed
38HQ227
8 thru 20 kw
(40FQ91 6010 thru 090)
1150 j Low
38HQ234
10 thru 25 kw
(40FQ920060 thru 1 50)
1550 Low
Table 4 — Accessories
PART NO.
38CQ900102
38CQ900122
38CQ900132
38CQ900152
38CQ900172
38HQ900011
38HQ900002
38RQ900012
38CQ900072
38RQ900072
DESCRIPTION
Six 38CQ900081 Low-voltage Honeywell Thermostat (HH07AT071) and Thermostat Subbase (HH93AZ073)
with automatic changeover
Six 38CQ900111 Low-voltage Honeywell Thermostat (HH07AT071) and Thermostat Subbase (HH93AZ075)
with manual changeover
Six 38CQ900091 Liquid Line Filter-Drier
Six 38CQ900141 Solid State Time Guard (24 v)
SixHH22AG110 Optimizer Control
Hot Shot Heat Reclaim Device
Six 38 H Q900001 Outdoor Thermostat
Six 38RQ900001 Emergency Heat Relay
Six 38CQ900061 two-packs. Flare (3/8-in ) to compatible (3/8-in ) couplings
Six 38RQ900061 Heat Pump Stand for Outdoor Coil Section
TUBING
PACKAGE
TUBING
Length
(ft)
Liquid
Suction*
COMPR
SECTION
O.D
(in.)
Tube End
0 D (in )
0 D.
(in.)
Tube End
O D. (in )
Evap
Cond
38GC900071
10
3/8 3/8
3/4 3/4
3/4
38GC900081
18
3/8 3/8
3/4 3/4
3/4
38GC900091
25
3/8 3/8
3/4 3/4
3/4
38HQ227
38GC900101
35
3/8 3/8
3/4
3/4
3/4
38GC900111
50
3/8
3/8
3/4
3/4
3/4
1-1/8 in OD Suction Tube, Field Supplied
38HQ234
‘Suction line is insulated and has a 90° bend at one end
INSTALLATION
Step 1 — Check Equipment and Jobsite
UNPACKAGE UNITS — Move units to final loca¬
tion. Slide units from cartons taking special care
not to damage service valves, compatible fittings
or grilles. Check unit model numbers. Use only
Carrier-approved unit combinations in system. See
Table I.
INSPECT EQUIPMENT — File claim with ship¬
ping company if shipment is damaged or incomplete.
COMPLETE OR CONSIDER SYSTEM RE¬
QUIREMENTS before installing the 38HQ units.
Consult local building codes and National Elec¬
trical Code (NEC) for special installation
requirements.
When installing units, allow sufficient space for
airflow clearance (outdoor unit), wiring, refrigerant
piping and servicing unit. Position outdoor unit so
water or ice from roof cannot drop directly on top
of unit. Maximum allowable vertical distance be¬
tween indoor and outdoor sections is 50 feet. It is
strongly recommended that 38HQ units be used
with only Carrier-approved indoor sections (see
Table 1).
Outdoor Coil Section — Make provision for con¬
densate drainage and defrost water disposal whether
unit is installed on ground, roof or off-the-wall
platform. Outdoor unit must be elevated 12 in. to
18 in. in areas of heavy snowfall. (Ensure unit base-
pan drainage holes are not blocked. See Fig. 1.) See
Step 2, Install Outdoor Coil Section for details.
Roof installation method for 38HQ depends on
building construction and special requirements of
local codes. Make sure roof can support unit weight.
Indoor Compressor Section — Locate unit in base¬
ment, garage or utility room. Indoor locations with¬
in the living space are not recommended. Basement
installations also require careful planning to avoid
areas directly under bedrooms, living rooms, etc.
3

Insert felt isolation pad (factory supplied) be¬
tween unit and a level rigid mounting base to absorb
vibration. Isolate interconnecting tubing from
framing and ductwork or where tubing runs thru
stud spaces, enclosed ceilings or pipe chases. Use
isolation type hanger, Fig. 3, since rigid fastening
will transmit pulsation to structure creating ob¬
jectionable sound.
System Refrigerant Control consists of factory-
installed byp^s-type AccuRateF” devices located
as shown in Fig. 15. These metering devices include a
replaceable orifice piston that is calibrated to
regulate refrigerant flow. Piston data is given in
Table 2. In some instances, the factory-installed
piston must be replaced by a factory-supplied re¬
placement piston. Where required, substitute
pistons as described in Step 5 and as indicated on
tags attached to system AccuRater devices.
Step 2 — Install Outdoor Coil Section
ON THE GROUND — Use a solid, level concrete
pad as shown in Fig. 4. Position unit so that coil
drainage holes in basepan overhang the pad. (See
Fig. 1 for drainage hole locations.) Be sure pad does
not obstruct drainage holes (water drains from holes
during heating and defrost cycles). Attach unit to
pad with 1 / 4-in. mounting bolts. Any 2 holes in unit
basepan may be used to fasten unit to pad.
Construct round, 24-in. diameter 6-in. thick pad a
minimum of 6 in. above grade to provide clearance
under holes for drainage and ice build-up. In areas
where prolonged subfreezing temperatures or snows
occur; increase clearance by using accessory heat
pump stand to support unit 12 to 18 in. off concrete
base. See Fig. 4. Be sure stand does not obstruct coil
drainage holes. Avoid mounting unit in prevailing
Winds to minimize effect on defrost performance.
Construct wind break if necessary. Extend a 12-in.
gravel apron around pad for condensate and defrost
water drainage field.
Provide support bracket from structure or other
solid support to outdoor unit to give stability. Since
it is lightweight, the outdoor section may be
Fig. 4 — Unit Support Details
mounted on a platform attached to or built out from
structure. Construct platform using drainage and
clearance recommendations above. Locate and con¬
struct platform to avoid possible transfer of unit
vibration to structure. See Table 2 for unit weight.
ON THE ROOF: Install a level platform or frame to
support unit. Elevate unit for proper clearance as
previously described for on-the-ground installation.
Plan roof design and water drainage to prevent unit
from sitting in water. Flash all roof openings to
prevent leaks.
4

Step 3 — Install Indoor Compressor Section on
a level, rigid, solid platform or concrete floor. Do
not install in a living area.
Insert 1/4-in. asphalt-impregnated felt pad
(supplied) between unit basepan and mounting
surface to provide full unit support and vibration
attenuation. (Do not use vibration isolators under
corners of basepan.)
Step 4 install Indoor Fan-Coil and Electric
Heater as described in Installation Instructions
supplied with this equipment. Install and connect
thermostats and other controls as described in the
steps that follow.
Step 5 — Make Piping Connections — The
38HQ sections may be connected to indoor fan-coil
using Carrier accessory tubing packages or field-
supplied tubing of refrigerant grade. See Table 2 for
unit piping connection types, sizes and line size
recommendations and Table 4 for accessory tubing
sizes. Maximum allowable system liquid line length
is 100 feet. Maximum vapor line length from com¬
pressor section to indoor coil is 50 feet. Maximum
vapor line length from compressor section to out¬
door coil is 50 feet.
When other than 25 ft of interconnecting piping
! is used, follow special requirements described in
^ Refrigerant Charging. Do not use less than 10 ft of
vapor or liquid line.
Do not use damaged or contaminated tubing.
Always evacuate or purge indoor coil, compressor
section and tubing system. When purging, use field-
supplied refrigerant, not unit refrigerant.
When making tubing connections, be sure to
provide clearance at unit for electrical connections.
Follow tubing isolation recommendations described
previously.
REPLACE THE ACCURATER"” REFRIG¬
ERANT CONTROL PISTON(S) before connect¬
ing refrigerant lines as applicable. Refer to tags
attached to AccuRater device. Replacement pistons
are shipped with compressor section and are to be
installed as directed on tag. Replacement procedure,
briefly described below, is detailed on tag. Also, see
AccuRater Servicing for additional information.
When connecting indoor compressor section
38HQ227 to outdoor coil section 38HQ940, remove
no. 4 piston from outdoor coil AccuRater device;
replace with no. 3 piston. Attach AccuRater identi¬
fication sticker to unit (replacing existing sticker, if
any).
CONNECT REFRIGERANT LINES to fittings on
indoor and outdoor sections. Fig. 1, 2 and 5. Indoor
compressor section has 2 Compatible Fitting vapor
line connections. Outdoor and indoor fan-coil
sections have Compatible Fitting vapor line connec¬
tion and liquid line flare connection.
Flare and connect liquid line from outdoor coil
section to indoor fan-coil unit. It is not necessary
to flare system liquid line if an accessory flare-to-
Fig. 5 — Refrigerant Piping Connections
5

Compatible Fitting coupler is used for liquid line
connection. See accessory coupler, Fig. 6.
Connect vapor line from outdoor coil section to
indoor compressor section, and from compressor
section to indoor fan-coil. Section vapor line as
required (Fig. 5). Use correct compressor section
vapor line connection to indoor and outdoor coils.
Unit Compatible Fittings permit mechanical or
sweat connection as described below.
When a 1-1/8 in. field-supplied vapor line is used
on 38HQ234, four field-supplied 3/4-in. to 1-1/8 in.
vapor line adapters must be provided.
Insulate Refrigerant Lines — After making tubing
connections, the compressor section fittings must be
insulated. Butt the Armaflex tubing insulation (pro¬
vided in tubing package) against the Compatible
Fittings. Secure the insulation with Prestite or an
equivalent material which provides both adhesion
and insulation. Also wrap the Compatible Fittings
with Prestite to prevent sweating.
Mechanical Connection-to-Compatible Fitting
(Mate one set of connections at a time.)
1. Loosen nut on Compatible Fitting one turn. Do
not remove.
2. Remove plug and be sure 0-ring is in the groove
inside the Compatible Fitting.
3. Cut tubing to correct length.
4. Insert tube into Compatible Fitting until it
bottoms.
5. Tighten nut until it bottoms on back coupler
flange. Keep tube bottomed in Compatible
Fitting while tightening nut.
Sweat Connection-to-Compatible Fitting (Use
refrigerant grade tubing.)
1. Remove locking nut, rubber O-ring and Schrader
core from valve.
2. Cut tubing to correct length.
3. Insert tube into Compatible Fitting. Wrap top
and bottom of service valves in wet cloth to pre¬
vent damage by heat. Solder with low tempera¬
ture (430 F) silver alloy solder.
4. Replace Schrader core.
5. Evacuate or purge system with field-supplied
refrigerant.
Accessory Flare-to-Compatible Fitting Coupler is
shown in Fig. 6. Attach flare nut on coupler to flare
fitting on unit liquid line connection. Connect liquid
line to Compatible Fitting using mechanical or
sweat connection. When mechanical connection is
made, use 2 wrenches to tighten Compatible Fitting
nut — one to hold coupler and one to tighten nut.
Fig. 6 — Accessory Coupler
Step 6 — Install Fan Control Package (factory
supplied; packaged separately inside indoor com¬
pressor section) — This control, consisting of a
transformer and a relay, provides high-speed fan
operation when both compressors are energized.
Refer to connection diagram in Fig. 7 for wiring
details. Install control as follows:
1. Remove factory-installed transformer from
indoor fan-coil unit electric heater package.
Refer to 40FS service instructions as required.
2. Install fan control package in upper right-hand
corner of the 40FS.
3. Route wires from controls to heater package thru
knockouts provided. Restore transformer wiring
connections including ground wire.
4. Connect black wire from indoor fan relay (IFR)
terminal no. 4 (or no. 6) to black wire from
indoor fan relay no. 2 (IFR-2) terminal no. 3.
(Cut off male connector from IFR wire; supply
wire nut to splice wires.)
5. Connect black wire from IFR-2 terminal no. 6 to
fan speed selector block terminal no. 1 (high
speed).
6. Connect blue wire from IFR-2 terminal no. 1 to
fan speed selector block terminal no. 3 (low
speed).
7. Connect low-voltage field control wires between
indoor compressor section and indoor fan relay
(IFR-2) orange pigtails (TB OA to OFR-2, ter¬
minal no. 4; contactor C-2, terminal C to IFR-2,
terminal no. 5). Field-supplied, 24-gage, NEC
Class 2 thermostat wire may be used.
Step 7 — Install Outdoor Ambient Switch
(OA) (factory-supplied; packaged separately inside
indoor compressor section) — This switch activates
compressor no. 2 when the first heating thermal
balance point is reached. The switch is installed in
the same manner as the outdoor thermostat (step 8),
except refer to Fig. 7 for correct wiring.

FAN CONTROL PACKAGE
LEGEND
C-2 — Contactor
IFR — Indoor Fan Relay
PL — Plug, Fan
SEQ — Sequencer
TB — Terminal Board
Tran — Transformer
# Junction
o Component Connection (Marked)
Field Splice
HiW Field Power Wiring
Field Ground Wiring
_Field Control Wiring
NOTES:
1 Use copper conductors only.
2 May be terminal board or fuse block depending
on heater model used
3 Will be terminal no 4 on 40FQ916 models,
and terminal no 6 on 40FQ920 models
THERMOSTAT 40FQ
SUBBASE ELECTRIC HEATER
HH93AZ073 0R TERMINAL
HH93AZ075 BOARD
38HQ
COMPRESSOR
SECTION
TERMINAL BOARD
THERMOSTAT 40FQ
SUBBASE ELECTRIC HEATER
HH93AZ0730R TERMINAL
HH93AZ075 BOARD
38HQ
COMPRESSOR
SECTION
TERMINAL BOARD
(38HQ WITH 40FS/28HQ,VQ
EQUIPPED WITH ELECTRIC HEATER;
EMERGENCY HEAT, ONE OUTDOOR THERMOSTAT)
THERMOSTAT
SUBBASE
HH93AZ073 OR
HH93AZ075
40FQ
ELECTRIC HEATER
TERMINAL
BOARD
38HQ
COMPRESSOR
SECTION
TERMINAL BOARD
COOLING AND TWO-STAGE HEATING
(38HQ WITH 40FS/28HQ,VQ
EQUIPPED WITH ELECTRIC HEATER;
EMERGENCY HEAT, NO OUTDOOR THERMOSTATS)
THERMOSTAT 40FQ 38HQ
SUBBASE ELECTRIC HEATER COMPRESSOR
HH93AZ0730R TERMINAL SECTION
HH93AZ075 BOARD TERMINAL BOARD
EQUIPPED WITH ELECTRIC HEATER;
EMERGENCY HEAT, TWO OUTDOOR THERMOSTATS)
DFT — Defrost Thermostat
EHR — Emergency Heat Relay
OA — Outdoor Ambient Switch
ODT — Outdoor Thermostat
_ Factory Wiring
_Field Wiring
^Transformer (75 va) located in fan control package
tTerminal L is identified as terminal X on some former thermostats (Required for system
malfunction warning indicator on compressor section )
^Remove 1 or both factory-installed jumpers (connection B) when installing outdoor ther¬
mostats (ODT) shown in connections C and D
Fig. 7 — Control Circuit Connections
7

Attach one lead to compressor terminal board
connection OA. Connect other lead to line side of
defrost thermostat.
Set switch at temperature of first thermal balance
point (heating). This balance point is provided by
CLIC load estimating program. Further adjust¬
ments can be made following operating experience.
Step 8 — Install Room Thermostat, Outdoor
Thermostat(s) and Emergency Heat Relay —
Follow Installation Instructions shipped with these
accessories plus the instructions in the sections that
follow. Connect as described in step 9.
INDOOR THERMOSTAT — Use only Carrier
indoor thermostat and subbase as shown in Table 4.
Set heat anticipator settings according to Table 5.
These settings may be changed slightly to provide
a greater degree of comfort for certain installations.
Table 5 — Thermostat Heat Anticipator
Settings
INDOOR
COM PR
SECTION
OUTDOOR
COIL
SECTION
INDOOR
UNIT WITH
ELECTRIC
HTR
HTR
KW
ANTICIPATOR
SETTINGS
First
Stage
Second
Stage
38HQ227
38HQ940
40FS160 with
40FQ916010
thru 090
8 thru
20
Fixed 16
38HQ234
38HQ960
40FS200 with
40FQ920060
thru 150
10 thru
25
Fixed 49
OUTDOOR THERMOSTAT ACCESSORY pro¬
vides adjustable outdoor control of accessory
electric heater (used on indoor fan-coil). This ther¬
mostat closes on a drop in outdoor temperature.
It energizes a stage of electric heat when the out¬
door temperature setting is reached, provided the
room thermostat is on the second stage of heating.
One outdoor thermostat is recommended for each
stage of electric heat after the first stage. Connect
as described in Step 9. Set the outdoor thermostats
progressively lower for each stage. Refer to heat
load of building and unit capacity to determine the
correct outdoor thermostat settings. Locate maxi¬
mum of 2 outdoor thermostats in control voltage
section of outdoor coil section junction box. Fasten
in place with sheet metal screws.
EMERGENCY HEAT RELAY — This accessory is
required when 2 or more outdoor thermostats are
used. It is automatically energized by the manually-
operated emergency heat switch in the indoor ther¬
mostat subbase. The indoor thermostat locks out
the compressor and the relay bypasses the outdoor
thermostats for electric heater operation during heat
pump shutdown. When one outdoor thermostat is
used, an emergency heat relay is not required. The
emergency heat switch in the indoor thermostat
subbase bypasses the outdoor thermostat, locks out
the compressor and activates the electric heater.
Install emergency heat relay in a convenient loca¬
tion on indoor unit. Attach with sheet metal screw.
Connect relay as shown in Fig, 7.
Step 9 — Make Electrical Connections — In¬
stall field wiring in accordance with local and
national fire, safety and electrical codes. Be sure
voltage to units is within ± 10% of voltage indi¬
cated on nameplate. Contact local power company
for correction of improper line voltage.
When making electrical connections, provide
clearance at unit for refrigerant piping connections.
See Table 6 for recommended wire and fuse sizes.
Line power connections and control circuit connec¬
tions are shown in Fig. 7 and 8.
Route line and control power wiring for 38HQ
outdoor coil from connections in the 38HQ in¬
door compressor section. Use 14-ga (minimum) line
power wire size to outdoor coil section when total
wire length connecting compressor section to coil is
under 25 feet. If over 25 ft, use same wire size as
compressor section branch circuit.
Table 6 — Electrical Data
INDOOR
COMPR
SECTION
OUTDOOR
COIL
SECTION
VOLTAGE
COMPR
1
COMPR
2
OFM
(FLA)
BRANCH CIRCUIT
- n
Nom
1-Ph
60-Hz
1
1
1 Operating*
Power Wire ]
Gnd Wire
Sizet
(AWG)
Min
Ckt
Amps
Max
Fuse
Amps**
_
Min Size
(AWG)
Max Ft
1
Max Min
LRA
RLA LRA RLA
ICS OCS
ICS
OCS
ICS
OCS
38 H0227 38HQ940
230
254
207
72 17 88 1 17 8
1 5 6
14t
55
25t
10
14t
40 8
38HQ234 38HQ960 230
254 207 88
20
94 S
__ 1
21 2
2 3 4
14t
75
25t
10 14t
48 8
60
FLA — Full Load Amps
ICS — Indoor Compressor Section
LRA — Locked Rotor Amps
OCS — Outdoor Coil Section
OFM — Outdoor Fan Motor
RLA — Rated Load Amps
^Permissible limits of the voltage range (for limited period of time)
at which the units will operate satisfactorily
fOutdoor coil section wiring — for 25 ft wire run or less, use
minimum 14 AWG size wire For longer wire run use same size
as supply to compressor section
^Required when using nonmetallic conduit
**Maximum dual element fuse size
NOTES;
1 All units have 24-v control circuit which requires external
power source
2 Copper wire size table based on 60 C Use copper or copper-clad
aluminum wire to indoor section; copper wire only to outdoor
section Use latest National Electrical Code for wire sizing
8

FACTORY WIRING
Fig. 8 — Line Power Connections
INSTALL A BRANCH CIRCUIT DISCONNECT
PER N.E.C. of adequate size to handle compressor
section starting current. Provide a separate dis¬
connect switch for outdoor coil section. Provide a
separate disconnect for indoor fan-coil and for each
accessory electric heater circuit as required, (See In¬
door Unit and Electric Heater Installation, Start-Up
and Service Instructions.) Locate disconnect(s)
within sight of and readily accessible to the units, per
section 440-14 of National Electrical Code (NEC).
ROUTE LINE POWER LEADS INTO COM¬
PRESSOR SECTION — Extend lead from discon¬
nect per N.E.C. thru 1-1/8 in. hole provided in com¬
pressor section top panel (Fig. 2) and into control
box. Extend line power leads for outdoor coil
section thru 7/8-in. hole provided in compressor
section top panel and into control box.
CONNECT GROUND LEADS AND POWER
WIRES — Connect ground leads to the ground lug
in control box for safety. Splice compressor section
line power leads to yellow and black pigtails, and
outdoor coil section power leads to brown and blue
pigtails. Use wire nuts and tape at each splice con¬
nection as shown in Fig. 8.
CONNECT POWER LEADS FROM INDOOR
COMPRESSOR SECTION TO OUTDOOR
COIL SECTION thru secondary disconnect switch.
From this disconnect switch extend leads thru
hole provided in outdoor coil section basepan
(Fig. 1) and into line voltage section of junction
box. Fig. 14. Splice leads to black and blue pigtails
with wire nuts.
CONNECT CONTROL WIRING (24-v) — Extend
wiring thru 7 / 8-in. grommeted hole in compressor
section top panel (Fig. 2), and to control wiring
terminal board on side of control box. Connect
leads to terminal board as shown in Fig. 7. Extend
and connect control wiring from compressor section
to outdoor coil section as required. Make splice
connections in low-voltage section of coil junction
box.
Use indoor fan-coil transformer as 24-v supply for
system. Be sure fan control package is installed as
described in Step 6. Package contains 75-va trans¬
former of adequate capacity to handle system
current.
INITIAL START-UP
The compressors in the indoor compressor
section are equipped with crankcase heaters. It is
recommended that the heaters be energized a
minimum of 24 hours before starting the system. To
energize crankcase heaters only, set the thermostat
at OFF position and turn on main power to
compressor section.
To Start System — (Be sure crankcase heaters
have been energized for 24 hours.) Adjust the ther¬
mostat as follows:
1. Set selector switch at OFF.
2. Turn on main disconnect switch(es) to indoor
and outdoor units.
3. Set fan switch as desired (ON or AUTO.).
4. Set thermostat dial at desired temperature.
5. Set selector switch at HEAT or COOL.
Check system refrigerant charge. See Service —
Refrigerant Charging.
SEQUENCE OF OPERATION
Fan Switch at AUTO. Position, Thermostat at
ON Position (Crankcase heater is on as soon as the
field power supply is on.)
THERMOSTAT CALLS FOR COOLING
1. First-stage cooling thermostat (Co) closes and
the reversing valve solenoid (RVS) is energized.
The RVS actuates the reversing valve and
switches the system to cooling.
2. Second-stage cooling thermostat (Cl) closes. If
the low-pressure switch (LPS) is closed, com¬
pressor contactor (C) is energized and compres-
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sor no. 1 starts. At the same time, the outdoor fan
motor (OFM) starts and the defrost timer (DT) is
energized although it is not functional in the
cooling mode; the indoor fan relay (IFR) is
energized and the indoor fan motor (IFM) starts.
Compressor no. 2 does not run in COOL mode.
When the second stage of cooling is satisfied, Cl
opens. The compressor stops; the indoor and out¬
door fans stop; DT is de-energized. When the con¬
trolled temperature drops approximately 1 F below
the cooling set point, Co opens. RVS is de-energized
and the reversing valve switches to heating (normal
position). The unit is shut down except for the two
compressor crankcase heaters, which remain on as
long as the field power supply is on.
THERMOSTAT CALLS FOR HEATING (The
reversing valve is de-energized, in heating position.)
1. First stage heating thermostat (HI) closes. Com¬
pressor contactor no. 1 (Cl) is energized and
compressor starts; outdoor fan motor (OFM)
starts; defrost timer (DT) is energized. Indoor
fan relay (IFR) is energized and indoor fan
motor (IFM) starts. When the outdoor ambient
switch (OA) closes (at first thermal balance
point), compressor contactor no. 2 (C2) is ener¬
gized and compressor no. 2 starts. Compressor
no. 1 and compressor no. 2 operate simul¬
taneously as long as OA is closed. The crankcase
heaters are de-energized when both compressors
are running.
2. Second-stage heating thermostat (H2) closes and
activates the first accessory heater element
sequencer thru indoor thermostat terminal W2.
The first-stage electric heater element is energized
immediately and the other heater elements are
energized at regular intervals thru the sequencers.
Separate outdoor thermostats may be used to
energize the second sequencer and bring on addi¬
tional heater elements if more incremental heat
control is desired.
When the second stage of heating is satisfied, H2
opens and the electric heater(s) shuts off. When the
first stage of heating is satisfied, HI opens and the
unit shuts down, except for the compressor crank¬
case heater, which remains on as long as the field
power supply is on.
Unit Controls and Safety Devices
HIGH-PRESSURE RELIEF VALVE is located in
compressor. Relief valve opens at a pressure
differential of approximately 500 psi between
suction (low side) and discharge (high side) to allow
pressure equalization.
INTERNAL CURRENT AND TEMPERATURE
SENSITIVE OVERLOAD resets automatically
when internal compressor motor temperature drops
to a safe level (overloads may require up to 45 min¬
utes to reset). When an internal overload is suspected
of being open, check by using an ohmmeter or con¬
tinuity tester. If necessary, refer to Carrier Standard
Service Techniques Manual, Chapter 2, Electrical,
for complete instructions.
LOW-PRESSURE SWITCH is located in compres¬
sor section on suction line between reversing valve
and accumulator. Provides loss-of-charge protec¬
tion by shutting compressor off if suction pressure
drops below setting. Low-pressure switch settings
are: open, 5 ± 3 psig; close, 20 ± 5 psig.
CRANKCASE HEATERS are activated by a relay.
Heaters derive power from contactor no. 2 and are
energized when compressors are off or when only
one compressor is functioning.
The heater keeps the crankcase warm during the
off cycle and thus prevents dilution of the oil with
the refrigerant, assures good lubrication, and pre¬
vents loss of oil from crankcase during start-up.
If the electrical disconnect switch to the compres¬
sor section has been off for an extended period of
time, the crankcase heater should be energized for 24
hours before starting the compressor.
SIGNAL-LOC ™ SYSTEM MALFUNCTION
WARNING INDICATOR AND LOCKOUT ^
Indoor compressor section is equipped with a solid-
state warning logic circuit that protects the system.
In case of a malfunction (compressors do not oper¬
ate due to safety device cutout), emergency heat light
on thermostat comes on and compressors are pre¬
vented from restarting. Compressors can be re¬
started after resetting thermostat (turn thermostat
off then on). If either compressor malfunctions,
both will be locked out (prevented from restarting).
The emergency heat light goes out when com¬
pressors are restarted or when indoor thermostat is
satisfied. If the light does not stay out after two or
three attempts to restart, check for cause of
malfunction.
DEFROST CONTROL, consisting of a defrost
timer, defrost thermostat and defrost relay, inter¬
rupts normal system heating operation every 90
minutes to defrost outdoor coil, if the coil saturated
suction temperature indicates freezing tempera¬
tures. Defrost control simultaneously stops outdoor
fan, energizes reversing valve solenoid to return
system to cooling cycle (outdoor coil as condenser,
indoor fan-coil unit as evaporator), and activates
accessory electric heater.
For the heat pump to defrost, 2 conditions are
necessary;
1. Defrost timer contacts must be closed.
2. Refrigerant temperature from outdoor unit must
be cold enough to cause defrost thermostat
contacts to close. Contacts close at 27 (± 4) F.
Every 90 minutes of elapsed running time, the de¬
frost timer contacts close for 10 seconds. If the
defrost thermostat contacts are closed, the unit
defrosts. The defrost timer limits defrosting period
to 10 minutes. Normally the frost is removed and the
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