Before I call the pros, I am going to do some basic troubleshooting on my
central AC. The fan and compressor are not coming on. I can hear a
low-voltage hum. I will start with a meter to make sure 220v is getting to
the contactor and also 220v is coming out of the contactor.
Since I don't have any experience with 220v, I would prefer to not belt
myself. Out of the wall is a pink and black wire to the contactor. Where
do I put the meter leads to test it? Any danger moving the leads from
terminal to terminal as long as I don't hold the leads by the metal end
(just kidding). Also, when the unit comes on, should I see the contactor
move, or click, or what?? I didn't see anything like that, so I am thinking
220v is not getting to the unit.
Thanks for your time.
If you have someone turn the thermostat up and down, you will hear the
contactor click in and drop out. It operates on 24 volts which it gets from
the blower unit. Near the condenser should be a disconnect. open the
disconnect and find the two terminals marked "line". If you touch the
terminals of a meter across these two terminals you should get 240 volts. If
not, check the breaker feeding the condenser
OK, this is going to sound nuts...The contactor was not clicking on. Out of
frustration, I banged the side of the unit (like whacking the side of a TV),
and the unit kicked on. Holy smokes...there seem to be no loose wires, so
my thinking is the contactor is bad. I think I will replace it. Any other
ideas? I don't have a magic touch.
My whole system is from 1979, not "modern" I would think.
Yet neither the heat nor the AC go on for 2 or 3 minutes after I turn
it on at the thermostat, or at the power switch on the basement wall.
Is that the same short-cycle protection?
I have a Carrier AC and maybe a Carrier furnace too.
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