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Thread: run / start capacitor issue
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11-09-2010, 10:37 PM #1
run / start capacitor issue
Hi,
I have a small refrigeration unit used to cool a soda machine. It’s been off for some time. When I tried to start it up again, the compressor doesn’t seem to start. The condensing fan starts, and every 30 sec or so, I can hear the capacitor click as to start the compressor, but it doesn’t start. The fan seems to change speeds / slow down or speed up when the capacitor clicks. I’m not sure if it’s the capacitor or the compressor.
Any thoughts would be great.
Thanks.
Mvtop.
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11-09-2010, 11:19 PM #2
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Re: run / start capacitor issue
Capacitor doesn't clicks. Starting relay clicks.
It is compressor blocked.
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11-09-2010, 11:24 PM #3
Re: run / start capacitor issue
If you haven't already done so turn it off. The clicking is the klixon, a bi metalic doodad that senses compressor body temp and the current it is drawing and turns off the comp till the klixon cools an resets, it will do this quicker with just a current trip than an over temp trip.
Could be either a duff comp or duff start relay/cap, if you have got a suitable selection of testers you can check the cap and the current on the start winding and also the winding resistances, if not then you can try a new relay and cap and cross your fingers.
If it has been doing this a while then the comp is most likley cooked by now.
Jon
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12-09-2010, 03:12 AM #4
Re: run / start capacitor issue
You need a meter for sure. You can start "parts changing"; but that? Anyone can do.
Like Jon said, the smaller compressors have a thermal cutoff at 320 degrees. = POP! , then she cools and does it all over again,
Before you OHM a capacitor; you need to short it out. Radio Shack sells the aligator clips ( called a jumper ) at both ends of a wire, so you dont have to make one.
IF YOU OHM a capacitor,( after you short it ) even if it says "OL", it still may be good. You NEED to hold those leads on that capacitor for at least 10 seconds. At FIRST it will state "OL" and then it will give you a number, OR remain in "OL" = outa limits = BAD.
IF you have a FieldPiece meter like me, then you would KNOW for sure on your capacitors with the MFD feature of their meters.
It tells you the farids on the display, match them up with the actual cap number and the cap is good.
To SEE if your compressor is good, REMOVE the compressor from the circuit, ( pull the wires), black is common, yellow is start and RED is run.
Take your meter again on OHM and go from your common to a good ground like the high side line.
"OL" = a GOOD compressor.
ANY RESISTANCE ( a number ) = a bad compressor, what they call "gone to ground",
The same thing with the run and start to A GROUND = OL is good.
From run to common ( on the compressor ) and start to common you will get like 1.7, and 0.7. on a good compressor. Remember to do this again with the wires OFF the compressor.
A person can DROP a new compressor while carying it and that winding on the bottom MAY come in contact with the compressor shell. WHEN THIS HAPPENS, the compressor is useless; has to go back to the manufacturer. It has gone to ground.
good luck,Last edited by Deniver45; 12-09-2010 at 03:15 AM. Reason: forgot one more fact
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12-09-2010, 07:11 PM #5
Re: run / start capacitor issue
if it was of for a long time, try to warm if up whit a small blow torch. start at the bottom. Warming, not welding or overheating. when you think it is warm enough, try and start it up. when hey is warm enough and ready you can always give it a kiss whit a hammer. if it starts, take notes from the compressor, because it will not last long anymore before it will give up completely.
Ice
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13-09-2010, 12:36 AM #6
Re: run / start capacitor issue
Thanks for the replys.
i'll do some testing and see what's what.
i'm opting for the hammer option atm.
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