New AC unit by Dometic not working right

[allbrand1999]

Help please I had a new AC made by Dometic 1500 btu heat pump installed and they also changed the circuit board. Well now I have left the area that It was installed. Campers World installed it and it’s not working right and wanted to see if anybody has run across this problem.The AC comes on blows cold for 2 min then stops. The fan and all, regardless how I have the fan set high,low or auto. Then after about 6 min the compressor comes on with no fan runs and then after 2 min the fan comes on for a few minutes then stops again. Then the compressor runs but no fan for about 4-5 min. Then the compressor stops and after 6 min or so the hole thing starts all over again. This happens know matter where I have the thermostat set at 50-80 makes know difference. Oh and I’m hooked up to a 50 amp breaker and I have a volt surge protector on the line I have the proper voltage. This also happens when I was driving with the generator on. Needless to say it won’t keep the motorhome cool.

[CountryB]

When I bought my coach, the previous owner said he had replaced one of the Dometic AC units on the roof, and that he had to replace the circuit boards on the other units to match (he provided me the old cb boards).

Apparently the old Dometic AC units do not work (communicate?) with the electronics in the new Dometic units - or the issue may be with communication with the thermostat units.

Perhaps this is your problem too.

You said the circuit board was replaced too. Was the CB replaced in the old unit (or did you mean it is was replaced in the new unit)?

If it was replaced in the new unit, was it replaced the correct model/pn to work with the old AC unit/?

[BFlinn181]

Did it work properly when first installed and then the problem developed later? I'd suspect that the wiring between A/C and thermostat wasn't done correctly if this issue has been since the beginning.

[allbrand1999]

The cb was replaced only in the new AC. I had a Choice either replace the circuitboard or add a Nother thermostat the board was a little cheaper

[allbrand1999]

The air-conditioner that was replaced was the middle air-conditioner it’s on the same thermostat as the bedroom air conditioner which is an older unit I was told the reason they replaced the board on the new air-conditioner is because the new air-conditioner has a three speed motor and the old one only had high and low

[allbrand1999]

Both of my old units work properly it’s only the new one is giving me this problem

[BFlinn181]

Originally Posted by allbrand1999

Both of my old units work properly it’s only the new one is giving me this problem

You still haven't said if it worked properly when installed and this issue has just developed or it was not working from the beginning. Regardless, you need to have someone look at it to determine the problem. Then you can decide if it was installer error or a warranty issue.

[allbrand1999]

I’m sorry it has done this from the time it was installed. Yesterday I brought it into a dealer and it worked fine. When I left I was going down the road turned on generator and then it started doing the same thing. Now at campground doing same thing. Very frustrating!!!!!

[CountryB]

That happens - you bring it to shop, it works fine. Leave, it acts up.

Could it be that it only acts up on generator (a voltage issue)? Will it operate normally when on Shore power?

[allbrand1999]

No I’m on shore power now and I have a surge protector and voltage checker plugged in before my cord so I know I have the right voltage I know the common is the common and the lines in our the lines and everything is correct as far as the power into the motorhome

[Randyman1]

I would say it is in the settings on the dip switches up on that circuit board that they put on that air conditioner. However, where you said it did work correctly when you took it to the dealer that almost would rule that out. I too, last summer had my middle air conditioner replaced and went the route of buying the circuit board so that it would work with my other A/C on the same thermostat. Check and make sure that the phone type plug got plugged in up in the ceiling, it makes it talk to the thermostat and also that the wires have been securely connected. After having mine replaced I discovered later that my aqua hot on zone two wouldn’t work and they had connected a couple wires wrong. Fortunately I had watched them do the installation and wiring and I knew that there was a couple choices because are so many extra wires up there in the ceiling based on different models I guess. You definitely did right by buying the circuitboard and your unit will work with your old thermostat and your other air-conditioners because of doing that. I think you might have a wiring issue other than you said it did work correctly once which means maybe it is wired correctly and you have something defective in the new unit.

[RamiDav]

I wonder if it could be something as simple as cold air aimed at the thermostat
sensor .
In some cases it can run a person crazy with cycling and premature cutting off.
Find the sensor and look at the air vents near by , turn them some and test
again .

Ray

[allbrand1999]

Good news I called Dometic and told them everything. They had me reboot the thermostat and it works fine now. FYI turn off thermostat push and hold mode & zone at same time you will see (ff) then release you will see 1-2 then reset your zones the way you want.

[CountryB]

Glad you figured it out - and posted back to share.

I assume you only needed to reboot the thermostat for the new AC unit (and the others,like bedroom, are okay).