I had a local HVAC tech check my HVAC out. He was outside a short time, came back in and said I needed a new compressor. I said I'd have to talk to my wife to see if we had the funds.
I thought he was out there for REALLY short amount of time, something like 10 minutes. I wondered if he really checked anything at all. So, I got to reading this forum and a few others, and I did some testing and checking myself, and I don't think the compressor is bad at all--assuming I did the checking and testing right.
I swapped the thermostat with another identical thermostat on another system, and both thermostats work on the other system.
As the contacts on the contactor were burned and had a small patch of black soot surrounding each contactor, I replaced it with a Mars2 17311 24 volt Contactor Relay, 1 Pole 30 Amp. The compressor still didn’t run. It seems like, if the original contactor were actually bad, this should have taken care of it, but it didn’t. However, the compressor does come on if I push in the contact button in the center of the Mars2 contactor.
This Mars2 contactor seemed a little light and not as heavy duty as the original one (don’t know info on label as it was faded), so I thought I’d get another one that seemed to look and feel a little more like the original one. I am replacing it with a Cutler-Hammer C25CNB130T Contactor , 30 Amp , 1+ Pole , 24 VAC Coil C25CNB130T.
In the mean time, does anyone have any suggestions as to what else I should test and how?
Interestingly, on another forum, one reply said a compressor could be found to be bad in 10 minutes, but he didn't address the ohm readings I took. If I took them right they were as listed below. If understand the compressor ohming procedures correctly, the ohm reading from the COMMON terminal to START terminal and the ohms from the COMMON terminal to the RUN terminal, when added together should equal the ohms reading from the RUN terminal to the START terminal. They seem to as noted below.
The information on the data plates is as follows:
Payne compressor assembly
check for 24v to coil side of contactor..... You said if you push it in the system runs, well if your stat is set to cool and calling for compressor that will pull in the contactor if the it has 24v to the coil of the contactor.
Ohms look good and since it ran with the contactor pushed in it's not shorted internally. Could be a mechanical failure inside the compressor or it could be he misdiagnosed the problem. Call the company up and ask why the compressor was deemed to be bad.
call the cooling from the stat check for 24vs on the pair of low voltage wires going into the compressor...should have it there...see if you have a low or hi pressure switch might be open..find the hot R wire to get the contactor to pull in from the stat...trace the contactor 24v wire back from its slip clip..some thing is open...
I have had the same problem with my mothers central air unit. the compressor comes on when you push the contactor in. If you know for a fact that your thermostat is working properly and you hear the unit or the blower fan come on, try replacing the start capacitor. you will have to look at the schematic which should be inside the cover that you removed to see the contactor.
If you hear your compressor come on and begin to build pressure it probably is not your compressor which is faulty. I have replaced these on several units for friends, that part unsually cost around 30 bucks and is very simple to replace. It will probably cost you less than a service call.
Ac repair. You must actually give DIY repair advise to be allowed to have links to your company in your signature. Don't try to fool our members into thinking your a DIYer, and then post links to your company.
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