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    Gavin1234's Avatar
    Gavin1234 Posts: 1, Reputation: 1
    New Member
    		  
    #1

    Sep 12, 2009, 09:05 PM
    My Honeywell programmable thermostat RTH7400 won't turn off.
    I turn the thermostat to OFF but my a/c outdoor unit keeps running and won't stop. HELP
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #2

    Sep 13, 2009, 03:30 AM
    It is a good possibility that the problem is in the outdoor unit. There is a item called a contactor and it takes a 24 volt signal from your thermostat to activate it but many times the contactor becomes stuck due to a shorting of the power contacts and that causes the outdoor unit to stay running even with the thrmostat turned to the off position. I suggest you kill the power to the outside unit until it is repaired. It looks like these
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