First Post, Out of Frustration over Dometic AC

[Jsledder]

First off, glad to have found this site as it appears to have lots of good information from fellow RV'ers. We are currently living in our Forest River Wildcat 5th wheel for going on a year now (new home being built). Ever since buying this camper new in '16 we've had issues with the AC, the thing seems to start/stop alot while it's cooling, I realize it should "shift" the fan to Hi if it's too far out of range on the thermostat but it doesn't seem to do that very often, it will shut the fan off (not compressor) several times in the course of a few minutes or it will just run flawless all day, never know. Well, earlier this year the thing wouldn't come on at all and I just figure it bit the bullet, so I bought a new one and installed it, guess what... same thing but at least it ran. A few weeks go by and it refuses to start again, T-stat is set as 72 and it's almost 90 in here, I call the dealership and they tell me that more thank likely either my T-stat or control box is bad so I drive 2 hours to get a new control box and T-stat, install it and and same thing. So now I'm thinking I have a good AC unit thrown into the dump pit and something else is the problem since I just spent $1600 on a new AC/Control box/T-stat. What else is there besides wire running from the AC to the T-stat.??
Right now we are having to basically reset the thermostat each time it shuts down, it will run and satisfy the thermostat and when it shuts down it will not restart without doing that, which really sucks at night!!! During the day while it's so hot it just runs all day.
I'm at a loss!! I'll try and search the forum for more tips.

[dougrainer]

1. Need Model of AC
2. need P/n of Control board
3. need model of tstat. Is the tstat a single zone LCD square tstat? 3 wires going to wall tstat?
4. Is the Freeze thermister installed in the evaporator?
5. Ducted AC system?
6. Separation plenum installed between the air intake(filter) and cold exhaust plenum?
7. TOP mount AC unit or you have the 4 bolts from inside the RV? Doug

[DancinCampers]

I am not familiar with Dometic units, I have 2 Coleman units on my coach, controlled by a single tstat. If your tstat controls the unit thru a data wire vs the normal 12v Y1 wire, then interference could be the cause. I had pursued my issues for almost two months before I tracked the culprit to an ac to dc 12v wall transformer. Once I replaced the transformer units have been trouble free. I would start by turning off all your 120v breakers except for the main and the a/c unit. See if the unit will run normally. If it does, then I would begin turning on the other breakers one at a time, monitoring the unit. My issue was found when I turned on one of the general receptacle breakers on the inverter sub panel, which happened to control all my entertainment systems in the coach. The transformer powered my HDMI to CAT5 conversion module and was hard to locate. This may or may not be a solution for your system, but I would find the schematics for your tstat to see if it controls the unit thru a data wire.