To Start Unit — Be sure that crankcase heater has been
on for 12 hours and that field disconnect is closed. Set room
thermostat below ambient temperature. Operate unit for
15 minutes, then check system refrigerant charge. See Re-
frigerant Charging section on page 10.
Unit compressor starts after a 5-minute delay if equipped
with accessory Time Guard® II device (part no. 38HD900021).
See separate accessory installation instructions to install this
accessory. When ambient temperature will fall below 55 F,
accessory low-ambient controller (part no. 38HD900001) is
required.
SERVICE
Before performing recommended maintenance, be sure
unit main power switch is turned off. Failure to do so
may result in electrical shock or injury from rotating fan
blade.
Outdoor Fan — Areinforced wire mount holds the outdoor-
fan motor assembly in position. See Fig. 8 for proper mount-
ing positions.
High-Pressure Relief Valve — Valve is located in
compressor. Relief valve opens at a pressure differential of
approximately 450 6 50 psig between suction (low side) and
discharge (high side) to allow pressure equalization.
Internal Current and Temperature Sensitive Over-
load —
Control resets automatically when internal com-
pressor motor temperature drops to a safe level (overloads
may require up to 45 minutes to reset). When an internal
overload is suspected of being open, check by using an ohm-
meter or continuity tester. If necessary, refer to Carrier Stand-
ard System Techniques Manual, Chapter 2, for complete
information.
Pumpdown Procedure — The system may be pumped
down in order to make repairs on low side without losing
complete refrigerant charge.
1. Attach pressure gage to suction service valve gage port.
2. Frontseat the liquid line valve.
The 38QR018C-060C unit coils hold only the factory-
designated amount of refrigerant. Additional refrigerant
may cause units to relieve pressure through compressor
internal pressure relief valve (indicated by a sudden rise
of suction pressure) before suction pressure reaches
5 psig. If this occurs, shut off unit immediately, front-
seat suction valve, and remove and reclaim excess re-
frigerant following accepted practices.
3. Start unit and run until suction pressure reaches 5 psig or
low-pressure switch opens.
4. Shut off unit and frontseat suction valve.
5. Depressurize low side of unit and reclaim refrigerant fol-
lowing accepted practices.
USED WITH UNITS 40AQ,
40QB/QH, FD3A, FB4A,
FB5A, FK4A, 40DQ AND
40YA/YR/YZ
USED WITH UNITS
FF1A AND 40RC
USED WITH UNITS
FF1A AND 40RC
USED WITH UNITS 40AQ, 40QB/
QH, FD3A, FB4A, FK4A, FB5A,
40DQ, AND 40YA/YR/YZ
NOTE: Remove factory-installed jumpers on indoor unit
terminal board when installing outdoor thermostats.
LEGEND
ODT — Outdoor Thermostat
SHR — Supplemental Heat Relay
Splice Connection
Factory Wiring
Field Wiring
Fig.7—Typical Control Circuit Connections
UNIT SIZE-in. (mm)
38QR018C 38QR024C,030C,036C 38QR048C,060C
.433 (11) .709 (18) .16 (4)
Fig. 8 — Outdoor Fan Mounting Positions
7
(68 pages)
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