Dometic Royale Refrigerator doesn't work on LP gas.

[furnguy]

Sent: 6/14/2007

In my 78 Chieftain I have a Dometic Royale two door refrigerator with the freezer on top.
It worked fine until this February when on a trip and now it only works properly on AC. When switched over to "gas" it may run for one minute or for 5 hours, but will eventually go to "check" on display. I took the gas valve out and the thermo couple and cleaned everything with a brush and compressed air, but still it lights and stays lit for a while but then goes out. The igniter works well and them gets red hot from the flame.
Any ideas what could be the problem with it only wanting to run on 12v or 110?
Thanks for any help or ideas.
Keith

[denisondc]

Sent: 6/15/2007

Your fridge is a later model -- mine is old enough that the 'igniter' is a Bic. Have you tried poking around at www.dometic.com? On their 'service' page they allegedly have an email address for requesting Service Manuals for fridges that aren't in production anymore.
Another thing to check is that your propane pressure is correct. I had a bad pressure regulator and just replaced it, but here is a URL that describes how: www.rverscorner.com/manometer.html.

[furnguy]

Sent: 6/17/2007

Thanks for the info- will check them out and report.
Keith

[ClydesdaleKevin]

Sent: 6/17/2007

If all else checks out OK, remember that our fridges (mine is similar in our 77, but its a Norcold) have old school circuit boards in them, called Dinosaur Boards.  Sometimes they go bad and can result in many symptoms, including the ones you have.

If all else checks out OK, you have a couple of options...the cheapest is to remove the fridge and take the whole thing to an RV dealer...I did that in my own rig, and the dealer I went to troubleshot it for free...the second cheapest option is to drive the rig to the RV dealer and let them check the fridge in place...it might cost a bit, but if its a dino board, it won't cost TOO much to fix.

Good luck!

Kev

[DaveVA78Chieftain]

The name Dinosaur is a brand name of replacement control boards.

From the RVmobile website:

Trouble shooting Dometic Gas System (second generation)

Troubleshooting Gas problems generally fall into three categories. One, the flame doesn't light. Two, the flame lights but goes out and the check light comes on. Three, the flame lights and stays lit, but the refrigerator doesn't cool.

(1) If the refrigerator doesn't light when it should, the first thing to do is verify that the refrigerator works on AC (electric). This lets you know that other critical parts are doing their job. Turn the temperature control all the way up to insure that cooling is called for. Assuming everything else is alright, select gas at the eyebrow and check to see if the solenoid and igniter are attempting to work. Usually you can hear the gas solenoid open, or you can put your finger on it and feel it when it opens. If the igniter is working, there will be sparking at the burner. If one or both of these components fail to work, check for 12 volt to them. If there is no power to one of them, the main circuit board is bad. If 12 volt is present at the component that isn't working, then there is a problem with that component. For an apparent problem with the igniter, see the igniter page. With a solenoid problem, test for 12 volt across its two terminals. If 12 volt is present and the valve doesn't open, the solenoid valve is bad. By checking across the terminals you are insuring that a ground is present. If everything seems to be working as it should but the flame doesn't light, be sure the propane is not shut off (including at the refrigerator itself). Also, though very rare, there is a possibility that the orifice could be plugged.

(2) In a situation where the flame lights but goes out, the problem is going to lie in the thermocouple circuit. This would include the thermocouple, the flame, and the circuit board. If the flame is a clean burning flame, it is probably OK. When heated by the flame, the thermocouple should produce between 25 and 35 millivolts. This can be measured at the wire connectors at the end of the thermocouple wires. If you're getting the millivolt readings mentioned and still have the check light problem, the cause is the circuit board. In fact, the circuit boards on these models are somewhat notorious for having a problem with the thermocouple circuit, resulting in an erratic check light problem. We have been replacing these boards with an after market board, the Dinosaur brand P-711 with very good success. It has a 3 year warranty and a special thermocouple circuit.

A side note: sometimes when traveling the flame goes out, doesn't re-light, and the check light comes on. This can be caused by the flame drifting away from the thermocouple when the vehicle is in motion. There is no adjustment for the thermocouple, but the metal bracket holding it can be bent so the thermocouple is further into the flame.

(3) If the gas flame lights but the refrigerator doesn't cool properly, your problem would be in the flame itself or the cooling unit. Try the refrigerator on AC (120 volt) to eliminate the cooling unit as a possibility. If it works on AC, the cooling unit is not the problem. That leaves the flame. A problem with the flame is a basic problem that can affect even the oldest model refrigerator. See the burner page for tips on fixing a bad flame.

[furnguy]

I ended up ordering a new replacement electronic module (board) and all is well.