3 ton Rheem heat pump, R22, manuf. date 1997
Customer complaint: Only getting heat from heat-strips as condenser
unit will not run in heat-mode.
When we (my assistant brother, Ernie) and I arrived this past Sunday, 2/14/10, I found the condenser disconnect lying on the ground; my niece had had another AC company out, tried to diagnose the problem, said they’d get back to them, but never called Becky back. I turned thermostat to heat & set it up to 85oF. The AHU came on fine, but when I inserted the disconnect at the condenser unit…. nothing happened. I hooked up my pressure gauges and pushed the reset button on the condenser unit….it started up and I watched the psig on high-side spike to over 375 then the condenser unit shut-down completely… I assume on high-pressure control.
Suspecting that heat was not being rejected at the AHU, I cleaned the coils to the AHU (I was surprised to see that they were pretty clean; although, I did find a caked filter indoors in the ceiling and removed it). I then pushed the reset button to the condenser, it started up, rose to 375 then cutoff on high pressure, again.
I cleaned the coils to the condenser unit (it was dirty); pushed reset button, started up, rose to 375 then cutoff on high pressure a 3rd time.
Called Bob Nolan at SSC. He said it was either overcharged or there was a restriction in the refrigerant line.
I checked the refrigerant lines, there were no crimps or obvious restrictions (although, I did not find a filter-drier at either condenser or AHU areas… that was odd!). I then switched the system’s thermostat to “cool” mode. The whole system came on and I ran it for 2 minutes in cool-mode… pressures appeared normal (260/70).
I then switched the thermostat back to ‘heat’ mode and the high-side pressure spiked and cut-off; I could hear the jet-sound of the RV, but could not determine if it was fully engaged in the heat-mode. I then recovered maybe a ½ pound of refrigerant (thus keeping high-side pressure down to around 260). While the condenser was running, I worked to remove refrigerant and kept the psig under control, the compressor started sounding strange (heard what seemed to be an internal hissing noise from the compressor), it then got real hot, and I assume cut out on IOL; I ohmed the compressor out, it was OL … C to R and C to S. We ran out of time and I had to go, so I assume the compressor cooled down and reset itself. I left XXXXX XXXXXke I found her – only getting heat from the heat-strips.
What just happened? Is it fair to say that the problem lies w/ the RV or the TXV at the condenser? How do you know if the RV is no fully engaged?