Symptoms
- Furnace fan doesn't run at all when the thermostat calls for heat
- Fan runs but no heat comes out
- Furnace tries to ignite but shuts off repeatedly
Likely causes
- CommonLow 12V battery voltageRV furnaces rely on 12V power for the blower fan and ignition control even though the heat itself comes from propane.
- CommonPropane supply issue (empty tank, closed valve, air in line)Since the furnace burns propane, any supply issue affects it just like other propane appliances.
- PossibleBlocked exterior intake/exhaust ventDebris, snow, or a nest blocking the furnace's exterior vent can trigger a safety shutdown.
- PossibleFailed igniter or circuit boardAfter basic power and fuel checks, a failed ignition component is a common next step for a furnace that tries but won't stay lit.
What to do
- Check house battery voltage and connect to shore power or run the generator if it's low, since a weak battery is a very common furnace no-start cause.
- Confirm the propane tank has fuel and the valve is open, and check that another propane appliance works to rule out a supply-wide issue.
- Inspect the furnace's exterior vent (usually a small grille on the RV's exterior) for blockage from debris, insects, or snow.
- Check the thermostat settings and batteries (if it uses its own batteries) to confirm it's actually calling for heat.
- Listen for the furnace attempting to ignite; repeated clicking without lighting suggests an ignition or gas supply issue rather than a fan problem.
- If battery, propane, and vents all check out, the furnace's igniter or control board likely needs professional diagnosis.
Tools and parts
- Multimeter
- Flashlight
Furnace igniter or control board, model-specificSearch: “RV furnace parts for [your furnace brand/model]”
When to call a pro
For ignition or control board failures, have an RV or propane appliance technician diagnose and repair the furnace.
Safety
Use caution
If you smell gas or the furnace repeatedly tries to ignite without success, turn off the propane supply and have a technician inspect it rather than continuing to try.