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bholt's avatar
bholt
Explorer
May 24, 2014

Thermostat Blowing 2 Amp Fuse

I have a 2000 Wilderness which I acquired a year or two ago, it has been taken excellent care of. I keep the trailer at my lease and leave it plugged in however the only thing drawing power is the light on the microwave. Last weekend while there I went to turn the fan on and nothing happened, no fan or humming as if the fan was bound up. Looked at the thermostat and the 2 amp fuse was blown. This is one of the small 3/4" glass fuse that came with the Coleman Mach analog (thermostat original equipment). I plugged in a 110 volt fan and ran it that night it worked fine along with the other 110 circuits and 12 volt lights. The next day I crawled up on top and checked the fan motor, it was not bound up, so I also confirmed the heater motor was free. I went into town and purchased 2 fuses, at the automotive store. Since they did not have any 2 amp I bought 3 amp fuses. When I got home I replaced the fuse and it blew. Before I left I tried the last one. This time I took note of all the switch positions. The heat/cool/fan switch was in the off position, the fan switch was in the high position but set to about 85 degrees. I still had the electric fan running on the 11o circuit. I went to install the fuse it immediately blew and the electric fan seemed to go to slow down. I did check the voltage on the 110 later but by then it was back up to 110. I am thinking I have a short some where but I am concerned about pulling the wires through the wall and ceiling to the AC. ANY IDEAS?
  • Clearwaterpaul's avatar
    Clearwaterpaul
    Explorer
    Aug 07, 2017
    Thank you for your comments so far.

    I'm having the same problem.
    Timeline:
    2007 Fourwinds Windsport
    AC in the bedroom.
    Fuse blows.
    I replace.
    Fuse blows.
    I replace.
    Fuse blows.
    I replace but have to squeeze the fuse holder because it was loose, I hit the board with the pair of pliers and blew the board.
    I got a new thermostat, the new one that replaces the older model.
    Fuse blows.
    I replace, no problem for a while and then blow.
    I replace.
    It blows again.
    It blows immediately now.

    I checked all of the connections and it seemed to work longer but it still blows.
    To check any wires beside these will be one heck of a chore (taking down walls)

    What next?

    Paul
  • dougrainer's avatar
    dougrainer
    Nomad
    May 26, 2014
    The fuse is on the 12 volt control circuit for the Roof Top AC. Has NOTHING to do with your 120 voltage at the AC or anywhere else in the RV. As the other poster stated, you have a short between the wall tstat and the roof AC control board, OR, possibly between the Wall tstat and the LP furnace. BOTH appliances rely on the wall tstat. Doug
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    May 24, 2014
    You have a short in thermostat wiring or in the control circuit wiring

    Could be on 12V DC wire to t-stat from battery (RED)
    Could be on 12V DC wire from t-stat to furnace (WHITE)
    Could be on 12V DC wire from t-stat to AC control (Yellow)
    Could be internal short t-stat

    First place to start....remove t-stat and inspect for burnt contacts/loose wiring/wires touching

    Here is a service manual for your t-stat........LINK

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