So we live in NY and are headed to FW in 12 days so of course we need to get the RV open. I checked everything and all is well except for the A/C.We use a digital Dometic 3 step thermostat. "Fan" runs air just through the A/C. "Cool" runs the A/C. But when I turn on "Heat", the furnace and the A/C come on now. This has never happened before and we used the furnace several times last fall.Any ideas? I dont know where to start. Maybe replace the thermostat?

Set the fan to auto, then set to heat.Jerry

2oldman wrote:Where is FW?Texas if it's Fort Worth.

2oldman wrote:Where is FW?Or Florida if it's Fort Wilderness.

Awkward Heat - A/C issue | Good Sam Community

dougrainer
Nomad
Apr 12, 2018
If he does a RESET, he will still have the same problem. As other posters have told him, PUT the Fan in AUTO. That is what is in the owners manual for this tstat model. Doug
time2roll
Nomad
Apr 12, 2018
esfd243 wrote:
We use a digital Dometic 3 step thermostat.
Is that the square single zone thermostat?

Reset:

A system initialization will need to be performed by the installer
after the system is installed.
• Make sure the Single Zone LCD thermostat is in the Off condition.
• Press the “+” button and, while holding it, also press and hold
the On/Off Mode button for three seconds. LCD will show - - . Press the On/Off Mode button again to turn system off.
This completes the initialization.

Dometic themostat manual
wnjj
Explorer II
Apr 12, 2018
2oldman wrote:
Where is FW?

Or Florida if it's Fort Wilderness.
TakingThe5th
Explorer
Apr 12, 2018
2oldman wrote:
Where is FW?

Texas if it's Fort Worth.
2oldman
Explorer II
Apr 12, 2018
Where is FW?
MFL
Nomad II
Apr 11, 2018
Set the fan to auto, then set to heat.

Jerry
LadyRVer
Explorer II
Apr 11, 2018
Try setting fan to automatic.