Service; Capacity Control; Time Guard Ll Circuit; Crankcase Heater - Carrier 38AF Series Installation Manual

10

SERVICE

Capacity Control –A suction pressure-actuated unloader controls 2 cylinders and provides
capacity control. Unloaders are factory set (see Tables l.), but can be field adjusted as described in
the 2 following sections.
Time Guard ll Circuit – Prevents short – cycling by providing a delay of approximately 5 minutes
before restarting compressor after shutdown from safety device action.
On start-up, the Time Guard II time causes a delay of approximately 3 seconds after thermostat
closes.
On compressor shutdown, the time recycles for approximately 5 minutes. During this time, the
compressor cannot restart.
Refer to Fig. 8 and to label diagram on unit.
Fig.8 - Timer Sequence chart
Crankcase Heater – The heater prevents refrigerant migration and compressor oil dilution during
shutdown whenever compressor is not operating. It is wired into the control circuit. and cycles with
the compressor; the heater is off when compressor is running ,and on when compressor is off.
Both compressor service valves must be closed whenever the crankcase heater is for more than 6
hours. The crankcase heater is operable as long as the control circuit is energized.
Outdoor 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
reinstalled and be sure the fan guard is in place before starting the unit. Fan motors have
permanently lubricated bearings.
38AE010-015
38AE010-015