Hello gang. I've got an issue I'm trying to diagnose, and some of the posting I've read on this site are very helpful. I'm the owner of the unit, and I've gone through multiple technicians who have been unsuccessful. I'm not on here to cut corners, and I'm no do-it-yourself'er. I'm currently working with a knowledgable tech that I trust, but he's running out of idea. And he's been working directly with the YORK technical service rep in our area.
So here it goes. Live it Phoenix, and it's been 110/day. Unit running fine all summer, turned off for 1 week vacation, and issues arose upon return. Unit is 3.5 ton YORK heat pump, circa 1985. Well maintained, and in generally good shape...just old.
When turned on, in AC mode, the inside blower would run, but neither the fan or compressor would start on outside unit. But this proved to be intermittent. Unit would sometimes start, but then would run short while and kick off, with the "EM Heat" light coming on. In general, it'd run in the cooler mornings, and error in the hot afternoons and evenings. I'm not sure the significance, but the pattern was beyond coincidence.
The YORK tech determined one of the sensors was bad (Ambient sensor, discharge sensor, liquid sensor, DS Defrost sensor). The tech suggested jumpering two pins in the control module, to take these sensors out of circuit. We did that, problem appeared to be solved, as the unit fired right up, and cooled without issue that night and next day.
End of next day, different problem (prob same problem, but now different manifestation given elimination of sensors). Now the outside unit fan motor always turns on, but compressor does not. Unit just blows warm air in the house. Like clockwork, three days in a row now, I leave the unit off until it cools down outside, then it fires right up and runs until the next day's afternoon. When it's running, air is ice cold and cools the house immediately.
Any direction would be great help. The current direction my tech has recommended was adding a "hard-start" kit, which I understand to be a higher charging cap? While this new cap can't hurt, I assume, I'm wondering about whether the reversing solenoid or the high pressure sensor might be to blame?
Lastly, if it ends up being the HP sensor, and assume the sensor works, any ideas on what temperature-related scenario could be creating the high pressure?
Thank you all, for your time.
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