Carrier WEATHERMASTER 48/50Z030-105 - Manual (Page 132)

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EVAPORATOR-FAN MOTOR PROTECTION — A manu-
al reset, calibrated trip, magnetic circuit breaker protects
against overcurrent. Do not bypass connections or increase the
size of the breaker to correct trouble. Determine the cause and
correct it before resetting the breaker.
CONDENSER-FAN MOTOR PROTECTION — Each
condenser-fan motor is internally protected against over-
temperature. They are also protected against a severe over-
current condition by manual reset, calibrated trip, magnetic cir-
cuit breakers on a common circuit. As with the circuit breakers,
do not bypass connections or increase breaker size to correct
trouble. Determine the cause and correct it before resetting the
breaker.
HIGH-PRESSURE SWITCHES — See Fig. 51 for compres-
sor mounting locations. Settings for these switches are shown
in Tables 97A and 97B. If either switch trips, that refrigerant
circuit will be automatically locked out by the controls. To re-
set, recycle control power to unit.
Table 97A — Pressure Switch Settings (psig)
Table 97B — Pressure Switch Settings (Pa)
Relief Devices — All units have relief devices to protect
against damage from excessive pressures (i.e., fire). These de-
vices protect the high and low side.
Control Circuit, 115 V — This control circuit is protect-
ed against overcurrent by a 5-amp (sizes 030-090) or 9-amp
(size 105) circuit breaker. Breaker can be reset. If it trips, deter-
mine cause of trouble before resetting.
Control Circuit, 24 V — This control circuit is protected
against overcurrent by a 3.2-amp circuit breaker. Breaker can be
reset. If it trips, determine cause of trouble before resetting.
Gas Heat (48Z Only)
LIMIT SWITCHES — The maximum supply-air temperature
is controlled by a limit switch located in the gas section. The
limit is designed to trip at 100 F above the maximum tempera-
ture rise.
When the limit trips, 2 flashes occur on the IGC board. The
gas valve is deenergized. After cooling, the system will reset
and fires gas again. If four trips occur, the system shuts down
into Lockout and 4 flashes occur on the IGC board. The system
must then be manually reset by power down and power up of
the unit.
LIMIT SWITCH THERMISTOR (Staged Gas Unit
Only) — The limit switch thermistor is a factory-installed
component. It is located next to the lower limit switch. The
limit switch thermistor senses temperature at limit switch loca-
tion and prevents the limit from tripping while the unit is oper-
ating at low airflow.
ROLLOUT SWITCH — This switch senses any flame or ex-
cessive heat in the main burner compartment and deenergizes
the gas valve. If this occurs, the gas heating system is locked
out (7 flashes on IGC board) until the rollout switch is reset
manually. Reset rollout switch manually by powering down
and powering up of the unit.
When the rollout switch trips, it usually indicates a flue
blockage. Inspect the unit for any obstruction in the flue sys-
tem, for holes in the flue box, a defective hall effect sensor, a
defective inducer motor, or a loose combustion blower.
Compressor Removal — Access to the pump end of
the compressor is from the compressor side of the unit. Access
to the motor end of the compressor is from the inside of the
unit. All compressors can be removed from the compressor
side of the unit.
1. Disconnect power to unit; lockout power to compressor.
2. Close suction and discharge service valves.
3. Relieve refrigerant pressure into a refrigerant recovery
system.
4. Remove:
a. Fan-cycling pressure switch (FCPS)
b. High-pressure switch
5. Disconnect power wires at terminal box and disconnect
conduit.
6. Disconnect wires from crankcase heater.
7. Disconnect service valves from compressor.
8. Remove 4 locknuts securing compressor to the spring
assemblies.
9. Lift compressor off mounting bolts and remove.
Compressor Replacement — Perform the following:
1. Reverse procedure in Compressor Removal section to
end of Step 4.
2. Reinstall service valves and safety switches, and tighten
to torques as listed:
3. Leak-check and evacuate system, recover refrigerant.
4. Recharge system per pre-start-up and start-up sequences.
Recheck oil levels.
5. Energize crankcase heater for 24 hours prior to restart of
system.
IMPORTANT: After a prolonged shutdown or service
job, energize the crankcase heaters for 24 hours before
starting the compressor.
SWITCH CUTOUT CUT-IN
High 426 ± 7 320 ± 20
SWITCH CUTOUT CUT-IN
High 2937 ± 48 2206 ± 138
Fig. 51 — Typical Compressor Overtemperature
and High-Pressure Switch Locations
IMPORTANT: All compressor mounting hardware and
support brackets removed during servicing must be rein-
stalled prior to start-up.
TORQUE COMPRESSOR(S)
Tighten discharge valves to —
20-25 ft-lb (27- 34 N-m)
80-90 ft-lb (109-122 N-m) 06E-250, 06D-537
06E-265,275,299
Tighten suction valves to —
80- 90 ft-lb (109-122 N-m)
90-120 ft-lb (122-163 N-m) 06E-250, 06D-537
06E-265,275,299
Tighten the following fittings as specified —
120 in.-lb (13.5 N-m) High-Pressure Switch