Dometic fridge works only on LP for a couple of months

sounds like you tested everything except the ac/gas switch on the fridge?

hydrocynus wrote:
BTW. My manual states 3 year exclusive warranty.

I know, but the manual is wrong. They never reprinted the new warranty terms. Still YOU modify a under warranty product with aftermarket parts and you VOID the warranty. If you brought that unit to my shop and I see the Dino board, you would then be PAYING me to fix it as Dometic will also NOT pay to fix. Why did you not just take it to a Dometic Service Center? Doug

BTW. My manual states 3 year exclusive warranty.

Sorry about the discrepancy. The title says 2 months but my post states 2 year. The correct time is 2 months.

The unit is correctly set to auto. It used to cool on ac when set on auto. To test the unit i disconnected the temperature sensor. It then cools on LP but not AC.

hydrocynus wrote:
Old Biscuit. With a refurbished board, I still get the problem. So, it is not the board (unless the refurbished board is bad). This is why I am perplex. I have returned the circuit board and ordered a brand new one. Amazon refunded me my money and with amazon prime, I do not pay shipping.

Once you replaced the Dometic board you have NO warranty from Dometic. Besides, the Dometic warranty is 1 year. You state you have had the problem for 2 or more years. Are you positive you are setting the Auto button in the correct position? Are you aware that unless the refer calls for cooling the unit will not switch to 120? Doug

Old Biscuit. With a refurbished board, I still get the problem. So, it is not the board (unless the refurbished board is bad). This is why I am perplex. I have returned the circuit board and ordered a brand new one. Amazon refunded me my money and with amazon prime, I do not pay shipping.

Hello all, thanks for the speedy answers.

I checked the AC input and it is correct. I also used my oscilloscope to see if it was good. Further, I switched the AC supply to the another one and the fridge still does not switch to AC cooling.

On the board level, I checked that the board is indeed receiving AC supply. All good there.

The Board is also receiving the right amount of voltage. I checked it for all the circuits that carry 12V.

All the fuses have been checked and they all show a close circuit.

The AC heating element reads 44 ohms when unplugged from the the board.

The only thing I have not checked is to directly plug the heating element to AC and see if it warms up. Since the heating element tested 44 ohms, I considered it good.

I am not specialist in Dometic fridges but I do repair and test my circuit boards of my scientific equipment. So, I am not totally ignorant about circuit boards.

Cost of the board was $35 bucks, heating element is another $35 bucks. To me, it does not seem that it is very expensive compared to having the dometic guy come over. Plus Amazon gets all the parts back with no questions asked.

On a Dometic a BAD heating element will not stop the switch to 120 electric. The only symptom is, NO cooling since the 120 element is bad. AS you found out, doing your own diag just cost you money. Don't knock a specialist, since you don't know what you are doing. IF the problem as Old Biscuit mentioned is probably inadequate voltage or a bad 120 supply to the refer then that would NOT be a warranty concern either. You need to verify the 120 at the supply receptacle and at the 2 inputs on the new Circuit board from the 120 pigtail. Doug

Is there AC power at the outlet the fridge is plugged into? For that matter, is it plugged in? It sure sounds like it's just not seeing AC power for some reason, which should be relatively easy to track down with a multimeter, though of course one needs to be careful when doing so.

1st off....
Have you checked.verified that the 120V AC Outlet fridge plugs into is HOT?

If Hot then need to check that circuit board is getting AC Voltage

J5 is Line (Hot--Black wire)
J6 is Neutral (White wire)

Then verify that the 5A glass fuse (120V AC) is functioning (test it....not just visual) and fuse clips also

J7 & J8 are heater leads (black wires)
GREEN wire & Green/Yellow stripe is 120V AC ground

Got AC Voltage but still swaps to LP.....that would be a circuit board issue not heat element

You can test heat element by removing leads from circuit board and plugging them directly into a working outlet
(tests/verifies element works or not and bypasses circuit board)
After a few minutes you can tell whether or not element gets hot