Outside A/C won't stop running

[dubell]

Hello all. I have a friend whose outside a/c unit won't stop running. His thermostat is set to auto for the fan, and off for the heat/cool. It has been running continuously since December.

What does this sound like?

[rabadger]

Contactor is stuck or you still are getting 24 volts to the contactor coil.

[dubell]

Don't know what a contactor is. I assume this is in the thermostat? Is there a contactor just for the outside a/c unit, bacause nothing else is running.

Thanks,

Doug

[Cole]

Don't know what a contactor is.
Dont worry neither do I, but I am sure Richard will explain it us.

[roger g]

Do you know what is actually running outside? Is it the compressor and fan or just fan and or just compressor? If you follow the high voltage wires into the outside unit thet will go directlt into a hard plastic black box. The big wires may go through a big shut off switsh first before going into the unit.On the other side of that black box you will see the same heavy wires leaving the black box and some other smaller wires leaving it also. That black box is the contactor. There are some small wires also going into the condensor ( that's the thing outside we are talking about) and they also will attach usually to the side of the black box. When the T stat calls for cooling it send the message down to the furnace then out to the condensor and into the contactor which energizes it and it closes and makes CONTACT so the power goes from the house through the contactor into the compressor and fan. When the house is cool enough the CONTACTOR opens and the compressor and fan is supposed to shut off.


roger

[rabadger]

December? Where does he live? Is this an air conditioner or heat pump?

[Sparks]

Just tell him to shut off the disconnect, usually attached to the house, or just shut off the breaker, and then call an HVAC contractor to replace defective contactor or shorted stat (unlikely in my experience).

[rabadger]

Sparks is right, shut it down and call the fix it guy.

[dubell]

yeah, it's time for a call.

Thanks guys,

Doug