Forum Discussion

clotus's avatar
clotus
Explorer
Dec 24, 2017

AC turns on with furnace

So here is a head-scratcher that I discovered on my 3-year old 5er:

When on shore power and I turn my furnace on the AC also turns on. The AC does not have a heat strip. I would imagine the problem has been like that since new because we always use space heaters instead of the furnace when on shore power. Welp one day we forgot the space heaters and bam the AC fan turned on with the furnace.

Is this normal? I remedied the issue by simply flipping the AC breaker. Thoughts on how to fix?
  • MFL's avatar
    MFL
    Nomad II
    Dec 24, 2017
    Fan setting on auto...no AC fan when on heat. The AC fan will help distribute heat when fan set to low/high, but not needed, IMO.

    Jerry
  • Chad_Heiser's avatar
    Chad_Heiser
    Explorer
    Dec 24, 2017
    What the previous posters said. Set the AC fan to Auto and it will not come on with the heater/furnace. If the AC fan is set to low or high it will come on when the furnace is on.
  • azdryheat's avatar
    azdryheat
    Explorer
    Dec 25, 2017
    Mine came on once. The thermostat was set to AUTO and the a/c and furnace came on at the same time. Now I put it on COOL for a/c and HEAT for furnace and haven't had any issues.
  • Earl_E's avatar
    Earl_E
    Explorer
    Dec 25, 2017
    Same answer as others. Make sure fan is on auto, not low of high.
  • Me_Again's avatar
    Me_Again
    Explorer III
    Dec 25, 2017
    The new Dometic T-stat's are one of the most frustrating gadgets ever installed in a RV. Operational course is three semesters for three years.
    101,102,103,201,202,203,301,302 and 303.

    Follow the advice of the posters above.

    Chris
  • Turn_Key's avatar
    Turn_Key
    Explorer
    Dec 25, 2017
    Mine will do the same thing, depending on how I set the thermostat. Has to do with reducing humidity in the trailer, I believe. Don't recall how I set the thermostat to avoid having the AC coming on but know that I can do this. Check your Owner's Manual and it should tell you how to set it.

    PS: I believe setting fan on "Auto" is the correct answer but not sure without looking.

    Happy Camping!
  • clotus's avatar
    clotus
    Explorer
    Dec 26, 2017
    Thanks guys. I will have to look into it. The thermostat is a two button scroll system and in my opinion..... pretty weak.

    This place rocks. Happy camping!

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