Reset the temperature selector on the thermostat to the desired position if the furnace blower fails to run. The temperature selector may have been moved out of place. If the temperature selector is too low, the furnace blower will not run. If this does not resolve the problem, check the RV circuit breaker for a tripped circuit. Confirm that there are not too many electronics drawing power from the circuit, and reset the circuit.
Listen to the motor for any indication that it is running slower than normal if the blower runs but fails to ignite. An indication of a slower motor will be evident in the audible tempo or rhythm of its cycles being slower than normal operation. Also check the voltage of the furnace motor with a voltmeter. If the motor only produces 12 VDC or less while running, replace the motor with a new one.
Clean the burner head located near the furnace body with a wire brush. An obstructed burner head can sometimes cause a failure to ignite while the blower is running. An elongated wire brush will make the burner head more accessible.
