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RV_Sam's avatar
RV_Sam
Explorer
Jul 20, 2015

Dometic Duo Them air conditioner

Hi Guys. I have a Dometic Duo Them air conditioner in a 36 foot Sprinter. Not sure of model or size, sorry. Auto/On set to ON. Fan runs. Flip the Cool/Off/Furnace over to Cool and the compressor kicks it. In a few minutes the air is cold from the unit. Temp in trailer is 80 deg. Thermostat set at 70 deg. All is cool for around 5 minutes, then the fan speed drops, unit shakes, and the compressor kicks off and fan goes back to full speed. Stays like this for a minute or two and the compressor kicks back in with no strain, blows cold air for a few minutes and repeats as above. Fan speed set to Low or High, no difference.
Thanks for any things to check on.
  • RV_Sam's avatar
    RV_Sam
    Explorer
    Jul 21, 2015
    Will take a look. I don't think it'll ice in a few minutes though. Thanks.
    Anyone have any thoughts on maybe the run cap. The shaking makes me think like the motor is trying to reverse, which I know is not possible, but thinking the cap is involved somehow ???? Thanks.
  • time2roll's avatar
    time2roll
    Nomad
    Jul 21, 2015
    I can describe my Dometic. The interior trim has an inlet filter and a direct vent for cold air to come down direct or close the vent to have cold air come through the ducting in the ceiling.

    When you remove the interior trim there is a metal plate that separates the inlet from the outlet. My divider was poorly placed and poorly taped. This allowed much of the chilled air to immediately return into the machine.

    I did this fix while in CO returning from NE. The unit was freezing up.

    Assuming you have a wall thermostat you should have a freeze sensor that often falls away from the evaporator and fails to sense the ice up.

    Give it a look.
  • RV_Sam's avatar
    RV_Sam
    Explorer
    Jul 20, 2015
    smkettner wrote:
    Yes remove the lower trim and inspect the plenum divider.

    What is it I am looking for once removed please.
    Not on long enough to make ice. ( I don't think so )
    The day before it worked perfectly.
    And for the few minutes that the compressor is running each time, nice cold air, just does not stay on long enough to do any good.
    Thank you.
  • dougrainer's avatar
    dougrainer
    Nomad
    Jul 20, 2015
    imgoin4it wrote:
    Sounds like coils are freezing up. Compressor shuts off and when thaws out, kicks back in. One of my two does same periodically and I'm not sure what to do to"fix".


    Not going to freeze up in 5 minutes, even 30 minutes. I will bet he has a bad compressor. He needs to monitor the compressor amp draw and if it goes over 15 amps, his compressor is bad. Doug
  • TInmania's avatar
    TInmania
    Explorer
    Jul 20, 2015
    If it is freezing up it might be due to cold air bleeding back into the return line. High humidity exacerbates the issue.



    Mike
  • imgoin4it's avatar
    imgoin4it
    Explorer
    Jul 20, 2015
    Sounds like coils are freezing up. Compressor shuts off and when thaws out, kicks back in. One of my two does same periodically and I'm not sure what to do to"fix".

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