ac comes on with heat unit

There are 2 different heating systems in air conditioners, some use a heating strip and just blow warm air and the other method uses reverse air conditioning where the compressor works, but remove heat from the outside air and blows the warm air into the rig. I think that is called a heat pump.

Thanks, I missed it again earlier. went back out again and noticed, fan was set on hi not auto. everything is normal again. or as close as it can be. it's a 13 heartland sundance

Is it just the A/C blower (fan) coming on...then t-stat in 'auto'

IF A/C blower & Compressor are coming on you have a shorted t-stat or A/C controller failure.

The fan mode on t-stat controls just the A/C blower.......furnace is separate and is only controlled via 'heat mode' on t-stat. You can not just turn on furnace fan without turning on furnace

x's 4 Turn the fan to auto.

MFL, you beat me to it. : )

I had this issue with a 2012 Surveyor I used to have. What kind of trailer is this? On mine I was also tripping the air conditioner breaker off to stop the air from coming on. The cure was to put the thermostat on automatic ( AU ) mode instead of Hi or Low. On that setting the air conditioner didn't come on with the furnace.

If you don't have the fan set on auto, it will do this. If set on low or high, the AC fan will run, as well as the furnace fan.

Jerry

What brand and year of fifth wheel do you have?

Are you sure it is not the heat pump coming on? Mine uses the heat pump until the temp gets to low then it switches to the furance.

If your temp is right at its changeover point when it should switchover to furnace. On mine its right around 40 degrees, They will get confused on which mode they want to run, So it will turn on the fan like the AC is on then take a little while to decide to run the heat pump or switch to or propane. What was the outside temp when you did this?, I just set my mode to furnace when the weather is going to be below 42.