Why does our home AC cycle on & off so quickly?
Question:We can hear the thermostat/ac unit trying to start up then it shuts down. We turned off the breaker but the fan is still running. Outside unit sounds fine. Is it the thermostat?
Answers:
If it still does the same thing when you turn the thermostat down some... it's probably not the thermostat... A bad thermostat would tend to not switch the unit on at all or lose it's ability to sense temperature changes well. Sounds like your thermostat is switching the AC on like it's supposed to. It would be very unlikely for your thermostat to switch back into the off position by itself, espicially if it were set considerably colder than the room temp.
Most likely the compressor is not starting or it's quickly overheating and shutting down. Could be anything from evaporator coils needing cleaning, bad cooling fan, bad starting circuitry for the compressor... to a bad compressor. If the compressor is seized, stuck or otherwise unable to start... You'll hear a buzz or hum while it tries to start... then it will quit. If the compressor is actually starting and overheating (or a bad thermostat / connection is turning it off)... You'd likely feel a little colder air starting to come out of the vents until it cuts out.
If it was low on refrigerant... it would run normally... just wouldn't cool the air...
Yes, you could have a faulity thermostat or your unit could be low on freon.
There is also a cycling switch may cause it. by turning off the breaker, everything should shut down including the fan, sounds like you have a short.
Short cycling is often caused by OVERSIZED air conditioners. For example, if you have an 1600 sq. ft house and the central air is sized at 3 1/2 Tons it is much to big and will turn off and on frequently and will not remove the humidity from the house.
Unfortunately you did not provide the size of the house or the size of the central a/c unit so I can't offer any more recommendations.
You might want to contact an HVAC company and have them check size of the a/c unit and do a heat/cooling alalysis on the house to determine propere sizes.
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