Need help/info re furnace thermostat

[Lane]

Couldn't find this in a thread & could use help. I have a 2017 Airstream Interstate bought in April. A/C works great but just tried heat, & when choosing 'furnace' on digital thermostat and setting the temp, it begins by running the roof A/C and the floor furnace (propane) at the same time. After a few seconds I can turn off the A/C (click 'off' twice & the roof A/C will stop), but heat, which has gotten warm and working, finishes its cycle and stops about a minute after the A/C stops. Pretty self-defeating because the roof A/C puts out as much cold air as the furnace puts out warm air. I've never had a digital thermostat before, but how else would I turn it on other than clicking 'furnace'? ALL help appreciated! Headed to the mountains for Christmas and very worried.

[hbn7hj]

Look up the manual for the thermostat. If it is Dometic hold the mode and temp up buttons down together til two dashes appear on the display for reset.

They lose their minds sometimes.

[Lane]

Thanks.
Turns out we had the fan on 'low' and that was the problem. When we changed it to 'auto' it let the furnace take over without the A/C. Go figure.