Norcold Refrigerator Carbon Buildup on Flame Probe

[KenS999]

Hello I have a Norcold N306RM8 in my 2017 Forest River Cherokee Wolf Pup. Seem to be plagued by carbon boogers building up on the flame probe running on LP. What causes them? Replaced the burner tube/orifice about a year ago. Recently replaced New Flame probe as it was burned up. Today replaced burner tube / orifice again with a new one to see if that corrects the issue. It seems when there is carbon build up on flame probe the refrigerator does not cool as effectively while running on LP.
Thank you,
Ken

[KenS999]

Update on norcold refrigerator flame probe vcarbon buildup. I replaced the rubber hose from the regulator to the propane bottle as it had some cracks in it. I removed the baffle from the chimney. It was clean. Water column pressure was checked and set to 11. Flame is blue and not Yellow on burner. Still getting carbon buildup on flame meter probe? When carbon buildup is removed from flame probe then refrigerator cools better.Not sure what else I can check. Cooling unit works very well on electricity. Any recommendations would be appreciated. Thanks, Ken

[KenS999]

Thank you that was a great article with illustrations on an RV fridge. Illustration looks quite similar to my norcold burner/flu setup. Still getting a buildup on the flame meter probe even after correcting the WC pressure to 11. Next step was to try addressing any blockage in the flue tube. Was unable to get the cap off the flue tube. Ended up rapping on the tube at the top and bottom to try and free up any buildup. Then blew a little compressed air down the top of the flue pipe with the burner vents covered. Really didn't seem to get any residue out of there. When I get to permanent shore power and am running on electric again, I will wrestle with getting that flue tube cap off and figure out how to remove that baffle. Not much clearance in that workspace
as it is down below eye level unfortunately. Will report back on what I found. Thanks. -Ken

[dougrainer]

KenS999 wrote:
WC pressure was at 12 inches, so I turned it down to 11. I will monitor it now and see if I continue to get carbon build up on the flame meter probe.
Thanks.

WC is set at 11.5. Doug
PS, the correct way to check is to connect the Manometer AT the refer and see what the pressure is at the refer when running.

[KenS999]

WC pressure was at 12 inches, so I turned it down to 11. I will monitor it now and see if I continue to get carbon build up on the flame meter probe.
Thanks.

[dougrainer]

KenS999 wrote:
Question, can I blow compressed air up the exhaust flue to clean it? My flue does not go up to the roof but exhausts out a upper vent. It's only about two and a half feet long but not sure how to disassemble it. Would rather not if I don't have to. Thanks.

This is great. Remove the upper door and remove the baffle. It is on a long metal wire and just pulls up. Doug

https://escapees.com/rv-refrigerator-part-2-lp-gas-operation/

[wa8yxm]

Generally on a propane appliance it is correct there is no "Fuel Adjustment Screw" Like there is on a gasoline carburetor.

What there is an air adjustment slider This is OFTEN (But not always) a window in the large tube past the oriface with a slider over it.. If you are running rich you slightly loosen the screw open the window a bit more (Then tighten the screw) if running lean you Same procedure but close it a bit.. Slide it open/closed till you get the best flame.. If you do not know how seek professional help.

I grew up with propane so have done several adjustments over the decades.

[KenS999]

Question, can I blow compressed air up the exhaust flue to clean it? My flue does not go up to the roof but exhausts out a upper vent. It's only about two and a half feet long but not sure how to disassemble it. Would rather not if I don't have to. Thanks.

[KenS999]

Thank you.

[dougrainer]

KenS999 wrote:
"Make sure your flame is not yellow, lastly adjust your flame fuel screw if everything else is clear."

Thanks. Flame is blue. Where is this fuel screw that you mentioned located at? Burner tube/orifice is a single piece, and brand new. Ken

There is no fuel adjustment screw. I would remove the orifice and make sure it is not partially blocked. I would blow compressed air UP the burner tube to clean it out. If the refer is in a slide room you can remove the burner baffle from the upper vent door. Otherwise you will have to pull the refer to verify Burner baffle and no debris. An EASY check of a regulator without a Manometer is to light the range burners(all 3 or 4). Then run the water heater on LP and the Furnace. IF the range burner flames rapidly pulsate up and down or diminish, your regulator is BAD. Replace it. Doug

[ScottG]

C Schomer wrote:
Id checked the gas pressure too. If the pressure is low, the btu input will also be low but it will also draw in less primary air. A dust free, clean orifice is also important, but that doesn’t sound like it would be a problem in your case. Be sure the burner is super clean, so nothing restricts the primary air intake.
If it still soots after all that cleaning Id figure out a way to get more primary air… by hook or by crook, there are ways. Craig

Good idea. I had suspicions about my pressure so I built a manometer and found that my reg not only wasn't regulating, it would drop to 10" with more than one appliance running - the the reg was only 4 y/o!
A new American made regulator has everything running perfectly.

[KenS999]

"Make sure your flame is not yellow, lastly adjust your flame fuel screw if everything else is clear."

Thanks. Flame is blue. Where is this fuel screw that you mentioned located at? Burner tube/orifice is a single piece, and brand new. Ken

[C_Schomer]

Id checked the gas pressure too. If the pressure is low, the btu input will also be low but it will also draw in less primary air. A dust free, clean orifice is also important, but that doesn’t sound like it would be a problem in your case. Be sure the burner is super clean, so nothing restricts the primary air intake.
If it still soots after all that cleaning Id figure out a way to get more primary air… by hook or by crook, there are ways. Craig

[eHoefler]

You are running rich, not enough oxygen. Check the full length of the burner tube and chimney. Make sure it is clear of wasp nest and spider nest. Make sure your flame is not yellow, lastly adjust your flame fuel screw if everything else is clear.