Dometic RM46E Gas Starting Trouble

[bentSpaceTime]

The Dometic RM46E - three way refrigerator in our trailer has been having trouble lately getting started. The last couple trips we took, we pulled it out into the street where it was somewhat level like we always do and tried to start it several times on gas and failed. The flame seemed not to ignite at all. I leveled the trailer in the driveway and opened up the back compartment to do some tests. The piezo lighter seems to be working fine. Now for some reason the flame is lighting, but goes out when you let go of the knob for releasing safety device. Sometimes we can eventually get the flame to stay on, if we kept that knob pulled out for a minute or two.

Any idea what’s causing the problem here?

Found a manual for the fridge online: http://cortezcoach.com/wp-content/uploads/2016/01/RM46e-dometic.pdf

On the last page it says:

48. PERIODIC MAINTENANCE
Once or twice a year depending on use, it is recommended to clean and ad just the burner assembly, Proceed as follows:
1. Disconnect the gas pipe from the burner assembly,
2. Bemove the burner housing.
3. Remove the jet,
4. Clean the jet with alcohol and compressed air ONLY.
5. Clean the burner tube and especially the gauze with a brush. Blow with compressed air,
6. At the same time, check the flue baffle: that it is clean and free from soot. Heavy soot formation indicates improper functioning of the burner. Clean baffle and flue. Further, clean cooling unit and floor under refrigerator.
7. Reassemble.
8. The entire gas installation should be checked for leaks at intervals. Test all pipe connections with soapy water, not with an open flame.
9. Check the burner with full flame (MAX) and with by-pass flame (0).
Note: The thermostat will not close to by-pass on- setting “0” unless the refrigerator has been working for a few hours and the thermostat bulb is cooled down to at least 6°C(40°F).

Hasn’t been cleaned since we’d had it and judging by how rusted on the screw that holds the burner housing on is, I’m not sure if it’s ever been cleaned.

Does anyone actually do this maintenance?

Is it necessary?

Would it help this problem?

[bentSpaceTime]

What do you use to clean the burner, a wire brush, or would a toothbrush work?

[dougrainer]

bentSpaceTime wrote:

dougrainer wrote:

YES. You will be surprised at how dirty the burner area will be with rust and flaking paint and such. IF you have access to a compressor, blow out the flue above the burner, to remove build up on the Spiral baffle INSIDE the flue tube. I rarely remove the burner, I clean out with a small brush and compressed air from the shop compressor. Then vacumm up the debris. Doug

Cool! So, not necessary to remove the burner housing, if I do it that way?

yes.

[bentSpaceTime]

dougrainer wrote:

YES. You will be surprised at how dirty the burner area will be with rust and flaking paint and such. IF you have access to a compressor, blow out the flue above the burner, to remove build up on the Spiral baffle INSIDE the flue tube. I rarely remove the burner, I clean out with a small brush and compressed air from the shop compressor. Then vacumm up the debris. Doug

Cool! So, not necessary to remove the burner housing, if I do it that way?

[dougrainer]

bentSpaceTime wrote:

dougrainer wrote:
Take a 5/16 open end wrench and tighten the nut from the Thermocoupler at the safety valve. Odds are it is slightly loose and that will stop the millivolt signal to the valve. Doug

Wow! Took 2 seconds and it appears to have fixed the problem! Thank you!

Is there any reason to cut off the rust on screw and do the recommend cleaning preceedure from the manual?

YES. You will be surprised at how dirty the burner area will be with rust and flaking paint and such. IF you have access to a compressor, blow out the flue above the burner, to remove build up on the Spiral baffle INSIDE the flue tube. I rarely remove the burner, I clean out with a small brush and compressed air from the shop compressor. Then vacumm up the debris. Doug

[bentSpaceTime]

dougrainer wrote:
Take a 5/16 open end wrench and tighten the nut from the Thermocoupler at the safety valve. Odds are it is slightly loose and that will stop the millivolt signal to the valve. Doug

Wow! Took 2 seconds and it appears to have fixed the problem! Thank you!

Is there any reason to cut off the rust on screw and do the recommend cleaning preceedure from the manual?

[Chris_Bryant]

dougrainer wrote:
Take a 5/16 open end wrench and tighten the nut from the Thermocoupler at the safety valve. Odds are it is slightly loose and that will stop the millivolt signal to the valve. Doug

Do this first.

[dougrainer]

Take a 5/16 open end wrench and tighten the nut from the Thermocoupler at the safety valve. Odds are it is slightly loose and that will stop the millivolt signal to the valve. Doug

[bentSpaceTime]

Any good ideas for how to get that screw out of the burner housing. It’s complety rusted. Sprayed a bunch of Blaster on and tried an impact driver, which just striped screw. Not sure if it’s thick enough to use an easy out...

[Chris_Bryant]

Those thermocouples hardly ever go bad, and they are not standard thermocouples, so you cannot replace one with a hardware store model. They *can* go bad, but after cleaning the burner, unscrew the thermocouple from the safety valve and clean the end with a pencil eraser. This is an electrical connection, and they can get corroded.

[drsteve]

Bad thermocouple, most likely. Replace it, they're cheap.

[MySuncoastRV]

Yes.

[bentSpaceTime]

Thank you. Is the part of the thermocouple that sits in the flame, the only part that is cleanable?

[MySuncoastRV]

If you are getting the initial flame then you know the gas valve is opening as commanded. It sounds like the thermocouple is your issue. Remove the cover and look for deposit buildup. Scrape it clean if anything is visible. You can also bend it very slightly putting it closer to the flame. A failing or dirty thermocouple will give a false reading which will simulate a flameout therefore commanding the gas valve to shut off. Please post your results.