HP - E 2
Sump Heater
Overview
Sump heat protects the compressor from liquid
migration. Liquid migration occurs when refrigerant
migrates during off cycle periods into the compressor
shell. Keeping the compressor shell warm during off
cycle periods can prevent liquid migration.
Troubleshooting
If the sump heaters fail to energize, the compressor
may fail to start or may have trouble starting after off
cycle periods.
Sump heater fails to energize
Step 1
Make sure the system operating parameters are met
for Sump Heater operation to occur. There should be
no call for cooling or heating compressor operation.
The compressors should be off for at least 30 minutes.
Outdoor air temperature should be below 75F and the
ambient sensor within the proper temperature range.
Line voltage should be present to the outdoor unit.
Step 2
Check for 24 volts at the SHR 24 volt terminals (Figure
1). These terminals will have a yellow and blue wires
and are identified on the relay as terminals 1 and 3.
There should be 24 volts present if a call for sump
heater operation is required. If 24 volts is present at
terminals 1 and 3 of the Sump Heater Relay, continue
to Step 3.
Figure 1
If voltage is not present, the Integrated Control Board
is defective. If voltage is present, there is a break in
the wiring between terminal T2 of the Integrated Control
Board and the connection at the Sump Heater Relay.
Step 3
Check for line voltage across the Sump Heater Relay
at terminals 2 and 4 of the relay (Figure 3).
If voltage is not present, check for 24 volts at the
Integrated Control Board terminal T2 to ground (Figure
2).
Figure 2
Figure 3
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