Thermostat Issues With Dometic Air Conditioner

Crop Duster · 08-03-2016, 03:40 PM

I have a 2016 27HFS Hyper Lite that has a Dometic single zone LCD thermostat. The thermostat seems to work intermittently with the temperature set point. When I go to bed at night I'll set the temp to 60 degrees. Sometimes I'll wake up in the middle of the night because I'm hot and I'll find the A/C is not on. The temp is still set to 60 in the thermostat but it is not kicking the A/C on. If I turn the thermostat off and turn it back on the A/C will come on. This does not happen every night but it has happened a few times now. Any ideas? I looked in the manual but this was not covered in troubleshooting. Thanks

**Bama Rambler** · 08-04-2016, 08:53 AM

Have you tried to initialize the thermostat? If not, I'd suggest you try that. It's worked for a few people.

If that doesn't work you will most likely have to have it or the control box replaced.

Crop Duster · 08-04-2016, 09:17 AM

I have not done anything with the thermostat. I'll do some searching and see if I can find what initializing the thermostat entails.

Update: I found the initialization process in the manual. I'll give that a try and turn it on and see what that does. This morning it was set to 61 degrees and when I woke up it was 71 inside.

**Bama Rambler** · 08-04-2016, 09:39 AM

Please let us know if the re-initialization works for you.

dahagen · 08-04-2016, 12:29 PM

60 is really low for AC. Perhaps the AC is freezing up or the outside temperature is below the point at which many AC's shut off.

veraken · 08-04-2016, 05:44 PM

I recently had a Dometic LCD thermostat installed in my motorhome. I had a similar problem where the unit kept losing communication with the AC units and shutting down. The cause was hot air in the wall cavity meeting the cold air inside. The result was moisture forming on the thermostat PC board. I put Window and Door spray insulation in the wall cavity and a thin piece of foam between the back of the thermostat and the wall. Problem solved. Don't know if yours is the same, but it is something the check.

pdqparalegal1 · 08-06-2016, 12:16 PM

Quote:

Originally Posted by Crop Duster

I have a 2016 27HFS Hyper Lite that has a Dometic single zone LCD thermostat. The thermostat seems to work intermittently with the temperature set point. When I go to bed at night I'll set the temp to 60 degrees. Sometimes I'll wake up in the middle of the night because I'm hot and I'll find the A/C is not on. The temp is still set to 60 in the thermostat but it is not kicking the A/C on. If I turn the thermostat off and turn it back on the A/C will come on. This does not happen every night but it has happened a few times now. Any ideas? I looked in the manual but this was not covered in troubleshooting. Thanks

Are you part Polar Bear? 60 is way low for most people. What was outside temp? The most you can hope for is 20 deg difference.

Take more clothes off and add a floor fan.

Crop Duster · 08-06-2016, 10:31 PM

I had the chance to test it out during the day and it stayed cycling throughout the day. I'm going to be away from home for the next couple weeks but after I get back I'll be sleeping in it again (summer home) and I'll really get to try it out.

I'm in northern MN where it's hot and humid. Outside temps at night are anywhere from 55-65 but it can be humid.

Crop Duster · 08-24-2016, 06:58 PM

I've spent the last 2 nights in the camper after being away for the last few weeks. Last night the A/C did not work correctly again. I had it set at 61 and when I woke up it felt warm inside. I turned the thermostat off and checked the temp on it. The thermostat was reading 69 degrees. When I turned it back on the A/C immediately kicked on.

pdqparalegal1 · 08-24-2016, 07:14 PM

Quote:

Originally Posted by Crop Duster

I've spent the last 2 nights in the camper after being away for the last few weeks. Last night the A/C did not work correctly again. I had it set at 61 and when I woke up it felt warm inside. I turned the thermostat off and checked the temp on it. The thermostat was reading 69 degrees. When I turned it back on the A/C immediately kicked on.

Must be early onset menopause.

geo m · 08-24-2016, 08:36 PM

I am having the same problem with my ac.Posted this here two days ago.I have a control unit on order since I have already replaced the thermostat.I will also insulate behind the thermostat. Dometic customer service said it had to be the thermostat or the control unit.Cost @$85.00:not worth the hassle of taking tt to dealer for warranty,and being without tt for a month.

Crop Duster · 08-24-2016, 08:53 PM

Quote:

Originally Posted by geo m

I am having the same problem with my ac.Posted this here two days ago.I have a control unit on order since I have already replaced the thermostat.I will also insulate behind the thermostat. Dometic customer service said it had to be the thermostat or the control unit.Cost @$85.00:not worth the hassle of taking tt to dealer for warranty,and being without tt for a month.

Thank you for the input. Maybe I'll replace that also. It would cost more in fuel for me to get it to the dealer.

**Bama Rambler** · 08-25-2016, 01:30 PM

There seems to be a rash of units with control board problems lately. I've read a few threads from people having the same issues.

WTA · 08-25-2016, 02:36 PM

No longer a V-lite owner but still follow the site. Have a Keystone Alpine with two Dometic AC's. This past winter in Florida bedroom AC started acting up. Thermostat read 46 when actual temp for the bedroom zone was around 75. Could get compressor to start but would immediately shut down. Went topside and opened AC. The box holding the control board was full of stink bugs. They were walking around on the soldered side of the board and apparently grounding out some of the circuits with their backs against the metal box holding the board. After I cleaned all the stink bugs out AC operation returned to normal.

AGFazio · 08-27-2016, 04:10 PM

Look here.

http://www.forestriverforums.com/for...?do=file&id=94

geo m · 09-04-2016, 01:44 PM

I have now replaced the thermostat and the control board on my Dometic 13500 btu ac. The ac still not coming back on after it reaches set temp. Thermostat set temp at 72,actual temp 79 or above. What else can I check? Does the freeze wire in the evaporator have anything to do with this? Could it be a capacitor problem? I am at a loss at where to go from here.

**Bama Rambler** · 09-05-2016, 12:44 PM

The only way the freeze coil would have anything to do with it would be if the evaporator was froze up and didn't thaw out by the time the unit called for cooling again.

How do you get it to restart?

geo m · 09-05-2016, 01:06 PM

I turn the thermostat off for about 15 seconds,then back to cool mode.Ac starts right up and begins to cool again.I might have to manually turn the unit on two or three times as the temp rises,after that the ac will cycle on and off as it should.This condition happens usually at night after ac demand temp satisfied for the first time. I am running the ac today with ac cycling as it should. I took the ac cover off this mourning,checked condenser,capacitor,and wiring: everything clean and in place.

**Bama Rambler** · 09-06-2016, 11:20 AM

Have you ever noticed any error messages on the thermostat?

It sounds like an intermittent problem with communications.
Since you've replaced the thermostat and the control board, I suspect the wiring. Maybe a bad crimp in the RJ-11 plugs. Take a good look inside the plugs themselves and see if the wires going into the blades look right.

It may be worth your time to ring out the wires and even reterminate them.

Crop Duster · 09-06-2016, 08:48 PM

I have not had time to change any parts out of mine but my problem is also intermittent. Somedays I wake up and the a/c is on and other days I wake up and it's not on and the temp is 10 degrees over what it is set to.

You may also like: