Hi!I have a 2013 Passport with a Dometic rooftop ducted A/C and Dometic single zone LCD thermostat.Yesterday it was working fine.At night, we like to leave the thermostat fan setting on Lo (not Au) so that it runs continuously through the night, for the white noise.Last night, in this configuration, the fan turned off. I can cycle through Au, to Hi, back to Lo and the fan will come on, but still will turn off after a while.Also, separately, I think ... I had the temperature set at 68 but the air temperature is 70. Nothing is running. So I lowered the temperature to 64, still nothing is running.If I cycle through Furnace, Off, Fan -- the fan turns back on.If I cycle on to Cool, the A/C compressor turns on, and the fan does too.What could this be? I'm moving a few hours down the road today -- if this could be a thermostat problem, I could probably find one along the way.Thanks for any help.

I would try rebooting it- turn the system off, press and hold +, press and hold on/off mode for 3 seconds. Screen should read -- , release. Press On/Off to turn off.Should be back at factory settings.

sounds like the unit froze up and you need to do what Chris suggest.Also don't run the unit on low fan

I have the Dometic and single zone LCD t-stat also...I have experience the same thing with my Bedroom AC fan on Low over night, running fan on HI I've had no issues.I don't know if the freeze sensor shuts it off or what, but on high it doesn't experience this issues...Dometic needs to improve this thermostat....it has other issues also, such as the fan switching from hi to lo and back to high as you initially cool the RV in Auto mode...this can also be fixed by using HI until the temp set point is reached.

Beaubeau -My camper is in the shop right now for a very similar problem. The tech has diagnosed the problem as a bad thermostat and it is waiting for a replacement from Dometic.My symptoms are: the AC (comp and fan) will run until the setpoint of the thermostat is satisfied and then cycles off. But it will never cycle back on even though the temp in the camper goes higher. I usually run it in AU mode and the step-down through the LO fan speed happens as it should at +4 degrees. I think if I have it in the LO mode, only the compressor is affected. The only way I can get mine to cycle back on is to turn the thermostat to the OFF setting, wait a few seconds, then turn it back on to any one of the AC settings (LO, HI or AU).Like I said, the repair tech thinks it is a bad thermostat, BUT - I don't know if he is aware of the reset that Chris Bryant described. The tech never mentioned that and I don't think he tried it. So, when you try Chris' suggestion, please post the results here - I may need to get this info back to my tech.Thanx

Hiking Hunter wrote:Beaubeau -Like I said, the repair tech thinks it is a bad thermostat, BUT - I don't know if he is aware of the reset that Chris Bryant described. The tech never mentioned that and I don't think he tried it. So, when you try Chris' suggestion, please post the results here - I may need to get this info back to my tech.ThanxI tried the reset before....no change...I think it is a software issue in the T-stat or AC control board.

Dometic A/C glitch | Good Sam Community

15 Replies

Learjet
Explorer
Jul 29, 2015
Hiking Hunter wrote:
Beaubeau -

Like I said, the repair tech thinks it is a bad thermostat, BUT - I don't know if he is aware of the reset that Chris Bryant described. The tech never mentioned that and I don't think he tried it. So, when you try Chris' suggestion, please post the results here - I may need to get this info back to my tech.

Thanx

I tried the reset before....no change...I think it is a software issue in the T-stat or AC control board.
Hiking_Hunter
Explorer
Jul 29, 2015
Beaubeau -

My camper is in the shop right now for a very similar problem. The tech has diagnosed the problem as a bad thermostat and it is waiting for a replacement from Dometic.

My symptoms are: the AC (comp and fan) will run until the setpoint of the thermostat is satisfied and then cycles off. But it will never cycle back on even though the temp in the camper goes higher. I usually run it in AU mode and the step-down through the LO fan speed happens as it should at +4 degrees. I think if I have it in the LO mode, only the compressor is affected. The only way I can get mine to cycle back on is to turn the thermostat to the OFF setting, wait a few seconds, then turn it back on to any one of the AC settings (LO, HI or AU).

Like I said, the repair tech thinks it is a bad thermostat, BUT - I don't know if he is aware of the reset that Chris Bryant described. The tech never mentioned that and I don't think he tried it. So, when you try Chris' suggestion, please post the results here - I may need to get this info back to my tech.

Thanx
Learjet
Explorer
Jul 29, 2015
I have the Dometic and single zone LCD t-stat also...I have experience the same thing with my Bedroom AC fan on Low over night, running fan on HI I've had no issues.

I don't know if the freeze sensor shuts it off or what, but on high it doesn't experience this issues...Dometic needs to improve this thermostat....it has other issues also, such as the fan switching from hi to lo and back to high as you initially cool the RV in Auto mode...this can also be fixed by using HI until the temp set point is reached.
newman_fulltime
Explorer II
Jul 29, 2015
sounds like the unit froze up and you need to do what Chris suggest.Also don't run the unit on low fan
Chris_Bryant
Explorer II
Jul 29, 2015
I would try rebooting it- turn the system off, press and hold +, press and hold on/off mode for 3 seconds. Screen should read -- , release. Press On/Off to turn off.
Should be back at factory settings.

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Dometic A/C glitch

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