Short Cycle A/C

Greetings all!

I have a Sundance 3200FK with the Dometic LCD thermostat that when we set the temperature below 70 (and coincidently the outside temp is below 70) the A/C unit short cycles. By short cysle, I mean it cools to temp, compressor shuts down, delay, fan shuts down, delay, fan comes on, delay, compressor comes on.... yet the fan is set to low and the delay is measured in tens of seconds, not minutes. Odly enough, its almost normal when we cover it with a towel (delay is longer), but very bad when uncovered.

The thermostat has been replaced once, and seemed to solve the problem. But last weekend, it was back!

At higher outside outside temps it seems to run normally.

Now I'm sure most of you are thinking, "why would you set it to below 70 anyway. Well, you see my (*cough* 50 yo *cough*) wife likes it cooler at night, and thats all I'm going to say!

Thanks for any advice/ideas!

Hi John,

When temps drop, running the thermostat with fan set to LOW can create problems including icing on the coils. Not sure if it might be responsible for the cycling you're experiencing, but I'd suggest trying it out with fan set to AUTO. To change the fan mode, cycle the thermostat from COOL to FAN and use the + or - buttons to cycle the fan setting to AUTO.

danemayer said:

Hi John,

When temps drop, running the thermostat with fan set to LOW can create problems including icing on the coils. Not sure if it might be responsible for the cycling you're experiencing, but I'd suggest trying it out with fan set to AUTO. To change the fan mode, cycle the thermostat from COOL to FAN and use the + or - buttons to cycle the fan setting to AUTO.

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Thanks! That actually sounds like the problem from what I have seen on other posts. I'll give it a try in two weeks when we go out again.

That was the problem! Thank you!