Controls, Start-Up, Operation, Service and ... - Climayoreo

Recommended Cooling Time
(Minutes)
Fig. 91 — Advanced Scroll Temperature
Protection Label
120
110
100
90
80
70
60
50
40
30
20
10
0
0 10 20 30 40 50 60 70 80 90
Compressor Unloaded Run Time (Minutes)
*Times are approximate.
NOTE: Various factors, including high humidity, high ambient temperature,
and the presence of a sound blanket will increase cooldown
times.
Fig. 92 — Recommended Minimum Cool-Down
Time After Compressor is Stopped*
Crankcase Heater — Each compressor has a crankcase heater
to prevent absorption of liquid refrigerant by oil in the crankcase
when the compressor is idle. Since 115-v power for the
crankcase heaters is drawn from the unit control circuit, main
unit power must be on for the heaters to be energized.
IMPORTANT: After a prolonged shutdown or service
job, energize the crankcase heaters for 24 hours before
starting the compressor.
EVAPORATOR-FAN MOTOR PROTECTION — A manual
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 overtemperature.
They are also protected against a severe overcurrent
condition by manual reset, calibrated trip, magnetic circuit
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 — Settings for these switches
are shown in Tables 104A and 104B. If either switch trips,
that refrigerant circuit will be automatically locked out by the
controls. To reset, recycle control power to unit.
Table 104A — Pressure Switch Settings (psig)
SWITCH CUTOUT CUT-IN
High 650 10 500 15
164
Table 104B — Pressure Switch Settings (kPa)
SWITCH CUTOUT CUT-IN
High 4482 69 3447 103
Relief Devices — All units have relief devices to protect
against damage from excessive pressures (i.e., fire). These devices
protect the high and low side.
Control Circuit, 115 V — This control circuit is protected
against overcurrent by a 10-amp circuit breaker. Breaker can
be reset. If it trips, determine cause of trouble before resetting.
Control Circuit, 24 V — This control circuit is protected
against overcurrent by two 10-amp and four 3.2-amp circuit
breakers. Breakers can be reset. If a breaker trips, determine
cause of trouble before resetting.
Gas Heat (48P 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 temperature
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 location
and prevents the limit from tripping while the unit is operating
at low airflow.
ROLLOUT SWITCH — This switch senses any flame or excessive
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 system,
for holes in the flue box, a defective hall effect sensor, a
defective inducer motor, or a loose combustion blower.
Compressor Removal — All compressors can be removed
from the compressor side of the unit.
IMPORTANT: All compressor mounting hardware and
support brackets removed during servicing must be reinstalled
prior to start-up.
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. Disconnect power wires at terminal box and disconnect
conduit.
5. Disconnect wires from crankcase heater.
6. Lift compressor off mounting bolts and remove.
Compressor Replacement — Perform the following:
1. Reverse procedure in Compressor Removal section.
2. Leak-check and evacuate system, recover refrigerant.
3. Recharge system per pre-start-up and start-up sequences.
Recheck oil levels.
4. Energize crankcase heater for 24 hours prior to restart of
system.