Bounder: Dometic fridge issues.

[1ramblingman]

So we just bought our 2012 35K and are going through everything before we hit the road. One of the things that needs addressed is the fridge. On AC, freezer cools to 3 degrees F and the fridge cools to 33/34. Switch to gas, the freezer stays put but the fridge warms up to over 42, might go higher but I switch back to electric at that point. When we bought it, it wouldn't run on gas and wouldn't even try to ignite. Tore into it and found a chunk of ash or something between the igniter and the gas port so that was blocking the spark. Looked like there had been some pine needles or something in there and was a small pile of ash, about the size of my palm. Wondering if the burner was damaged somehow and isn't getting hot enough or if this model would work better with a fan to circulate the air better? I called Dometic and they're stumped... The model is RM1350. Any help would be greatly appreciated. Thanks for reading.

[TXiceman]

Have you cleaned the burner? They generally operate better on gas than electric.

The biggest issue on these RV fridges is air circulation. I generally add one or two more 12-volt fans in the outer compartment to help the cooling and a small 12-volt fan in the interior to air in circulation.

Over the years, these units have dropped in quality and typically have a service life of 7 to 10 years.

Dometic and Norcold are generally clueless for help with these units

Good luck.
Ken

[saddlesore]

As has been said , You may be reaching the end of the OEM planned lifespan..

That said , You may want to research for updated propane innards or convert to a compressor style innards. using Your existing fridge.
https://jc-refrigeration.com/

[Old-Biscuit]

Good grief.
Cooling unit functions GREAT.....AC shows that with the temps reached

LP......need to thoroughly clean the burner, orifice, flue etc
Dirty burner assembly can NOT generate/transfer sufficient heat to sustain properly cooling. Only boiling enough ammonia to cool freezer section...not enough absorption left to cool food compartment

AC Works.....LP doesn't ===Clean up the burner assembly

See pgs 31 & 32
http://bryantrv.com/docs2/docs/Servi...,%20RM1350.pdf

[Jim_HiTek]

One other thing...when on gas, there is a very low resistance probe/spark assembly that is supposed to sense when the flame is on and act accordingly. IF the terminals from/to that device are loose, then the control circuit could snuff off the flame, try to re-spark it, and repeat. So check those terminals that go to the control card, they should NOT be loose at all, squeeze them with pliers if needed. Also, cleaning and lightly sanding that spark/sensor device helps too. And your Users Guild will tell you what the gap should be set at.

And the comment that absorption refers only last 7 to 10 years ONLY applies to those that camp near the ocean, then drive home and leave the refer (along with the RV) without power without spraying down the coils. Spray down the coils, or always have the refer powered and they'll last up to 70 years. The heat produced by the refer running will keep the coils from developing rust, which often causes leaks over time. And 7-10 years is common for those situations where people camp at the beach, come home, empty the refer and leave the RV unplugged and the refer without power. What they should do is keep the refer running, spray the coils, let them thoroughly dry, (maybe for days depending on local weather conditions) before turning them off.

[emcee]

Originally Posted by Old-Biscuit

Good grief.
Cooling unit functions GREAT.....AC shows that with the temps reached

LP......need to thoroughly clean the burner, orifice, flue etc
Dirty burner assembly can NOT generate/transfer sufficient heat to sustain properly cooling. Only boiling enough ammonia to cool freezer section...not enough absorption left to cool food compartment

AC Works.....LP doesn't ===Clean up the burner assembly

See pgs 31 & 32
http://bryantrv.com/docs2/docs/Servi...,%20RM1350.pdf

The gas pressure should also be verified (low pressure = soot)

[Old-Biscuit]

Originally Posted by Jim_HiTek

One other thing...when on gas, there is a very low resistance probe/spark assembly that is supposed to sense when the flame is on and act accordingly. IF the terminals from/to that device are loose, then the control circuit could snuff off the flame, try to re-spark it, and repeat. So check those terminals that go to the control card, they should NOT be loose at all, squeeze them with pliers if needed. Also, cleaning and lightly sanding that spark/sensor device helps too. And your Users Guild will tell you what the gap should be set at.

And the comment that absorption refers only last 7 to 10 years ONLY applies to those that camp near the ocean, then drive home and leave the refer (along with the RV) without power without spraying down the coils. Spray down the coils, or always have the refer powered and they'll last up to 70 years. The heat produced by the refer running will keep the coils from developing rust, which often causes leaks over time. And 7-10 years is common for those situations where people camp at the beach, come home, empty the refer and leave the RV unplugged and the refer without power. What they should do is keep the refer running, spray the coils, let them thoroughly dry, (maybe for days depending on local weather conditions) before turning them off.

OPs RM1350 has a Spark Electrode for High Voltage Ignition but uses a Thermocouple for Flame Sensing
*overtighting thermocouple connection will damage it
OP just needs to clean up the burner assebmly

[Fridge Defend]

Originally Posted by 1ramblingman

1) On AC, freezer cools to 3 degrees F and the fridge cools to 33/34. Switch to gas, the freezer stays put but the fridge warms up to over 42,

2) might go higher but I switch back to electric at that point. When we bought it, it wouldn't run on gas and wouldn't even try to ignite.

3) Wondering if the burner was damaged somehow and isn't getting hot enough

4) or if this model would work better with a fan to circulate the air better?

Sounds like you have a handle on cleaning the burner assembly, be sure to clean the flue tube and inspect the spiral diffuser within the flue tube. The burner should not be damaged by debris, just clean it up.

1) Good on you, this is good info, it sounds like you have isolated the issue to LP Gas operation issue.

2) If the fridge is not working properly on LP Gas mode, try not to use it until you find the issue. This is because the fridge is not producing enough refrigerant when in the LP Gas mode of operation, this overheats the boiler.

3) Yes, moving on from last answer, as mentioned above, start by checking your gas pressure to make sure that the propane system regulator is keeping the system pressure at 11 inches of water column, do a load test by turning on your gas burner on the stove top to check to see the flow. As a rule of thumb you should not see much more than 0.5" H2O change in pressure.

There is a port on the side of the burner, you can request a link to a photo if you like. Once you confirm your system pressure, check the pressure at the burner jet. If the pressure is low here, then you have a plugged LP filter, again we show how to clean on our site.

Lastly, take out the burner jet and hold it up to the light, it may have contamination in it, clean with 90% isopropyl alcohol and gentle air pressure. Some times it is just best to get a new jet.

4) We engineered a fan controller that our customers rave about, for the Dometic 1350 and Norcold 1200 and 2118 series of fridge we have spectacular results. These larger fridge struggle when ambient temperatures are over 90degF.

Hope this helps

[1ramblingman]

[ATTACH][/ATTACH]

Great info and thank you everyone! I am showing a couple of pics BEFORE I cleaned everything but after reading the replies, going to take it all apart and give it a much deeper cleaning. Didn't know I could clean the burner and now I know I need to get up into the flu also. Might just replace it all. I don't have any way to measure the pressure of the gas. From what I found from Dometic, there should be two fans up by the fins and I haven't heard them running at any time if there are fans up there. If there aren't will definitly look into getting some and if there are, make sure they're running and add more if needed. Will update as things develop and thanks again!

[Old-Biscuit]

Your Picture shows more cleaning needed BUT also one important component is MISSING

The Thermocouple that senses flame and generates milliamp signal to keep gas valve solenoid open
W/O that thermocouple gas flame can not remain lit....hence the rise in tempds
*It goes thru that large hole in burner bracket above the burner so flame engulfs it
***Leads from thermocouple plug onto circuit board terminals J4 & J9

Link provided in post #4


Fridge Also has 2 thermostat controlled fans on exterior
Thermostat is connected to Condenser FIN far right.
DC Power goes to/thru T-stat to fans
T-stat closes at 149*F +/- FIN temp to start fans and opens at 122*F +/- Fin temp to stop fans

Also in Link provided

[1ramblingman]

I'm going to be tearing back into it tomorrow. I'm surprised becuase the flame does stay lit for sure but clearly missing the thermocoupler and while the burner is lit and running, the fridge temp continues to rise. The pics are before I cleaned everything up. Looks like there is much digging needing done on this and also looks like I need to take the entire top vent on the roof to check the fans and look for any other debris. The other day I pulled the cover off the roof area and there was a screened area under that which had a bunch of pine needles on it that I cleaned off. Great info and nice that you spotted the missing part! Thank you!

[Old-Biscuit]

RM1350 Series

2 Different Circuit Boards were used depending on Production Numbers

This is what one of Dometic Board looks like (thermocouple)


This is what the other Dometic Board looks like (NO thermocouple)


Post a picture of your current circuit board..........

[Fridge Defend]

Originally Posted by Old-Biscuit

Your Picture shows more cleaning needed BUT also one important component is MISSING

The Thermocouple that senses flame and generates milliamp signal to keep gas valve solenoid open
W/O that thermocouple gas flame can not remain lit....hence the rise in tempds
*It goes thru that large hole in burner bracket above the burner so flame engulfs it
***Leads from thermocouple plug onto circuit board terminals J4 & J9

Link provided in post #4


Fridge Also has 2 thermostat controlled fans on exterior
Thermostat is connected to Condenser FIN far right.
DC Power goes to/thru T-stat to fans
T-stat closes at 149*F +/- FIN temp to start fans and opens at 122*F +/- Fin temp to stop fans

Also in Link provided

I converted my original thermocouple type board (P-711) to the 'integrated igniter' board on my 1988 Dometic. It takes some wiring changes, but works fine. Look for the igniter coil on the board you have, also, if the igniter wire goes to the main board, then it has been converted.

Hope this helps

[1ramblingman]

Digging into it today and noticed black soot around different areas which looked like fuel not being completely burnt. Was able to get my camera under the tube the baffle is in and I don't think this is helping at all. Haha. This would also explain the strange odor I would smell in the cabin when running on propane and heat not getting all the way up. I have the burner jet and tube soaking in alcohol and know the next step is to remove the flue baffle and get all that gunk cleaned out but for the life of me, I can't see how to do it without pulling the fridge. Is there a way to do it without pulling the fridge? I've looked online and can't find any videos showing how to do it. In looking all this over, It's amazing this coach isn't sitting in a wrecking yard completely burned up.
Also, the cirquit board is the second one, the one in the black plastic.
Just a side note, as I cleaned the tube out from the bottom, the flue baffle feels like it's spring loaded or something. I can push it up and it has resistance and pushes itself back down.