Original message
| jocko
 |  "Need Help Please: Compressor Cutting Out"
, posted Sat 13 Aug 12:43  
Glad I found the site. Searched for answers, decided to post a question. I'll try to be as specific as possible.
Tempstar "5000" series dual zone heat pumps circa 1995. The upstairs unit is nowhere near keeping up with this heat. This unit has been inspected twice recently by repair guys who could not find the problem. Paid for the calls and got nothing. Here are the symptoms:
It is hot upstairs. Turn on the thermostat, the relay will click and the fan will turn on. The thermostat is calling for the compressor. Go outside, the compressor will turn on and spin for a brief while, but will turn itself off. Fan keep on going. The shut-off is not consistent, sometimes it will run for an extended period. Sometimes as little as 20 seconds. Uver time, the unit produces very little cooling. I assume something in the compressor/condenser system is tripping out, but have no idea.
The first repair guy was an idiot. He said my thermostat was off by 7 degrees, I needed a new one. He looked at the wiring, put his gages on, and added a little freon. Tried to sell me a thermostat.
The second guy was better. He said the charge was fine and the "pressures" looked good. He questioned the position of the water pan float switch in the attic unit and repositioned. At the time, the compressor ran fine and I though he had found it. However, it soon went back to the old ways. I checked the float switch myself and it seems to be actuating properly.
Assuming these guys know how to install and read pressure gages and a voltmeter, what could they be missing? I did not know about the float switch, what else could cause the unit to shut itself off? A bad sensor? Is there any way to interrogate the electronics?
It is not lack of return air
It is not freezing up.
It is not clogged filters.
Please advise.
Thanks in advance,
jocko
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Replies:
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| bubbad
| "Re(1):Need Help Please: Compressor Cutting O" , posted Sat 13 Aug 13:38
jocko, it's not easy troubleshooting intermittent problems. What kind of thermostat do you have? I've seen thermostats that fail in the red to yellow circuit, but maintain everything else, (reversing valve, indoor blower), but not the outdoor unit. Could be the low voltage wiring, or a weak contactor in the outdoor unit. If you lose the low voltage to the outdoor unit, (lets just say the thermostat is not keeping that circuit closed) then if it's restored, the heatpump circuit board will wait 5 minutes before it allows the unit to come on. It may also be the defrost board failing. Best thing would be for the tech to be able to be there when it stops so they could see what's stopping it. I know, I know, it will not do that while they are there. : )
bubbad
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| | MasterTech
| "Re(2):Need Help Please: Compressor Cutting O" , posted Sat 13 Aug 14:24
If the fan is running outside but its not cooling(assuming heaters not coming on) i would assume compressor is out for some reason. I would see if hard start device is working and proper for that unit. Next would be contactor. And bubbad is right it will be a hard problem to find.
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| | jocko
| "Re(3):Need Help Please: Compressor Cutting O" , posted Sat 13 Aug 18:59
The compressor motor stops running. When the compressor motor turns, the unit cools fine. "Fan" was referring to the air circulating fan.
What is the control voltage for the system? I noticed the tech was handling the wires, I assume they are low. What constitutes hi and low? Are there any analog signals or just on / off? Where can I get a diagram of the system? With a diagram I could probably figure it out.
Thanks,
jocko
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| | bubbad
| "Re(4):Need Help Please: Compressor Cutting O" , posted Sat 13 Aug 21:06
Control, or low voltage is the 24VAC that comes from a transformer in the airhandler. It's what powers your thermostat, circuit boards, and ultimately brings in relays that control the high voltage end of it, (indoor blower, compressor, and outdoor fan). There should be wiring diagrams in the airhandler, and in the outdoor unit. If you remove any covers, be sure to turn of the breakers because there is 240VAC in both units. I assumed you meant the indoor blower was running, and the outdoor unit stopped completely, but wasn't really sure. I would check all connections from the thermostat, to the airhandler, and to the outdoor unit. When the outdoor shuts down (when it shouldn't), that's when you can tell if you lost you call for cooling, or if the call is still there, but it's not getting through the defrost board. If you're not comfortable with electricity, I would advise you not to poke around in there just to be safe. Hope this helps.
bubbad
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