Goodman ComfortNet ASXC Series Service Instructions Manual page 31

SYSTEM OPERATION
TM
DEFROST CYCLE - COMFORTNET MODELS
The defrosting of the outdoor coil is jointly controlled by the
UC PCB and the outdoor coil temperature (OCT) sensor.
The OCT sensor is clamped to a feeder tube entering the
outdoor coil. Defrost timing periods of 30, 60, 90 or 120
minutes may be selected via the dipswitch settings on the UC
PCB. In a communicating system, the defrost timing periods
can also be selected in the communicating thermostat user
menu. During operation, if the coil temperature is low enough
(approximately 31° F), the microprocessor will accumulate
the compressor run time. When the total compressor run
time reaches 30, 60, 90 or 120 minutes, and there is a call for
heat, the PCB will initiate a defrost cycle. When the
microprocessor detects the coil temperature to be high
enough (approximately 75 0 F), or 10 minutes of maximum
defrost cycle time has elapsed, whichever occurs first, the
defrost cycle is terminated and the timing period is reset. The
field service personnel can also advance a heat pump to the
defrost cycle by simultaneously pressing the "TEST" button
and the "RECALL" button on the UC board.
Use the dipswitches to select defrost time interval (30, 60, 90
or 120 minutes) See chart below
31