ServiceNomad RV · Knowledge
RV Furnace Blowing Cold Air
If the furnace runs but the air coming out is cold, the burner is not lit. The system typically runs the fan for 30-90 seconds to purge the chamber before shutting down if ignition fails.
Sail Switch Failure
The 'sail switch' detects airflow. If the battery is low and the fan runs slow, or if the switch is stuck with lint/dust, it won't tell the control board to open the gas valve. The fan runs, but no fire ever starts.
Control Board Lockout
After 3 failed attempts to light, most furnace boards go into 'lockout' mode. You must turn the thermostat to OFF for 30 seconds and then back ON to reset the board and try again.
Low Voltage
RV furnaces are power hungry. If your battery voltage is below 11.5V, the fan may spin but not fast enough to engage the safety sail switch, preventing the burner from lighting.
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