Furnace Burner Cycling at startup
My 2016 Montana High Country has an Atwood/Dometic furnace, model AFMD35131-A. Whenever I turn the furnace on (or it comes on based upon the thermostat setting), the burner will cycle on and off seve...
Forum Discussion
Sounds like it is operating off of the 'high temp' switch---called 'limiting'
Temp comes up to fast a rate of increase..furnace overfiring...high temp switch opens shutting down DC to circuit board. Fan continues to run...high temp switch cools/closes/DC back to circuit board/t-stat still calling for heat so burner fires.....cycle repeats
Causes:
Blocked ducts, too many registers closed/obstructed ----resists air flow
Restricted return air -----minimizes amount of air back to furnace
LP System Pressure.......too much fuel/overfiring
Defective high temp limit switch.....190*F switch #31091
If you remove outside access panel you should be able to see the LED on the circuit board
1-Flash with 3 second pause.......Limit switch/airflow issue
AFM Series Furnace
Temp comes up to fast a rate of increase..furnace overfiring...high temp switch opens shutting down DC to circuit board. Fan continues to run...high temp switch cools/closes/DC back to circuit board/t-stat still calling for heat so burner fires.....cycle repeats
Causes:
Blocked ducts, too many registers closed/obstructed ----resists air flow
Restricted return air -----minimizes amount of air back to furnace
LP System Pressure.......too much fuel/overfiring
Defective high temp limit switch.....190*F switch #31091
If you remove outside access panel you should be able to see the LED on the circuit board
1-Flash with 3 second pause.......Limit switch/airflow issue
AFM Series Furnace
