Demand Defrost Control
The control will begin the 3 minute time delay upon a Y call from the thermostat. After the time delay expires; the compressor contactor will be energized as long as the high and low pressure switches are closed. If either switch is open after the delay expires; the compressor will not energize and the respective fault code is displayed. If the high pressure cutout (HPC) switch opens while the compressor is energized; the compressor will de-energize immediately and the 3 minute anti-short cycle delay begins.
The low pressure cutout (LPC) switch is bypassed for the first 90 seconds of compressor run time; if the low pressure switch remains open after the 90 second delay; the compressor will de-energize and the 3 minute anti-short cycle delay begins. The compressor will not be allowed to re-energize until the anti-short cycle delay expires and both pressure switches are closed. If either pressure switch opens 3 times during the same Y call; the control will enter a hard lockout and flash the respective code.