Front A/C is coming on with front furnace

[jwc55]

Hello All
Just came back from a great trip in Michigan. The last night away was rather cool so we put the front furnace on to warm things up. The furnace came on like it should but so did the front A/C unit. Counterproductive to say the least. The same switch on the wall controls both the A/C and the furnace with a digital temperature setting. All units are Dometic in a 2015 Georgetown 377 XL. Bad or dirty connections at the wall switch, maybe. Any HVAC experts out there?

[Mr. Dan]

If it’s the thermostat many of us have, the A/C compressor is not coming on - just the A/C blower. Cycle through mode and stop at Fan, use + or - key to cycle fan speed from HI or LO to AU for auto.

[jwc55]

Thanks Mr. Dan. I'll give that a try.

[Dan_Frisbie]

My front A/C is a heat pump. It will try to heat up the RV and the propane furnace will kick on if necessary.

[jwc55]

Originally Posted by Mr. Dan

If it’s the thermostat many of us have, the A/C compressor is not coming on - just the A/C blower. Cycle through mode and stop at Fan, use + or - key to cycle fan speed from HI or LO to AU for auto.

Thanks Mr. Dan
It was a perfect fix exactly as you described.

[LittleBill]

Originally Posted by jwc55

Thanks Mr. Dan
It was a perfect fix exactly as you described.

I have found that if you set the fan speed to a HI, MED or LO setting, the A/C unit will run continuously whether the furnace kicks in or not. This will just circulate the air in your unit and not engage your compressor like Mr. Dan already pointed out. So you need to set the fan to Auto and then the A/C blower won't run and the furnace blower will come when the furnace will actually be running.

If you have a Heat Pump then your thermostat probably has an Auto mode which will maintain a specific temperature (within a couple of degrees) using the A/C-HP unit based on whether you need to lower the temperature or raise it.

Good luck and be safe -