The following is for my Dometic (early models may be branded Electrolux) C40/110 RM4401 3 way motorhome fridge fitted in our van in 1998 but will be relevant to many other earlier and later fridges.
Important: If you are not confident working with electrics and gas piping/burners then please seek the help of a gas registered professional or proper Dometic engineer.
Due to other commitments this week is the first time we have used our motorhome this year. Upon arriving at our first destination we found the fridge was not getting very cold when running on gas. There can be several reasons for this and the most common is listed below:
- no gas or gas pressure is low (maybe a close to empty gas tank or faulty regulator)
- burner jet is blocked
- burner nozzle is blocked
- gas pipe is blocked
- gas flue is blocked or sooted up
- loss of coolant gas – get the coolant recharged/topped up
- magnetic seal on the door is broken or dirty – clean the seal and/or adjust the door hinge for best seal
- insufficient coolant gas circulation due to fridge/van not being level – ensure van is level
Most of the above can be easily checked and rectified by a good DIY’er.
If the burner nozzle is blocked it can be blocked by soot dropping down the flue and laying in the nozzle thus blocking the nozzle. Blowing the dust out can be a quick and easy fix.
If the gas jet is blocked, this is a bit more difficult to clean out. The jet is a small delicate aluminum foil looking “nipple” with a small 0.4mm hole in. These can get easily blocked. To get to the jet you can try to blow compressed air in to the tiny hole or dismantle the whole burner. Here’s how…
In my case I had to remove the bottom fridge vents as well as the plastic surround.
Once the metal screening around the burner is revealed this also needs to be removed. The white plastic bucket is the condensation tray. You may need to remove the tray to get to the screws.
In the photo above you can see the burner with nozzle at the bottom of the cylinder on the right and the jet is just visible through the small hole in the centre left of the long aluminum bar. The stiff wire going to the burner is the themocouple which operates the igniter spark and must be in the path of the flame (it must be kept hot otherwise the igniter will continually spark). The flexible wire is the piezo-electric igniter sparker. If you have to remove these carefully note their position.
A small screw holds the burner on to the bottom of the flue. Carefully remove the screw and pull the burner down and out of the flue. Be careful not to stress the gas pipe or the cables.
Once the burner is removed you can see a daisy shaped nozzle down the cylinder. Blow any dust, soot or rust from the nozzle.
If you need to replace the jet then the burner needs to be removed from the gas pipe. Carefully unscrew the gas pipe from the burner. In my case I found rust had formed around the end of the pipe and was blocking the gas jet. A pipe cleaner pushed down the pipe cleaned this out (I first had to do this 1.5 years ago and after this time it has blocked again).
The jet can now been seen inside the burner. This is a small 8mm foil nipple with tiny hole in the end. Its very delicate so handle it with care. If replacing then ensure you get the right jet for your fridge and burner.
Once cleaned or replaced then carefully re-assemble. Before placing the burner back on the flue you may wish to clean the flue. This can be done from either top or bottom but as the bottom is already exposed it can be done from here. I found a long piece of flexible metal wire, fixed a piece of cloth to the end and inserted it in to the hole. Pushing it up and down the length of the flue just as you would a chimney. Then tap the flue casing to dislodge any lose bits.
Now re-assemble and test. In my case I tested it before I replaced the metal screening so I could see how large the flame was. Prior to cleaning the flame was about 5mm above the burner and hardly visible. After cleaning the flame was now much larger rising about 3 or 4cm and had a definite roaring sound. Upon testing the fridge temperature was down to 5c within 2 hours, instead of 14c after about 6 hours.
Incidentally I have also read that completely removing the fridge and turning it upside down for 24 hours and then refitting can recirculate the coolant gas but I’ve never tried it.