Dometic Duct and Non Duct A/C roof air swap

On most you won’t need parts (as long as the electronics are in. Separate box), but it is very, very unusual to have that many bad units in a row. That really points to bad installation, which I would bet is due to defects in the ductwork.

Indeed unusual, The first living area unit that came with the rv was pure junked, 2016 trailer and the unit was a dud from the get go.
The second unit worked for about 2 months, then exibited the same problem as the previous unit. The 3rd seems better but not if its hot outdoors,
The rv tech said dometic had a whole batch of bum units , was a compressor pressure and amp draw problem if I recall correctly .

So the Unit is the same, diff being ceiling hardware and mount option.

Ductwork what I thought, But I did mod it to shoot straight out in the living area, And just cools poorly . Strait from exhaust.

Bedroom AC units will ALWAYS be colder output than living room area units. The reason is, EVEN with a common duct. The bedroom turns over a smaller volume of air. Which yields colder temps. Now, you state 1 is duct and the other has a ceiling kit. Explain that. Usually the bedroom is the ceiling kit AC and the Kitchen/LR is the top mounted AC. Did they combine the ceiling kit AC to the Ductwork? Swapping the units will not yield better cooling. 13.5 is 13.5. They either WORK or they do NOT. No partial cooling. So, as Chris stated, odds are you have a installation error on the one not cooling correctly. Which points to the RV dealer Techs as incompetent, as they should have the knowledge to test the Roof units before they replace. Untrained/incompetant people replace parts when they have no knowledge of what they are doing. I would try another Service Center. Doug

Correct, The tech did test the living area unit before replacing , each time,
The first 2 apparently had compressor amp draw issues. ?

hbarker wrote:
Correct, The tech did test the living area unit before replacing , each time,
The first 2 apparently had compressor amp draw issues. ?

VERY unlikely. Yes, Dometic had some bad units, but over 3 years ago and those are long gone. Find another Service Center. If bad when replaced they would have been bad from day 1 not down the road. Doug

To determine if an A/C unit is operating to capacity one needs know the temperature of the air entering and leaving the unit. You say the output of one unit is 58 degrees. If that is the case and the temperature of the return air is 75 degrees or above, the A/C is doing all it can and the only solution is a higher capacity unit.

prichardson wrote:
To determine if an A/C unit is operating to capacity one needs know the temperature of the air entering and leaving the unit. You say the output of one unit is 58 degrees. If that is the case and the temperature of the return air is 75 degrees or above, the A/C is doing all it can and the only solution is a higher capacity unit.

Yeah, Turn on both units on a hot day and LR air output is 58 to 60 deg. BR output is 48 deg. this is shortly after compressor kicks in .
LR unit NEVER blows any cooler., This is Strait Out Of unit. Not the ducts.