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Air conditioner short cycling

July 09, 2019, 09:49:45 pm

One of my AC units is short cycling. If the set temperature is well below room temperature, it works fine, running continuously until the temp is where I want it.

After that, when the room temp is only slightly above set temp, it short cycles repeatedly. It runs for a few seconds, then shuts down. Some minutes later, it tries again. Repeating over and over until I change the thermostat set point or turn it off.

What gives?

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Re: Air conditioner short cycliny

Reply #1 – July 09, 2019, 10:37:27 pm

Vent pointed at the temperature sensor?
Thermostat delta temperature to low? E.g. 2 degrees hysteresis.
Defective AC controller PC board?
Low 12VDC voltage?

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Re: Air conditioner short cycliny

Reply #2 – July 09, 2019, 11:00:55 pm

How do you set the thermostat hysteresis ?

Vents are not pointed at the sensor.

12 volts is fine everywhere else

I hope use not the pcb.

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Re: Air conditioner short cycliny

Reply #3 – July 09, 2019, 11:35:20 pm

Sounds like somebody took out or adjusted the time delay relay. Relay is there to let head pressure bleed off between cycles. Are both units doing this? I think your in or near Alaska where ambient temperature is lower. Hope fully they just jumpered it out.

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Re: Air conditioner short cycliny

Reply #4 – July 10, 2019, 12:06:23 am

The time delay relay seems to be working. That explains the wait before it cycles again.

I'm thinking it's either the hysteresis adjustment or a bad electrical contact on the thermostat wiring.

Or the control board.

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Re: Air conditioner short cycling

Reply #5 – July 11, 2019, 01:42:25 am

It might be easier to replace the thermostat than troubleshoot the issue.   
Has the thermostat has been in the same location for a long time?  pc
 

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