OPERATION - DEFROST CONTROL

OPERATION - DEFROST CONTROL
Timing
When operating, the power to the circuit board is controlled
by a temperature sensor which is clamped to a return bend
on the outdoor coil. Timing periods of 30, 60, or 90 minutes
may be selected by connecting the circuit board jumper wire
to 30, 60, 90 respectively. Accumulation of time for the timing
period selected starts when the sensor closes (approximately
28°F) and when the wall thermostat is calling for heat. At the
end of the timing period, a defrost cycle will be initiated,
provided the sensor remains closed. When the sensor opens
(approximately 65°F), the defrost cycle is terminated. If the
defrost cycle is not terminated due to the sensor temperature,
a 10 minute override interrupts the defrost period.
Field Testing / Trouble Shooting
A. Run unit in heat mode.
B. Check unit for proper charge. Note: Bands of frost indicate
low refrigerant charge
C. Shut off power to unit