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Heating, Air Conditioning, Fridge, HVAC/Air Conditioner Fan will not shut off automatically


QUESTION: Hello there.  We live in Canada and have a problem with our AC unit which is outside of our house.  2 weeks ago it was still cold here but we went outside to check out the Winter damage.  The AC unit's tarp that covers it had blown away, and the fan was running - even though the air inside the home was warming as usual by the thermostat.  There was a build up of dust around the unit and I turned off the A/AC at the breaker.  The installer advised me to simply hose the outside of the unit gently then turn on the A/c to see if it works as it should do.  Today it is 30 degrees and we put the A/c on.  Everything came on fine, but when we turned the switch off at the thermostat - the fan outside is still going.  Again, we have just had to turn it off at the breaker.  Any ideas what's going wrong?  The unit is only about 2 years old.  Thank you..

When the thermostat calls for cooling it sends electric power 24 volts to switch/relay that turns the fan and the compressor on that is in the outside unit.
I think that some place along the way from the thermostat to the outside units switch there is a short or a control stuck in the on position.
You can check the low voltage wires that run along with the copper refrigeration lines that go from the inside unit to the outside unit for breakes or being chewed by animals/ varments?

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QUESTION: Hello Jim, sorry to bother you again and hope you can help further!  We looked at the outside wiring and the wiring inside (we don't have a unit specifically for the AC inside) the A/C is operated by our house thermostat.  It doesn't appear as if anything has been damaged or broken.  We turned the unit on to heat today to see if it would switch off the AC fan outside, but it's still going strong!  We are going to switch it off again at the breaker panel in the basement.  Is it time to call the service people???

Kay Manuel

I'm assuming that you have a split system which means a unit inside that has a blower and some un-disclosed heating apparatus, gas or electric and a cooling coil?
Plus an outside condensing unit for cooling the coil that's in the inside unit.
When you set the thermostat to cool and set the indicator to a low enough temperature the thermostat sends 24 volts of electricity out side to a switch in the condensing unit that turns the compressor and the fan on and they both run.
When the thermostat setting gets satisfied it turn the 24 volt power to the outside unit off which turns the switch off and the compressor and fan both stop.
You could have a faulty thermostat, a shorted wire, a stuck on outside switch, a faulty switch.
If you or a person you know who is mechanically inclined isn't available you need to call a service company,
Try to look over the shoulder off any repair person so they don't sabotage your unit and try to sell you something you don't need?

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Jim Barnhart


Fifty + years conditioning the air.


Answer questions about , residential and commercial. Answer questions about sheet metal fabrication. Fifty years plus experience. No answers for oil equipment, No answers for kitchen appliances, No answers for laundry appliances, I don't specialize in one particular area of the HVAC area, I'm more of a General Practitioner, Limited in refrigeration/

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