Please give me some basic guidance on diagnosing home AC system. The display
on the electronic thermostat went dark, but the batteries aren't dead. The
on/off switch on the thermostat can still start the air handler in the
attic, but the outside compressor won't run. The breaker did not trip off.
There was a lightning storm. What can I do before calling the repairman?
Start by shutting off all electricity to both units at the breaker. Wait
about 15 min. and reset the breakers. See if anything changes.
You might also have someone turn on the unit while you are outside near the
outdoor unit. If you hear a clicking sound call a service person. If you
hear no sound there is probably a problem with the wiring from the inside
unit to the out....call a service man.
I am not a repairman and did not sleep at a Holiday Inn Express last night.
This did however happen to me today also.
Mine was a bad time delay on the outside unit. Ended up it was not even
needed due to my thermostat being digital. At least that's what the service
man told me : )
My guess is the storm caused the problem whatever it is.
This is Turtle.
i would take the batterys out of the thermostat for 4 hours and then replace
them with new batterys in the 4 hours later. During this 4 hours , i would also
turn the breaker off to the furnace / air handler to add another check on it
too. If after 4 hours with no high volt power and battery power. it will not
work, i would say the odds of a bad thermostat would be good but I will say
this. I can't see it from here and it could be anything.
First I would jump out the T-stat wires and see if the compressor comes
on (make sure you jump the correct wires). If it does come on, then you
know it's the T-stat.
The on/off fan switch will still work the air handler as it's just a
regular switch integrated in the T-stat.
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