RV Repair: hydro flame model 8531-11, hydro flame, 12 volt

Question
hi Bill i have a 1994 savanna by Fleetwood trailer with a hydro flame model # 8531-11 furnace. when the thermostat is turned off the fan will just come on, there is no specific time that it happens it could be an hour or minutes after i thought that it mite be the thermostat so i installed a new digital one but it still does it. it does it on 12 v and 110v . please help me if you can thank you Leon

Answer
Leon, What kind of air conditioner does it have? If it is a dometic you will want to check to see that the control unit is good. Try disconnecting the 2 wires to the furnace from the T-Stat and see what happens then. If it stays off then something is touching one of the wires that goes to the T-Stat. If you can get to the back of the furnace you might want to disconnect one of the 2 blue wires going to the furnace. The furnace runs on 12 volt only unless this is a park model then the fan motor could run on 110 vac. Otherwise it is all 12 volt that runs them. The only way they can come on is for power to get from 1 blue wire to the other and no other way. Thanks, Bill