Atwood 8531 RV Furnace Cycling

Learn more about lennox furnace repair here. The furnace blower cycles after shutdown. Will not stop. Have to turn off power at the switch on the blower housing. Replaced the the circuit board, and limit switch so far. When the furnace is running. No Fault light. When shutdown. Fault light comes on. 1 flash every 3 seconds.The furnace is not that noisy. Runs pretty quite. Open for answers.