Problem with Newport Air Conditioners

[mthompson]

We have a 2020 Newport. I wrote before about the thermostat being on the outside wall...putting that issue aside, here's my new question. We have 3 a/c's with 3 separate thermostats. They are the basic Dometic thermostats. The air conditioners work perfectly as far as cooling goes, but the set temperature and cycling is all wrong. If I set all three thermostats to 70, the a/c's will run and cool down perfectly. But, when they reach temperature, 2 of the 3 will cycle off and never come back on. I have to turn them off, count to 10 and turn them back on. Then they will do the same thing again. Meanwhile, the third a/c is on running continuously. Yesterday, the living room and bedroom a/c cut off while the center a/c continued to run. Today, the center and bedroom cut off while the living room stayed on. We are second owners and the first owners had trouble (unknown what the trouble was) and Heartland changed out the thermostats. So, all three thermostats are relatively new. Last week, I called Dometic and they told me to change out the thermostats. I don't think that is the problem.

Does anyone out there have any suggestions or ideas what might be going on here?

 

[david-steph2018]

Look at the communication cable for the ACs. It is the phone cable, make sure the connections are seating good and not corroded. If nothing is wrong here, at least you can rule out the cable/connections there.

 

[mthompson]

Look at the communication cable for the ACs. It is the phone cable, make sure the connections are seating good and not corroded. If nothing is wrong here, at least you can rule out the cable/connections there.

Where is this communication cable?

 

[david-steph2018]

It looks like the old-style phone cable that was in your house. It goes from the back of the thermostat to the AC unit. It is how they talk to each other.

 

[mthompson]

It looks like the old-style phone cable that was in your house. It goes from the back of the thermostat to the AC unit. It is how they talk to each other.

Ok. Thanks. We'll give that a try this afternoon.

 

[jmarnell]

We had a problem with one of our AC's cycling off and not coming back on until I cycled the thermostat off and on again. A mobile RV tech finally diagnosed the problem as a bad relay in the AC control box. He replaced the control box and we haven't had any problems since. It does seem strange that all 3 units would be having this problem, but thought I'd pass on what worked for us. The control box in our unit is a small gray box that is inside the ceiling, accessed by removing the ceiling cover of the AC.

 

[mthompson]

I found this possible explanation in a forum.

Yep, I've had the same problem - same symptoms. My experience was shared in post #22 in this thread. The problem is caused by air leaks between the input chamber and output side. This is the same thing Cavscout found in his AC. His fix is repeated here:

I also taped the white foam back to provide a complete seal, but in my case the actual metal air dam was pulled away. Either way, you just have to stop air that should be going out to the ducts from circulating back to the return side, "short circuiting" the normal path

 

[david-steph2018]

Start with the easy things first and eliminate this area the cause. But just thinking here, this is a 2020 you may still be under the manufacturer warranty. Not Heartland but the manufacturer of the AC unit. Sometimes these have a longer warranty period, I think 2 years. Maybe contact them and ask, if they will pay for a mobile tech if you cannot figure it out.