1950 Coldspot fridge - Hot wire relay

bad_nails

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I have what I think is a 1950 coldspot fridge. Pulled it out of my grandparents ranch house a few years ago plugged it in thought it was working perfect a few days later discovered it would randomly stop working. Wouldnt keep cold and the light would go off with very little movement of the fridge. We did some wire testing then. Couldnt figure it out decided we might need to rewire it and let it sit till today. I started pulling apart the front, the button for closing the door had a wire crimped in the plastic and was loose at the connection. I fixed it plugged it back in light works like a charm now. However my compressor won't turn on now. When I tested my voltage I have 120 into the fridge but at the compressor and leaving the hot wire relay I no longer have 120. So I'm thinking that hot wire relay has gone bad. Does this sound correct? And if so where do I find a new one or one compatible?
 

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Dan O.

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bad_nails said:
I have 120 into the fridge but at the compressor and leaving the hot wire relay I no longer have 120.

Did anyone check for power getting TO the relay?




.
 

bad_nails

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Yes 120 at the relay. I believe leaving the relay to the compressor I got a reading of 19. Hence why I'm thinking the relay is bad
 

Dan O.

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If there's definitely power to the relay but none from it to the compressor, it does sound Iike it might be defective.

It's odd that it was working previously, before your service. A light switch wiring shouldn't affect operation of the compressor.

Dan O.
 

bad_nails

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It only worked spontaneously before. One day it would be cold, the next warm. Bumping the fridge or opening and closing the door we could get the light to come and go. Where do I buy a new relay? I can't find parts anywhere and can't find anything to cross reference compatible parts
 

Dan O.

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Where do I buy a new relay? I can't find parts anywhere and can't find anything to cross reference compatible parts
You likely won't find an exact replacement. You'll probably have to wire in a universal solid state relay/overload asm. Rick described how to do that is this previous forum message:


He recommended the RO41 relay/overload (aka TJ90RO41) be used however is it for a 1/4 HP compressor. Most manual defrost refrigerator models use a much smaller 1/8 HP compressor in which case the RO81 relay overload (aka TJ90RO81) may be a better match. They're both wired (and look) the same.

LINK > RO81 Universal 1/8 HP Relay/Overload


Dan O.
 

bad_nails

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I have another question now that I have the part here. When placing the new wires on the compressor the original wire harness had r, b, and w (first picture). I had originally thought they were telling me where to place the new wires; r for red wire, b for black wire, and w for white wire, but after looking at this drawing (second picture) I'm thinking maybe not. In this image the black wire is connected to the w, white wire to the r, and red wire connected to the c. Can you please advise which what I'm suppose to connect to compressor
 

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Dan O.

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That wiring diagram is for a Frigidaire refrigerator not yours. It may not necessarily be the same as yours. You're best to figure out the wiring to the compressor yourself.

You can determine which compressor terminal is which by measuring the resistance between 2 pins at a time. The lowest resistance will be between common and the run (aka 'main') winding. The second lowest will be between common and the start windings. Between the run and start terminals will measure the highest (you're actually measuring both start and run windings together).

image.jpeg

Figure out which terminal is which and then wire the relay according to the instructions that came with the relay


Dan O.
 
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