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-   -   Compressor starts when cool, not when haot (http://forum.appliancepartspros.com/refrigerator-freezer-repair/502102-compressor-starts-when-cool-not-when-haot.html)

c893 10-04-2012 02:03 PM

Compressor starts when cool, not when haot
 
My french door fridge stopped cooling. When the compressor itself is allowed to cool, it will start and cool the fridge to specified temps and shut off, as it should. Later, when the warm/hot compressor tries to come on again, the relay buzzes, and the compressor will not start. If unplugged and allowed to cool again, the compressor will start.... I have replaced the relay unit - no change. I know the compressor failing is the likely trouble, any other possible causes for a short-cycling compressor? Is it possible the compressor is being asked to come on too frequently? What would cause that? The defrost circuit tests OK (all the tests when the unit is in service mode look OK). I'm hoping because the compressor runs, it's something else causing the problem. Am I dreaming? What to test next?

Simon / APP Team 10-04-2012 04:25 PM

Hi.

Most likely the start winding in the compressor is damaged and fails when it's hot.

Simon.

c893 10-04-2012 05:18 PM

My ohm meter gave me readings of 5.9 start to common, 4.7 run to common, and 10 run to start. That seemed OK to me. What do you think?

Simon / APP Team 10-04-2012 05:26 PM

As I said possibly the start winding fails when it's hot.
Simple ohming may not be enough to determine it.
If the current draw is grater then listed on the compressor then it's bad.

Simon.

c893 10-04-2012 06:12 PM

Could it be a sealed system restriction? That's not something I could test, but how is that usually checked?

richappy 10-05-2012 02:44 AM

Check the freezer and fridg temperatures after it's cooling well, should be around 5 degrees for freezer and 41 degrees for fridg.

c893 10-05-2012 08:23 AM

When cool the compressor starts every time and takes the fridge/freezer to operating temps (38 and 0), which, after reading your post, I confirmed with a second thermometer and not just with the fridge’s own display. It’s restarting to maintain the temps where the problem arises. Today I noted when the fridge/freezer reached the proper temperatures and listened for the compressor to shut off. It shut off about 30 minutes after the freezer digital temp was 0 and right about exactly when the secondary thermometer reached zero. 15 minutes later, without ever opening a door, the compressor tried to come on again, the relay buzzed and the compressor did not start. About 60-90 seconds later it tried again. And 60-90 seconds again.... Then I shut if off. It seems like the compressor is being asked to come on too soon/often. We have frequent power interruptions in my area, could this have taken a toll on the main board (I see no physical damage on it)?


The compressor doesn’t cool enough to start before being asked to come on again. Frustrating.

richappy 10-05-2012 04:28 PM

It is possible the compressor is overheating due to low refrigerant. Gauges and amprobe would confirm. If the compressor seems to be running longer than normal, that would confirm it.
If you cool the compressor with a portable fan and it no longer fails to start, that would confirm low refrigerant, or a bad compressor/clogged condenser. A partially clogged capillary would do the same thing, but the compressor current would be lower than normal.

c893 10-05-2012 05:06 PM

Well, none of that sounds too good. Would those things also make the compressor come back on so quickly after cooling the fridge and freezer down to their preset levels?

richappy 10-06-2012 01:43 AM

No, not at all. The control module controls the hysteresis ( differential between turn off/ turn on temperature levels).
Also, it is possible the thermistor is cracked and off value. I would replace both.


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