overload relay

[johnnicinco]

Hi
I have a refrigerator that every two hours will fail to start the compressor and a quiet buzzing sound occurs. The buzzing stops after half a minute or so, giving up trying to start the compressor when it does. If I go unplug it and wait approximately 1/2 hour, it starts up fine with no buzzing. The fridge is great, nice and cold. The schematic shows it has an overload PTC Relay and I have replaced it, which changed the amount of time it took for the compressor to have a failure with the buzzing to three hours instead of two. If I leave it plugged in it just buzzes for 30 seconds and then quits and then 10 minutes later it buzzes again and so on. What could it be? The schematic shows the external capacitor as a run cap.

[nike123]

Check running current against specifications of that compressor.

[NoNickName]

If it's single phase, may be the starting capacitor failing.
If it's a three phase, then it's probably a wet start.

[tonyelian]

hi
it seems like ur compressor is gone it became too hot after a while &pulls more ampere so the over load cuts out

[frank]

How old is the refrigerator and what gas is it running on?

[johnnicinco]

hi
it seems like ur compressor is gone it became too hot after a while &pulls more ampere so the over load cuts out

I thought it might mean the pressure was too high that the compressor was trying to kick in against, and letting it sit for a few allowed the pressure to equalize, thus the thermostat was telling it to kick in too soon. I forgot about winding resistance increasing with temp. That could be it, and to test I just need to see how many amps its drawing when buzzing, right? Or I could measure the resistance right after it cycles off, right? I measured the windings when it was cool enough to start and they measured 4.63, 9.62, 5.76. I wonder why the two don't add up to the one? Is it because one winding is partly shorted to ground?