Frig works on AC Power but not Propane

[DaveWarde]

Our refrigerator works on 120VAC, and is not cooling with Propane, which has worked very reliably in the past. We are heading out for 2 weeks in less than 2 days. If anyone has experienced this problem and has technical suggestions I would love to hear from you.

• ’21 30 Ft Airstream Classic
• Dometic RM3962 Refrigerator 120VAC or Propane (needs 12VDC for propane but this model is not designed for battery operation)

We cooled the frig down on AC Power, setting it on “5”, the coldest setting for about 36 hours. The frig temp after this time was 33F.

We then switched off the AC to make sure it would run on propane. We verified that the propane heater was lighting and running steady. (In addition to the sound of the furnace lighting and burning, I carefully felt the “chimney” and it was hot.)

After several hours we noted that the temp of the the frig had risen to 50F and then several hours more, it had worsened to 60F. The weather was not hot today, maybe a high of 75F.

I have checked all the DC voltages, and checked the three known fuses, including the 3A inline for the ventilation fans at the top of the condenser, and the two 5A fuses in the lower control circuit board. Everything appears fine, voltages and fuses are good. (Though I’m no specialist in HVAC or refrigerators, I do have a fair amount of experience as an electronics technician. I have all the manuals and can read the schematics).

[richard5933]

If it's cooling on electric, then the cooling unit is working. These are purely mechanical cooling units which rely on a heat source in the chimney to get the system going. The electrical bits only serve to get the heat source fired up, whether it's the electric heating element or the propane flame.

So, if your unit works on electric it should be working on propane, especially if you have a flame.

My first thought is to ensure that the flame is burning cleanly and centered in the opening. It's got to heat the correct place inside the chimney for it to work, so perhaps you've got a nest of some type further up the chimney blocking the heat from reaching the cooling unit. The electric element is physically mounted alongside a cooling unit tube, so it will continue working even with a nest or blockage in the chimney, but the propane side relies on the heat from the flame reaching the cooling unit tube through the chimney. Blockage or nest = no cooling action.

There are some great videos out there that walk you through the steps of cleaning the flame area and the chimney. There are cleaning brushes you can get from Amazon designed for cleaning the chimney. My guess is that all this will correct the problem.

[azflycaster]

I had the same issue recently, but the flame was not as big and the noise was not as loud as it had been. The tube that the propane is blown thru from the orifice and has the slots that the flame burns from had some blockage. Most likely a spider had taken up residence. Cleaned out the tube and tempertures went back to normal.