[Daryles]

IF you have a late model rig with a Coleman air conditioner/heat pump rear unit on the roof, I believe in heat mode it will use the heat pump until outside temperatures reach about 40⁰F. Then it will automatically switch to furnace mode which uses propane.

The difference between heat pump mode and furnace mode is, in heat pump mode it uses shore power electricity. The air conditioner has a switching valve which makes the unit extract heat from the air and blow that into your rig. The exact opposite of how the air conditioner works.
This heat comes from your ceiling registers.

In furnace mode it uses your propane to fire the furnace to heat your rig. This heated air comes from the floor registers.

There is a furnace manual in the files section. It has a troubleshooting chart.

IF you are in furnace mode AND you have propane (check your cooktop is working) and the furnace turns on and blows air for a few seconds then turns off, it could be a sign of the sail switch having a problem.
Check YouTube for furnace troubleshooting videos.

When you change propane tanks, turn the valve on very SLOOOOOWLY!!!!
If you turn it on too quickly it has an internal safety valve which will think there's a leak and automatically shut off.