Forum Discussion

MKirkland's avatar
MKirkland
Explorer
Jun 15, 2015

AC question again

We are finally field testing our trailer ac this week. It is a Dometic unit that is manual for a 22 ft trailer. On high with an outside temp of 85 it starts out cold and then the air becomes like a fan but will get cold again later. The temp in the trailer fluctuates two or three degrees during this time. So it is cycling off and on. There is no thermostat that I'm aware of. I can't find a manual. I don't remember it doing this when it was new. Any ideas? Thanks.
  • SoundGuy's avatar
    SoundGuy
    Explorer
    Jun 15, 2015
    MKirkland wrote:
    There is no thermostat that I'm aware of.


    You haven't told us just which Dometic A/C you have but if it's installed as a direct blow (i.e. not ducted and no wall thermostat controlling it) then the thermostat is one of the controls on the ADB (Air Distribution Box - i.e. ceiling unit).
  • ScottG's avatar
    ScottG
    Nomad
    Jun 15, 2015
    It sounds like it's icing up.
    Make sure the filter is clean and that the sensor is still attached to the fins. You can see it after removing the filter and looking up at them. If loose, it will be dangling from its wires. Make sure the fins are clean as well.
    Also running the fan on high will help to keep it from freezing up.
    I would also go up on the roof and remove the cover. Make sure the coils up there are clean as well. There are cleaners designed for this purpose that are available at Ace HW or Home Depot but Simple green works nearly as well.

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