Carrier 38AQS012 - Service

18
Restart —
Manual reset of the 24-v control circuit is nec-
essary if unit shutdown is caused by automatic reset devices
(including IP [internal compressor overcurrent protection],
HPS [high-pressure switch], and LCS [loss-of-charge switch])
or if shutdown is caused by manual reset devices (including
OPS [oil pressure switch] and compressor circuit breaker pro-
tection). To restart the unit when IP, HPS, or LCS has tripped
(after device has reset automatically), open and then close the
thermostat contacts. Opening and then closing thermostat con-
tacts interrupts and restores 24-v power to the compressor lock-
out (CLO), which resets the circuit.
It is necessary to manually reset the compressor circuit
breaker and OPS at the unit if either of these safeties should
shut down the unit.
Causes of Complete Unit Shutdown:
• interruption of supplied power
• open compressor overtemperature protection (IP)
• compressor electrical overload protection (CB)
• open high-pressure or loss-of-charge safety switches
• open oil pressure switch
• open crankcase heater lockout (CLO2)
• open control circuit fuse (FU1 or FU2)
SERVICE
Compressor Removal —
See Tables 1A and 1B for
compressor information and Fig. 2 for component location.
Follow safety codes and wear safety glasses and work gloves.
1. Shut off power to unit. Remove unit access panel (front of
unit).
2. Recover refrigerant from system using refrigerant recovery
methods described in Carrier Training booklet GTAC II,
Module 5, and in accordance with local and national
standards.
3. Disconnect compressor wiring at compressor terminal
box.
4. Remove bolts from suction and discharge service valves.
5. Remove 2 bolts and 2 screws from compressor mounting
plate.
6. Remove crankcase heater from compressor base.
7. Remove compressor from unit.
8. Remove compressor holddown bolts and lift compressor
off mounting plate.
9. Clean system. Add new liquid line filter drier.
10. Install new compressor on compressor mounting plate
and position in unit. Connect suction and discharge lines
to compressor. Secure mounting plate with compressor to
unit. Ensure that compressor holddown bolts are in place.
Connect wiring. Install crankcase heater.
11. Evacuate and recharge unit.
12. Restore unit power.
Crankcase Heater —
The crankcase heater prevents re-
frigerant migration and compressor oil dilution during shut-
down when compressor is not operating.
Close both compressor service valves when crankcase heat-
er is deenergized for more than 6 hours.
Outdoor Unit Fans —
Each fan is supported by a
formed-wire mount bolted to the fan deck and covered with a
wire guard. The exposed end of the motor shaft is covered with
a rubber boot. In case a fan motor must be repaired or replaced,
be sure the rubber boot is put back on when the fan is rein-
stalled and be sure the fan guard is in place before starting the
unit. Figure14 shows the proper position of the mounted fan.
Lubrication
FAN MOTORS have permanently sealed bearings. No further
lubrication is required.
COMPRESSOR has its own oil supply. Loss of oil due to a
leak in the system should be the only reason for adding oil after
the system has been in operation. See Start-Up, Preliminary
Oil Charge.
Coil Cleaning and Maintenance —
This section dis-
cusses the cleaning and the maintenance of standard coils and
E-Coated coils. Routine cleaning of coil surfaces is essential to
minimize contamination build-up and remove harmful residue.
Inspect coils monthly and clean as required.
CLEANING STANDARD COILS — Standard coils can be
cleaned with a vacuum cleaner, washed out with low velocity
water, blown out with compressed air, or brushed (do not use
wire brush). Fan motors are dripproof but not waterproof. Do
not use acid cleaners.
Clean coil annually or as required by location or outdoor air
conditions. Inspect coil monthly and clean as required. Fins are
not continuous through coil sections. Dirt and debris may pass
through first section, become trapped between the 2 rows of
fins (38AQS012) or 3 rows of fins (38AQS016), and restrict
condenser airflow. Use a flashlight to determine if dirt or debris
has collected between coil sections.
Clean coils as follows:
1. Turn off unit power.
2. Remove screws holding rear corner posts and top cover
in place. Pivot top cover up 12 to 18 in. (300 to 450 mm)
and support with a board or other adequate rigid support.
See Fig. 15.
3. Remove clips securing tube sheets together at the return
bend end of the coil. Carefully spread the ends of the coil
rows apart by moving the outer sections. See Fig. 16.
4. Using a water hose or other suitable equipment, flush
down between the sections of coil to remove dirt and
debris.
5. Clean the remaining surfaces in the normal manner.
6. Reposition outer coil sections. Reinstall clips which se-
cure tube sheets, and replace top cover and rear corner
posts.
7. Restore unit power.
IMPORTANT: If OPS trips, it must be reset first before
making and breaking the thermostat contacts to reset
CLO. If this procedure is not followed, the CLO cannot
reset.
Excessive movement of copper lines at compressor may
cause higher levels of vibration when unit is restored to
service.
Fig. 14 — Outdoor Unit Fan