Dometic Fridge Not Cooling on Propane

If it is working on shore power, then it is likely that the problem is in the burner/flue area and possibly the gas line.

Thanks StephenH, again excellent insight, I have a 2019 179 and have been using the fridge on 110v, 12v and gas with no problems until this pass week when we were boondocking in Northern Michigan and the gas mode just stopped working no forewarning and the week was very overcast so we could not use 12 volt and solar.  When I got home started digging into the malfunction after reading your write up (thank you) and I started with a good blue flame on the burner when using gas, found that on the 110v mode the fridge worked well.  Checking further found out the flue stack temperature on the gas exhaust vent at the bottom was in the area of 240 degrees and at the top of the flue stack about 230.degrees  I had no base line to compare it to.  So I disassembled the gas burner after disconnecting all power 12v, 110v and the gas.  I couldn't remove the gas burner from the fridge area because of the hard wiring to the igniter and the flame sensor.  So working in the confined space I disconnected the gas feed at the gas on/off valve that runs to the burner orifice while leaving that line connected to the burner assembly (the pipe is about 10" long).  I was able to rotate the burner (separate part from the orifice) and used compressed air to clean out the burner head, the gas line to the orifice and the flue stack.  Also I ran a shot gun cleaning brush up and down the flue stack several times.  I did not see any obstacles in any of the parts prior to the cleaning process like a mud dobber nest or spider cobwebs.  I couldn't evaluate the gas orifice prior to cleaning with compressed air.  After reassembling all the parts and checking the gas connection at the gas valve with soapy water and turning the everything back on (gas and electrical) and leaving the fridge run for about 2 hours the inside fridge temperature has dropped 10 degrees, the bottom temperature on the flue stack is about 550 degrees, the top temperature on the flue stack is about 350 degrees and the refringent line by the top of the flue stack has risen from about 230 degrees to about 330.  Another noticeable outcome is that the flame is now louder and I can easily hear it burning.

Thank you StephenH. The fridge is working now. Really appreciate the help.

Also a drop in the stack temperatures may mean that preventive maintenance is called for, like cleaning out the gas orifice with compressed air before the fridge just stops cooling.  That's my plan at least.