Step 7 − Install Remote Thermostat; Step 8 - Make Connections Between Indoor And Outdoor Units; Heat Pump Systems - Carrier 40QA Installation, Start-Up And Service Instructions Manual

Step 7 — Install Remote Thermostat —
unit is equipped with a remote thermostat which operates
the system. The thermostat monitors the system operation
and controls the operating mode. To change settings or modes
of operation, use the thermostat (see Fig. 19).
Mount thermostat to a wall in the occupied space using
2 field-supplied screws. Locate the thermostat in an area which
is not subjected to drafts or direct sunlight through
windows. Locate thermostat on an interior wall whenever
possible.
Step 8 — Make Connections Between Indoor
and Outdoor Units —
TB — Terminal Block
Fig. 17 — Line Power Connections
ASM — Air Sweep Motor
ASR — Air Sweep Relay
EQUIP GND — Equipment Ground
FL — Fuse Link
FPT — Freeze Protection Thermostat
HP — Heat Pump
HR — Heater Relay
HTR — Heater
HTT — Heater Temp. Thermostat
IFM — Indoor-Fan Motor
NOTES:
1. If any of the original wire furnished must be replaced, it must be
replaced with type 90 C wire or its equivalent.
2. Wire in accordance with NEC and local codes.
The 40QA
The thermostat is wired
NEC — National Electrical Code
PCB — Printed Circuit Board
PL — Plug
TB — Terminal Board
TRAN — Transformer
Terminal (Marked)
Terminal (Unmarked)
Splice
Fig. 18 — Control Circuit Connections Arrangement
between the indoor and outdoor units to make the system
complete.
Wire thermostat to fan coil unit according to Fig. 20 (cooling-
only systems or condensing units matched with heat pump
fan coil units) or Fig. 21 (heat pump only systems). Refer to
Cooling-Only Systems and Heat Pumps Systems sections be-
low to wire thermostat from fan coil unit to outdoor unit.
COOLING ONLY SYSTEMS — The following connec-
tions must be made to the 38HDC or HDS unit for it to op-
erate as a system with the indoor unit:
Route 2 wires of field-supplied 18-gage AWG (American
Wire Gage) thermostat cable between the low-voltage ter-
minal block of the fan coil unit and the 38HDC unit low-
voltage terminal block. Connect the wires Y1 to Y and C to
C. See Fig. 20.
HEAT PUMP SYSTEMS — The following connections must
be made to the 38QRC unit for it to operate as a system with
the indoor unit:
Route 6 wires of field-supplied 18-gage AWG thermostat
cable between the low-voltage terminal block of the fan coil
and the 38QRC unit low-voltage terminal block. Connect Y1
to Y, R to R, O to O, G1 to G, W2 to W2, and C to C with
the wires. See Fig. 21.
The 38QRC heat pump unit uses a timed defrost method.
The timed defrost can be field set for 30, 50, or 90 minutes.
The timed defrost is factory set for 90 minutes.
3. Transformer is thermally protected and will reset automatically.
4. Indoor-fan motor(s) are inherently thermally protected.
12
Terminal Block
Factory Wiring
Field Power Wiring
Field Control Wiring
Printed Circuit Board
Accessory or Optional Wiring