Central AC won't shut off, runs continuously

davefrommdOctober 23, 2007

Our central air conditioner keeps on running and won't shut off. I had to remove the fuse outside to stop the outside fan from running constantly. I don't have the model number at this moment however can get it tomorrow. It is about a 10 year old electric carrier AC for a 2 story house 30'x50'. It would not shut off at the thermostat so I replaced the old thermostat with a new one today. Last year a capaciter had to be replaced in the unit outside. The air handler is up in the attic. Any suggestions as to how I can fix it or what to look for would be greatly appreciated. Thanks in advance. dave

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Sounds like a stuck contactor or short in thermostat (low voltage) wire. If you remove access plate on outdoor unit, you should be able to get at contactor to see if it's stuck. BE SURE ALL CURRENT IS OFF BEFORE TOUCHING ANYTHING IN UNIT!!!

    Bookmark   October 23, 2007 at 9:46AM
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The air conditioner is a Carrier Tech 2000 ss Silencer System High efficiency Air Conditioner. dave

    Bookmark   October 23, 2007 at 9:48AM
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I appreciate your help greatly. Yes I have the fuse removed outside and will also turn off the AC circuit breaker at the fuse panel. Thanks again. dave

    Bookmark   October 23, 2007 at 9:29PM
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I don't know how I ended up with two of the same postings however the help has been great. Thanks. dave

    Bookmark   October 24, 2007 at 11:33PM
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either you have a short in the wiring, or your contactor is bad. unplug the wire to the side of the contactor if the unit stops you need to find the short in the wiring to the thermostat. A very common problem...

    Bookmark   October 26, 2007 at 12:55PM
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I looked at the contactor today and it was stuck on. I had the power shut off and tested for voltage. Then I just touched the plastic part of the contactor where the spring is with an insulated tool and it got unstuck. I will replace the contactor with a new one and my AC will be fixed. I greatly appreciate the good help I received on this forum. Thanks again. dave

    Bookmark   November 1, 2007 at 11:19PM
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I replaced the transformer and now my ac wont shut off.

    Bookmark   August 1, 2011 at 8:38PM
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