I have a York Stellar 2000 series Heat Pump model E1CS add-on system to a gas furnace. The heat pump had been working fine for a great many years. It now has problem in the cooling mode. When the system has not been running for many hours (such as at the start of the day) and the whole system is cold (the compressor, all lines, etc are cold to the touch), it would run for a few minutes then the pump shutdown. After that “initial run”, about half hour to hour, it would restart and run for a 15-20 seconds then shut down again. Then another half hour to hour later, it again restart and run 15-20 secs then shut down. The cycle repeats. The outside of the compressor is very hot to the touch. I have verified the following:
About 24 volts is present at the solenoid controlling the reversing valve during “cool mode”, and 0 volt at this solenoid during “heat mode”. I hear the solenoid click and a swoosh sound when switching between heat-cool, cool-heat. From this I assume the reversing valve works fine???
During heat mode (no problem running for 5+ minutes or longer), the system produces heat, and during cool mode (at least while it is running) the system generates cold air. So I assume the compressor is o.k???
When the whole system is not running the low side pressure is about 125 psi (R22, 90F ambient). This probably is the same on high side also since everything settles after the system is not running for hours. In any case, at least the system has enough refrigerant to produce heat and cold air.
The outside and inside condensers and cooling fins are clean. The big cooling fan atop the heat pump works fine.
During the cool mode when it ran for a few minutes, I could feel the low side pipe got very cold then gradually heated up until the heat pump shut down. This does not seem right, beside shutting down after 15-20 seconds.
Thank you for any suggestion!