How does the Dometic Refrigerator Work

The Dometic Refrigerators used in the TM have no moving parts, no compressor, etc. The process uses heat to change a mixture of liquid ammonia and hydrogen gas into ammonia and hydrogen gas. The selection of 12 VDC, AC, or propane denotes the source to heat the boiler.

The components of the Dometic are as follows: boiler, pump, seperator, condensor, evaporator, gas temperature exchanger, absorber, absorber vessel, liquid temperator exchanger.

1. The system is charged with hydrogen gas. The boiler, using ammonia, hydrogen, liquid solution condenses ammonia liquid to a gas.
2. The gas, containing vapor, rises from the boiler to the separator, where the vapor is removed.
3. The gas then passes through the condensor and cools into a liquid.
4. The liquid flows through the hydrogen filled evaporator.
5. The evaporation of the ammonia extracts heat from the refrigerator compartment to provide cooling.
6. The solution of ammonia and hydrogen passes on to the absorber.
7. The solution and vapor are returned to the absorber mix with ammonia gas and back to the boiler to repeat the continuous absorbtion cooling cycle.

For an animated display of the above process, go to the following website. http://www.dometicusa.com/products/r...absorption.swf

Ed,

Great post. Another location for trouble shooting, etc. is: http://www.rvmobile.com/welcome.htm.

Jim

Has anyone had to change the 12V heater on the Dometic refrigerator? Our refer works on gas and 110V but not on 12V. I've looked around this site and can't find anything about changing the 12V heater. In fact, the Dometic site is very skimpy with information about the 12V feature.

[Bill]

Jim -

I'm sure you've checked the fuse - one of the little colored ones, not the big black circuit breaker.

Have you confirmed (with a test light or a meter) that 12-volt power is indeed reaching the heating element? It would be a shame to go through the expense and trouble of changing the element, and then discover that it still doesn't work.

Bill

Bill is correct in that it is worth making sure it is not a fuse or simple wiring/connection problem first.
If not, do you have the user manual? I got one with the TM's blue folder and it has instructions for changing out the heaters. If you don't have, you should be able to get one here:
http://www.gasrefrigeration.net/dometic_manuals.htm
The part number for my 12V heater (fridge is the Dometic RM2333) is 173735044
You may be able to get an equivalent online here (it changes the part number to a different one when you enter it - I'd phone to make sure) :
http://www.pplmotorhomes.com/parts/r...ator-parts.htm

Hope this helps,
-Paul

There is no continuity between the wires at the refer when they are not hooked up. There should be continuity with resistance. My DVOM shows an open circuit. I just went out and looked and it doesn't look like it would be that hard to replace the 12V heater. I do have 12 V power, so the fuse is good.