Dual Air Conditioners stop working

[RMcNeal]

We just noticed in the last few days that the dual A/C units we have will stop running and will not come back on until I turn off the thermostat and wait about 30 seconds and turn it back on. This was not the case a week ago. Here's what it seems to be doing...
Set kitchen thermostat for rear a/c to 68 degrees, unit turns on and runs. Set bedroom thermostat to 68 degrees, unit turns on and runs. After a while, both units get down to temp and shut off as expected. The seem to cycle appropriately for a while, then at some point shut off. Temp goes up and up, as high as 75 degrees or more but neither unit turns back on. Finally, I turn the thermostat off, wait about 30 seconds, and turn it back on to cool and auto as before with the same temp setting of 68 degrees. Unit kicks on and runs as it should and the cycle starts all over again.
Am I missing something or should these not be a set it and forget it system? They have seemed to work as expected since we got this 5er in October last year. This definitely is a change in how it works. I was told that these two units work together to cycle back and forth and maintain the temperature. They are both 15K Whisper Quiet units with the Dometic touch sensitive thermostats. Any ideas would be greatly appreciated.

[Jeff n Susan]

I'm no HVAC expert, but I would be looking at the thermostat to be the guilty one.

[GHallof]

I seem to recall having a similar problem a while back. Instead of turning off each thermostat, which one would think would fully reset them, try pulling each stat off its base and then re-seating them. If memory serves...I had to do this a couple of times each before everything worked as expected. Have no idea why...but that did the trick.

[RMcNeal]

Thanks. I'll give that a try today.

[RMcNeal]

OK. Mine are the capacitive touch thermostats. The face place comes off, but the body of the thermostat is wired and screwed to the wall. I pulled off the faceplate and reseated it. Display reads "--". After the light goes off, I pressed mode and it reads "off". Set it back to cool and auto at 68 degrees. It will take some time to tell if that fixed it, but at least they are running and cooling.

[GHallof]

What you described is exactly what I saw when I removed and reseated mine. Hopefully this will do the trick. I saved an interesting link on the topic but for the life of me I can't locate it. Once I do Ill post here

[RMcNeal]

Thanks so much, GHallof. I went through my paperwork and all I can find is a one page user guide on the thermostat. Most basic common sense stuff. No real help. I'm trying to find a manual or some other info online now.

[GHallof]

I also remember something about ensuring that the fan speed is left on AUTO when in cooling mode as you have it set. Again..do a search on the CT stat specifically through google and you'll most likely come across the threads. Happy Trails...Stay Healthy

[RMcNeal]

Thanks. You as well. I did remember reading somewhere about the "auto" vs low or high in relation to the furnace, but it seems to make sense heat or cool for me.

[RMcNeal]

Well, so far it appears to be working normally again. It's been nearly 24 hours and the a/c has continued working as expected. Thanks again for the help!

[GHallof]

Glad to hear it! When it happened to me I was working a job in AZ right at the start of summer. Imagine my frustration trying to stay cool. Safe Travels!

[jsb5717]

Dumb question, but are you connected to 30amp or 50amp service?


Edit: Nevermind...that would trip the breaker and that would be obvious. Didn't think it through

[RMcNeal]

There are no dumb questions. Yes I'm on 50 amp and progressive EMS says all is good. It just seems to be something with the thermostats and multi zone a/c best i can tell.

[triplebvalp]

You can reset the t-stats by pressing the + or up button and the mode button at the same time. Hold both in until you get - - on the screen. Let go of both buttons and the press the mode button twice. That will put the t-stat back to factory default.

[allenclme]

Originally Posted by RMcNeal

There are no dumb questions. Yes I'm on 50 amp and progressive EMS says all is good. It just seems to be something with the thermostats and multi zone a/c best i can tell.

Mine would just shut the system down. There was an issue with the faceplates. I called Dometic customer service and they shipped me two new ones. Don't know if that is what you are experiencing, but that solved my problem.

[fulltilt]

Hi Have you checked your return air filters, with a 68 degree setpoint, & low air flow, setpoint won't be achieved & frosting of the evaporator will result to the point that little air will get through, air volume is the key. Usually a thermostat reset is required to reset a safety lock out, in this case a freeze stat.

[qckurt]

Same thing happened to my unit the first 2 years I owned it. Brought it back 3 times to dealer before they put in 2 new thermostats. Turned out they never checked or were able to duplicate it because they did not have a 50 amp plug in their service bays. Unbelievable!!

[Frank64]

I had the same issue when I bought my Monty 3791 RD
The ac upstairs would not come on
I had to press and hold the Mode button while pressing the up button approximately 3 seconds I got a — symbol
I was able to set thermostat to auto and air at desired temp
I had to do this on two separate occasions
since last summer I have not had any issues

[lj_cox]

This has been happening to us, only with the rear AC unit. I cleaned the air intake filters and it improved a lot. Still happens from time to time when the air is very humid; I think it's a freezing issue related to airflow and moisture.

[Frank64]

You might be right
Have you taken your rig to a service tech and have them look at it ?