1/29/2016 - Heat Pump Packaged Unit
Complaint: Not cooling, blowing warm air Problem: First stage compressor not energizing, second stage compressor will come on after a delay. Blowing warm air in both heat and cooling. After verifying that all wiring was correct and all connections were tight, I isolated the problem to the contactor on the first compressor. When leads from compressor one to contactor one were switched to contactor two and compressor twos leads were moved to contactor one, compressor one was able to energize and compressor two failed to energize. Leads were moved back to original wiring and I manually closed the contractors one at a time. When contactor one was closed, I could hear the compressor humming, but would not start. I did this several times until I noticed a piece of the contactor casing moving when I pressed the button to close it. I disassembled the casing, removed the plastic piece. Reassembled and tested it again. The compressor then energized properly. I tested the system in cooling mode again, and system was still putting out warm air. I suspected the problem was with the reversing valve solenoid or the valve itself. I isolated the solenoid and connected its leads to a test transformer and was able to energize it without problems. I then reconnected the leads and verified that it was wired properly to energize on a call for cooling with this system. Having ruled out the solenoid as the source of the problem I then suspected that the issue was with the thermostat. I isolated the O terminal lead and measured voltage from R when cooling mode was energized. No voltage was recieved. I then jumpered the reversing valve solenoid into the R terminal and when the system turned on, the reversing valve energized and was able to put out cool air. The thermostat is being exchanged and will attempt to verify the solution tomorrow with the new thermostat. Solution: Removed debris from contactor and replaced thermostat