Furnace keeps shutting off, fan keeps blowing
2018 fifth wheel, ducted furnace with ducts under the floor. 30A shore
Customer says: The furnace lights and heats for a few minutes, then the flame goes out and the fan keeps blowing. Then it lights again.
Bedroom registers blow hard. The living room registers barely blow.
Tests you can run
- 12V at the furnace with the blower running
- Watch a full cycle at the furnace
- Air temperature at the furnace outlet
- Check every register and the return
- Look at the ducts under the floor
- Ohms on the high limit switch while it's cool
- Replace the high limit switch
- Jumper the high limit so the burner keeps running
Repair options
Keep going on furnaces
Learn it
Prove it
- Furnace blows cold
- Furnace sparks but never lights
- Thermostat clicks, furnace does nothing
- Comeback: furnace quits again