[coolelroy]

About 6 months ago I bought a used fridge for my garage. It worked great until this week. It has stopped cooling and makes a humming sound for about 2 seconds and then makes a click. This is repeated every couple minutes. Both fans are running and the lights work.

The terminals on the compressor are not grounded to the chassis or copper lines. I checked ohms between start, run and common, the reading for start to common + run to common = run to start reading.

While in the back of the fridge I noticed that it has a Supco 3 in 1 relay overload start capacitor which I assume is a replacement part, not original.

This fridge has been in my garage and it has been very cold [Indiana]. Could the cold have caused the Supco 3 in 1 to fail due to the compressor being cold and hard to start? Has the compressor died?

Any ideas what is wrong or what else I need to check? Please provide details as I'm not a real repairman. I don't even play one on TV.

THANKS, coolelroy

[richappy]

Look for my article in the search box "Are 3n1 relays thart bad" .
For the newer 1/5 HP compressors, the use of a 3n1 hard start device will blow out the compressor during power fluctuations. The device will greatly exceed the compressor peak power ratings and also any electronic unit in the fridg. like a adaptive defrost board!! Also, if he failed to wire in the run capacitor (if your fridg. had one) that will also blow out the compressor windings.

[coolelroy]

I made a test cord and tried to manually start the compressor.
Test cord like this http://www.applianceaid.com/images/testcord.jpg
As soon as I plugged the cord into the outlet the fridge started making a humming noise. [powering common and run] When I applied power from the run wire to the start terminal on the compressor nothing happened.

This means? [I assume I am screwed but would like an expert opinion]

[richappy]

Make sure you wired it up right. The compressor pins are in a triangle with the common pin on top, but sometimes on the bottom. If on top, the run and start pins are on the bottom. To confirm, measure the ohms from the common pin to the two bottom pins, start winding should be like 5 ohms, the run winding like 3 ohms. Resistance between start and run is the total of the two, like 8 ohms. If it is wired correctly, and no start winding current, your compressor start winding is blown open.
Caution, do not run start current with no momentary start switch or the start winding will blow open. Also, do not run the compressor for a long period without the run capacitor if the fridg. had one.

[richappy]

Caution. The test circuit shown is very old as all modern compressors do not have a start capacitor.
I have a test circuit similar to this. If you use this circuit, it is rather easy to blow out the compressor windings if you press the start switch too long. The compressor only needs start current for less than a second. Well over a second and the windings will draw excessive current and blow open! For insurance, I would add a modern start device in series with the start winding.
I am not really sure how long before blowout as I do not have a bad compressor to test right now. The next bad compressor I see, I will test it.