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DanDaMan 03-13-2013 10:19 PM

Please help diagnose why my fridge compressor is not running
OK, I've done some googlin' and diagnosing on my small refridgerated cooler. Basically about 6 months ago it stopped cooling and instead starting warming. I unplugged it since and only recently started diagnosing it.

So I exposed the 3 prongs on the compressor and did a resistence test with multimeter. From start-to-common I have 13.9, from run-to-common I have 9.9 and from start-to-run I have 23. I've reading that the two smaller numbers are suppose to add close to the bigger number (which mine does) but that the two smaller numbers are supposed to be very similar (which mine are not). What do my numbers mean - is my compressor dead?

Second, I'm confused on the wiring and wondering if maybe I have a switch problem, or problem with the start relay or capacitor. My current setup is that I have a neutral (blue) and a hot (black) wire that connect to my relay/capacitor and these two wires (blue/black) are feed from the dial switch that turns the fridge on/off and controls the temp. I tested the blue/black wires connected to the relay/capacitor and found that both the black (hot) and neutral (blue) is HOT (110V) when the dial switch is Off. If I turn the dial switch on (regardless of the temp setting) then only the black stays HOT (110V) but not the neutral. Is this normal? Also, my relay and capacitor are actually 2 separate units. Can someone please confirm which one gets the black/hot and which gets the blue/neutral? Lastly, how can I test the relay and capacitor, and exactly what is the job of the capacitor as mine basicaly has an 'out' wire which is HOT too (should the out HOT perhaps be a higher voltage or something)? My relay has two 'out' female ports which plug into the run and start terminals on the compressor. If I stick my multimeter up the relay female ports, how can I test if it is working right.

Any advice would be greatly appreciated.


joecaption 03-13-2013 10:23 PM

No make and model?

DanDaMan 03-13-2013 10:46 PM

It is actually one of those small barrel coolers you see at the local convenience store, normally stocked with energy drinks and decalled the same. Model is WS75 and can't recall manuf but somethng like QBD. Below is a link I quickly found that shows a pic.


DanDaMan 03-13-2013 11:29 PM

Did some more testing, and don't think it is the compressor. I tested if the windings are grounded, and none of the 3 terminals are. And further reading suggests that although the two smaller resistence readings are slightly different, since they add up to the larger, that my compressor is fine.

My relay is nort the coil type, so I think they call it a solid state. Any way to test if it is good, or whether my issue is the capacitor.

Also based on my first email, would appreciate knowing if my on/off switch is proper by the way it turns the neutral to being hot when the switch is on the off position and then not being hot when in the on position.


DanDaMan 03-14-2013 12:11 AM

Did more reading. Realized what I was calling a capacitor was actually my overload. My cooler does not have a capacitor - does that make sense? Testing the overload and seems fine (has continuity / closed on the 'out' wire and on the in port. Still trying to figure out how to test my relay (it does not make any noise when shaking it, which I understand is a sure way to identify a bad one). Could it still be my wiring with the hot and neutral coming from the dial switch?


DanDaMan 03-14-2013 12:48 AM

Last update - I promise.

OK, did more reading and confirmed the neutral connects to the overload which connects to the common on the compressor. The relay connects to the hot which then has the two ports which connect to the start and run ports on compresor. Wired it up this way and just as before the compressor just hums for about 10 secs and then the overload clicks on and turns off power - about 30 seconds later overload closes again and the compressor hums again. Thus confirmed the overload is fine, and confirmed earlier the compressor passed the resistence and ground test (so it should be OK). Still can't find a capacitor - does this shoudl right?

Lastly, if I understand right the start relay has the two ports (start and run) since the compressor needs both to get 110V hot to start the compressor but once started the relay turns just one of the ports on (likely the run) since it now needs less power. Is this right? If so, to confirm 100% that my compressor will run again, can I directly connect the hot wire to the start and run terminals on the compressor and then plug in for a few seconds? Will this damage the compressor? Can't see hy or how, since that is what the relay is doing anyway (if it was working), so wouldn't this test just be a 100% way to confirm the relay is bad if the compressor were to start running?


hardwareman 03-14-2013 08:21 AM

are you getting voltage to the relay, if so then your relay is probably bad. There is no way to test these, you'll just have to buy a new one and take the chance

DanDaMan 03-15-2013 10:44 AM

Did some more reading and testing.

Yes, I've tested the voltage onto the neutral and hot going into the relay and overload and it is good. I tested the overload for continutity and it is good. I even tested the relay ports and the voltage is going through. Lastly I opened up the relay and the small disc inside is good and has continuity.

After reading tons, and testing everything with no success I decided to try to give the compressor power direct without the relay or overload. I knew it could fry the start winding if left on for more than 3 seconds but thought I would try and just see if it started in the first few seconds after plugging in. So I put my neutral direct to the Common on the compressor and connected wires on the Run and Start direct to the hot. Plugged it in and same old hum. Tried it several times (for 5 seconds each) and same hum. Even tried to switch the hot and neutral the other way around and same hum.

I assme that means my compressor is bad, but still makes no sense. My resistence test passed, and I DO NOT have connectivity on any of the ports when touching to the body of the compressor (and yes I did scrap off the paint to get down to bare metal). Plus if I did have a short, would my house breaker not have tripped when I did the direct power attempt.

So I would really like some advice. My compressor passed all the tests, but will not start. Any other ideas - should I try the old hammer trick?


hardwareman 03-15-2013 12:23 PM

it will not start without the relay, buy a $15 all in one unit and try it. Just because the windings ohm out correctly does not mean that the compressor is good. It could be "stuck", that is where the 3 in 1 unit will also help out as it has a built in start capacitor for a little extra starting torque

DanDaMan 04-03-2013 08:26 PM

Ok, bought a hardstart/kickstart off ebay and tried it out. Made no difference but I'm not sure I wired it right or if it is even working.

It is one that has a relay built in, but it only had 2 wires instead of 5 like others I've seen. Instructions said to connect each wire to the run capacitor. Others I've seen have the white, red and black wires but this one just the 2 wires. Being that my fridge has no run capacitor, I wired it up like this:

1) my neutral (off the power wire) goes to the neutral port on the compressor
2) one wire from the hardstart (which is direct from the port of the hardstart) goes to the start port of the compressor
3) the other wire from the hardstart (which comes from the relay of the hardstart) goes to the run port of the compressor AND splits to also the Hot of the power supply.

Note that I tried it the other way around, and still nothing. Both ways just humming, but as my posts above mention the compressor is passing all the tests so I'm now questioning if the hardstart I got is good or if I messed up wiring it up.

The hardstart is a Articco STT-6.

I'm questioning if the hardstart is good because after trying it out (and leaving it plugged in after install for 5+ minutes, there was no charge on either of the wires. Or at least there was no shock when I touched and removed the unit. Should the capacitor in the hardstart not store a charge??? Is there anyway to test the capacitor with a multimeter?


hardwareman 04-04-2013 02:54 PM

what you bought was not a 3 in 1 hard start kit I believe what you bought was a start capacitor only. Articco only makes products for commercial refrigeration and airconditioning equiptment. You need a unit that is a start relay and cap look at Supco products, but I would quess by this time you've already fried your compressor.

DanDaMan 04-05-2013 08:49 PM

OK, I give up. I'm still suspicious that my compressor is good as it passes all the tests. But since I can't gte it started I will convert my electric barrel cooler to be water tight inside and just use ice.

But I plan to remove the compressor and open it up and take a look inside. My theory is if its dead there is not harm in opening it up and screwing with it.

So my question. The cooler uses r134a. Is it OK to cut/snip the 2 tubes on the compressor so I can remove it? I know with R12 you can not do it legally without a special kit, but is it ok with r134a? Are there any dangers of cutting it?


DanDaMan 04-06-2013 11:56 PM

well, got the compressor out and removed the top by my grinder. Sure enough the shaft is seized which is why it was just humming but the compressor was passing the usual tests.

What caused the shaft to seize?


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