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Old 06-02-2008, 07:36 PM   #1
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outside unit help


Have a problum with outside unit. can't get it to turn off, will oonly stop by turning off breaker what should I do and to what.
raskgle is offline   Reply With Quote
Old 06-02-2008, 09:41 PM   #2
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outside unit help


If this is a split system, meaning that there's an indoor air handler unit and an outdoor compressor/condenser unit, then most likely there's a contactor inside the outdoor unit. This contactor turns the compressor and condenser fan on and off. It's controlled by the indoor unit. There are 2 possibilities that I can see.

1) The contacts of this contactor have welded themselves together. In other words, it's always on, even if the indoor unit tells it to be off.

2) This contactor is controlled by the indoor unit, and for whatever reason it's being told to stay on always.

It's actually pretty simple and totally safe to determine where the problem is; first, with the indoor unit powered up, and the outdoor unit powered down (circuit breaker off) turn the 'fan' switch at the thermostat to 'on'. Make sure that the indoor fan is actually running. Next, find the breaker that feeds the indoor unit and turn it off. Make sure that the indoor fan stops. Now (this might take 2 people) turn the outdoor unit breaker on, but just for a second. Be careful here, depending on what type of expansion valve you have, running the compressor for more than a few seconds with the indoor unit de-powered can damage the compressor.

If the compressor starts with the indoor unit de-powered, the contactor is bad (welded closed). If it doesn't, then you have either a bad thermostat, a short in the thermostat wiring, or something in the indoor unit (like a control board) has gone bad.

Rob
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Old 06-03-2008, 01:59 PM   #3
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outside unit help


Thanks I will try this. you said the good simple check.
Quote:
Originally Posted by micromind View Post
If this is a split system, meaning that there's an indoor air handler unit and an outdoor compressor/condenser unit, then most likely there's a contactor inside the outdoor unit. This contactor turns the compressor and condenser fan on and off. It's controlled by the indoor unit. There are 2 possibilities that I can see.

1) The contacts of this contactor have welded themselves together. In other words, it's always on, even if the indoor unit tells it to be off.

2) This contactor is controlled by the indoor unit, and for whatever reason it's being told to stay on always.

It's actually pretty simple and totally safe to determine where the problem is; first, with the indoor unit powered up, and the outdoor unit powered down (circuit breaker off) turn the 'fan' switch at the thermostat to 'on'. Make sure that the indoor fan is actually running. Next, find the breaker that feeds the indoor unit and turn it off. Make sure that the indoor fan stops. Now (this might take 2 people) turn the outdoor unit breaker on, but just for a second. Be careful here, depending on what type of expansion valve you have, running the compressor for more than a few seconds with the indoor unit de-powered can damage the compressor.

If the compressor starts with the indoor unit de-powered, the contactor is bad (welded closed). If it doesn't, then you have either a bad thermostat, a short in the thermostat wiring, or something in the indoor unit (like a control board) has gone bad.

Rob
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