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Post by dustin on Jul 9, 2022 14:07:18 GMT
I just bought a 1950’s Montgomery wards fridge from a guy who said it works. I took it home and noticed all the wires were brittle and falling apart so I replaced the wire from the compressor to the junction box and the main power wire that plugs into the wall from the junction box. When I plugged it in I can hear the compressor kick on and run for a few second then shuts off. When it shuts off I can hear a click. I have had it running like this for an hour now and the fridge is very cold. I’m just wondering if the fridge is supposed to cycle on and off like this constantly or is there a issue I need to fix. I’m going to unplug it for now just in case something is wrong.
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Post by dustin on Jul 9, 2022 14:30:20 GMT
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marko
7 Cubic Foot
Posts: 140
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Post by marko on Jul 9, 2022 16:18:56 GMT
Hi Dustin, something is going on there. It MAY be cycling on the thermostat, but a few seconds on (how long off?), or short cycling, generally is not a good thing. Does the cycle time increase when you set the t'stat colder? Or does it still short cycle? It is hard to imagine that the box gets good and cold with just a few seconds of compressor run time. How's the frost look on the evaporator?
The compressor may also be cycling on the overload. It is hard to say without more testing. Did you lay the box down while transporting it? If so, let it stand upright for a day before running it again.
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Post by jake on Jul 9, 2022 21:01:49 GMT
Welcome to the forum, Dustin. What should be going on is with the inside of the refrigerator warm, like room temperature, and you turn it on the compressor should run continuously for 2 or 3 hours. Then when the refrigerator is at operating temperature it will cycle on and off every few minutes to maintain the temperature. Usually about 3 to 5 minutes on and about 10 or so minutes off. Did you replace the power cord with a 3 wire grounded cord? If you did, the ground wire from the new power cord should not be hooked up to the compressor! It should be bolted to the refrigerator cabinet. The 3 wires on the compressor are common, start, and run. Not hot, neutral, and ground like on a 3 wire power cord. When the compressor first starts up the start and run wires on the compressor are connected together at the compressor relay. When the compressor motor comes up to running speed, usually in a second or two of starting up, the relay disconnects the start wire from the compressor and the compressor continues to run on the common and run wires only. When the compressor shuts off the relay resets and is ready for the next time the compressor starts up. Is there a wiring diagram on the back of your fridge? If so can you post a picture of it? That's a very nice refrigerator too!! If the wires are not hooked up correctly the compressor is not running right and is tripping the overload. The overload will automatically reset after a minute or two. This may be what you're seeing and hearing.
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Post by dustin on Jul 10, 2022 1:31:28 GMT
Hi Dustin, something is going on there. It MAY be cycling on the thermostat, but a few seconds on (how long off?), or short cycling, generally is not a good thing. Does the cycle time increase when you set the t'stat colder? Or does it still short cycle? It is hard to imagine that the box gets good and cold with just a few seconds of compressor run time. How's the frost look on the evaporator?
The compressor may also be cycling on the overload. It is hard to say without more testing. Did you lay the box down while transporting it? If so, let it stand upright for a day before running it again.
thanks for the reply. It runs for maybe 10 seconds then off for a minute or two then it runs again for a couple seconds. The cycle time doesn’t increase any and there is no frost on the evaporator. The ice box is cold to the touch after it ran this way for an hour. The fridge was Put on it’s side for transport. The guy I bought it from said it would be good after an hour. I guess I’m a fool for believing him. Do you think it just needs to sit for 24 hours without being ran and maybe it will be ok?
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Post by dustin on Jul 10, 2022 1:44:50 GMT
Welcome to the forum, Dustin. What should be going on is with the inside of the refrigerator warm, like room temperature, and you turn it on the compressor should run continuously for 2 or 3 hours. Then when the refrigerator is at operating temperature it will cycle on and off every few minutes to maintain the temperature. Usually about 3 to 5 minutes on and about 10 or so minutes off. Did you replace the power cord with a 3 wire grounded cord? If you did, the ground wire from the new power cord should not be hooked up to the compressor! It should be bolted to the refrigerator cabinet. The 3 wires on the compressor are common, start, and run. Not hot, neutral, and ground like on a 3 wire power cord. When the compressor first starts up the start and run wires on the compressor are connected together at the compressor relay. When the compressor motor comes up to running speed, usually in a second or two of starting up, the relay disconnects the start wire from the compressor and the compressor continues to run on the common and run wires only. When the compressor shuts off the relay resets and is ready for the next time the compressor starts up. Is there a wiring diagram on the back of your fridge? If so can you post a picture of it? That's a very nice refrigerator too!! If the wires are not hooked up correctly the compressor is not running right and is tripping the overload. The overload will automatically reset after a minute or two. This may be what you're seeing and hearing. . thanks for your response. I did use a 3 wire cord but I didn’t hook up the ground wire anywhere. I carefully unhook and replaced each wire one at a time so I didn’t get them mixed up. I did take note that the original power wire was just 2 wires white and black and the compressor wires were white red and black. I should bolt the ground to the cabinet like you mentioned for safety purposes. The fridge is not cycling like you mentioned above. It only runs for 5 to 10 seconds then I hear a click and it sits for a minute or two and repeats. I believe it must be cycling off the over load switch like you mentioned. Would this happen if I laid it on its side then tried to run it after an hour of sitting and is the black box all the wires go to the over load switch? All this refrigerator stuff is new to me I have done electrical wiring before in the house so I am fairly confident that is correct. Could the over load switch be bad?
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Post by dustin on Jul 10, 2022 1:52:06 GMT
Not a bad purchase for 80 dollars anyway the guy that sold it to me said someone else wanted to buy it and turn it into a smoker. I’m glad I was able to save it from that.
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Post by 508gm1 on Jul 10, 2022 11:08:33 GMT
The symptoms you describe sound like an issue with the start relay not removing power to the start winding on start-up. www.youtube.com/watch?v=ook8DVWYZIgThis is one of David's most helpful videos. Fast forward to the 7 minute mark. I am remembering a video specific to the relay only but I cannot find it.
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Post by jake on Jul 10, 2022 11:24:53 GMT
Definitely sounds like the compressor is trying to start but is tripping the overload for some reason. Don't leave it plugged in like that. The first thing to do is take resistance readings at the compressor terminals. This will tell us which terminals are which (common, start, and run). Get the resistance value between black and white, red and white, and red and black. You can also check the terminals on the compressor relay. They're sometimes marked "C,S,R". Or "L,S,M" (Line, Start, Motor). Transporting the fridge on its side is a no-no for two reasons. There's oil in the bottom of the compressor that needs to stay in the bottom of the compressor. When the fridge is laid down the oil can run out of the compressor into the refrigerant system where it doesn't belong and can get trapped there. Plus on a vintage machine there's bound to be some dirt or debris in the oil that can get stuck in the tiny passages of the refrigeration system, especially the capillary tube, and cause a blockage. Either of these scenarios will cause the compressor to run continuously with poor cooling or no cooling. Laying the fridge down also puts undue stress on the refrigeration lines and they can break in transit. The problem you're seeing is an electrical problem though. Hopefully it's just a bad relay and not a stuck compressor. Take those resistance readings and let's see what we have. It might even be a bad connection that happened during shipping.
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Post by jake on Jul 10, 2022 11:40:05 GMT
The formula that David explains in his video for checking the resistance values to determine which terminals are which on the compressor applies to your Montgomery Ward refrigerator too.
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Post by dustin on Jul 10, 2022 14:21:05 GMT
The formula that David explains in his video for checking the resistance values to determine which terminals are which on the compressor applies to your Montgomery Ward refrigerator too. ok sounds good thanks for the help. I will check out the video in the link you gave me. Looks like I will have to dig out the ohm reader. I’ll let you know what I find out.
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Post by dustin on Jul 10, 2022 15:34:35 GMT
So I don’t know if I had my ohm reader on the right setting because I’m not very fluent with using one but this is what I got. With all the wires disconnected from the compressor I tested red to black 11.4 ohms, red to white 09.1 ohms and white to black 02.6 ohms.
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Post by dustin on Jul 10, 2022 15:41:07 GMT
I also put the ohm reader on the box and took some pictures so you can see where I had my ohm reader set. I don’t know if I’m supposed to be getting these readings from the box but I figured I would post it as well. Any help is appreciated thanks.
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marko
7 Cubic Foot
Posts: 140
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Post by marko on Jul 10, 2022 16:53:23 GMT
I also put the ohm reader on the box and took some pictures so you can see where I had my ohm reader set. I don’t know if I’m supposed to be getting these readings from the box but I figured I would post it as well. Any help is appreciated thanks. Those motor readings look good.
The relay however, looks as if it may be mechanically damaged and the darkened brass strip looks to have been overheated, though it is difficult for me to tell from the photographs.
I would say you need a new relay.
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Post by jake on Jul 10, 2022 17:06:30 GMT
Yes, I agree. Those are good readings for the compressor windings. "The box" is the compressor relay and I bet the contacts inside are worn out. Can you remove the cover and show us the inside of it? There's two sets of contact points. One for the start winding of the compressor and one for the overload. Usually what happens is the start contacts get worn out and stick together. This keeps the start winding in the circuit, when it shouldn't be and trips the overload to prevent damage to the compressor.
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