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RobWNY's avatar
RobWNY
Explorer
Jul 09, 2018

Dometic Air Conditioner Stops Working

I've read many of the other threads about the coils icing up on these air conditioners and the reasons for it and I am to blame for running the fan on Low when it was hot and humid. Likely my unit froze up and I won't make that mistake again. But does this cause the unit to stop altogether? I woke up at 1am as I had gotten quite warm. I noticed that I couldn't hear the air conditioner and got up to see what had happened. The fan wasn't running like there was no power. No breaker was tripped and when I switched the unit from Low Fan to Auto and raised the thermostat a couple of degrees, it started again. Do the coil freeze ups cause the unit to completely shut off? In my old RV, the compressor wouldn't cycle but the fan kept working. Or do I have a problem that I thought was frozen coils but is something else?
  • RobWNY's avatar
    RobWNY
    Explorer
    Jul 10, 2018
    SoundGuy wrote:
    RobWNY wrote:
    I think I'll just leave it alone for now but make sure I have the fan on High or Auto if the weather is very hot and humid. I'm not a fan of this thermostat though. It tends to be too sensitive to the touch sometimes and not sensitive enough other times. If the AC unit acts up again, I'll replace the Thermostat first and see if that fixes the problem. If not, then a trip to the dealer for further troubleshooting.


    If this does happen again try to note whether there are any error codes displayed, as detailed on Page 11 of your thermo owner's manual. Perhaps the thermo is doing exactly what it should be doing to protect the A/C itself.

    Thanks! I'll try to check for error codes. I'm not sure what time this happened. Like I said, I woke at 1am because it got too warm and realized it was off. It had to be off for a little while before I woke up to raise the temp in the camper that much during the night. Thanks again!
  • SoundGuy's avatar
    SoundGuy
    Explorer
    Jul 09, 2018
    RobWNY wrote:
    I think I'll just leave it alone for now but make sure I have the fan on High or Auto if the weather is very hot and humid. I'm not a fan of this thermostat though. It tends to be too sensitive to the touch sometimes and not sensitive enough other times. If the AC unit acts up again, I'll replace the Thermostat first and see if that fixes the problem. If not, then a trip to the dealer for further troubleshooting.


    If this does happen again try to note whether there are any error codes displayed, as detailed on Page 11 of your thermo owner's manual. Perhaps the thermo is doing exactly what it should be doing to protect the A/C itself.
  • RobWNY's avatar
    RobWNY
    Explorer
    Jul 09, 2018
    SoundGuy wrote:
    RobWNY wrote:
    The fan works fine. I had the unit on for hours the next day and had no issues. It just went out in the night when it was very warm and humid and I had the fan on the low setting. The Ac is a Dometic Brisk II Air 13,500 BTU Rooftop Air Conditioner. The Thermostat is the Dometic CT Single Zone Thermostat.


    I have the same unit but mine is direct blow with the thermo as part of the ceiling unit so as I indicated previously I'd suspect the issue is with your wall thermostat as the A/C will only do what it's directed to do by the thermo. According to your Owner's Manual this thermostat does have a Freeze Sensor (as indicated by error code E5) so perhaps it just did what it's supposed to do - shut down the unit until it defrosts, which in turn would explain why it worked just fine the next day.

    I think I'll just leave it alone for now but make sure I have the fan on High or Auto if the weather is very hot and humid. I'm not a fan of this thermostat though. It tends to be too sensitive to the touch sometimes and not sensitive enough other times. If the AC unit acts up again, I'll replace the Thermostat first and see if that fixes the problem. If not, then a trip to the dealer for further troubleshooting.
  • SoundGuy's avatar
    SoundGuy
    Explorer
    Jul 09, 2018
    RobWNY wrote:
    The fan works fine. I had the unit on for hours the next day and had no issues. It just went out in the night when it was very warm and humid and I had the fan on the low setting. The Ac is a Dometic Brisk II Air 13,500 BTU Rooftop Air Conditioner. The Thermostat is the Dometic CT Single Zone Thermostat.


    I have the same unit but mine is direct blow with the thermo as part of the ceiling unit so as I indicated previously I'd suspect the issue is with your wall thermostat as the A/C will only do what it's directed to do by the thermo. According to your Owner's Manual this thermostat does have a Freeze Sensor (as indicated by error code E5) so perhaps it just did what it's supposed to do - shut down the unit until it defrosts, which in turn would explain why it worked just fine the next day.
  • RobWNY's avatar
    RobWNY
    Explorer
    Jul 09, 2018
    The fan works fine. I had the unit on for hours the next day and had no issues. It just went out in the night when it was very warm and humid and I had the fan on the low setting. The Ac is a Dometic Brisk II Air 13,500 BTU Rooftop Air Conditioner. The Thermostat is the Dometic CT Single Zone Thermostat. They look like this and it is a ducted unit
  • Rgtopda's avatar
    Rgtopda
    Explorer
    Jul 09, 2018
    Sounds like to me the fan capacitor is out. Mine would turn on for about 20 seconds then shut off. I went up on the roof had someone turn on unit. heard the compressor kick on but no fan turning. it was a easy diagnose.
  • SoundGuy's avatar
    SoundGuy
    Explorer
    Jul 09, 2018
    RobWNY wrote:
    Or do I have a problem that I thought was frozen coils but is something else?


    You have a different issue as the A/C freezing up won't stop the fan from running ... sounds more like a power issue. You haven't mentioned just which model you have but if it's ducted and is controlled by an externally mounted thermostat perhaps the issue is with it.

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