Dometic RM2852 fridge wont stay lit ?

[tri5ron]

Hello All,
It's been a LOOOooonnnnggg time since I've been around here, but Open Roads Forum has always been my "Go-To" place when I need to get knowledgeable experienced advise... so here I am.

I now live in a senior citizens community, and I "hang out" at the RV Storage Lot here within the community. Being that many of the citizens here are on limited incomes, and/or not able to do all of their own maintenance on their rigs, I am often asked to help them out.

I do have some past experience with RV fridges not working properly, and I have a (very basic ) knowledge of both their function and common problems. I have had to replace the circuit board on a couple of rigs over the years, using the "Dinosaur Brand" purchased from Randy at BestConverter.com. These worked quite well for those repairs.

Ok, so here's what I have so far.

The senior citizen owner of this fridge, Dometic RM2852, tells me it would not self light when switched to propane... but he could get it to light using a long BBQ lighter.
It would stay lit for several hours, but at some point it would shut off and the "check" light on the control panel would then come on.
I have verified that this is what happens.
First I went to check for carbon build up at the igniter and did find some carbon there causing a weak spark.
I removed the build up,... shut off the fridge,... turned it back on,... and it lit at first spark. YAY ! I thought I was "out of the woods" that easy, but unfortunately, that does not seem to be the case.

When it did light, it ran for several hours, (overnight actually), and yes it did get plenty cold inside the fridge. All seemed well, but then at some point it will shut itself off and not re-light. (no self sparking from the igniter). "check" light comes on and stays on.

The propane tank is full, and yes I have fully checked and verified there is no spider webs of other blockages in the gas/air tube.
When is WAS burning,... I was getting a nice clean Blue flame. no problems there.
It just decides at some point to shut itself off.
We at at sea level, and there has not been any wind blowing it out. so it's not that either.

I called Randy, and He does not think it is the circuit board,... I also just got off the phone with Dometic Customer Service. I spoke with a nice lady there "Nina", who also thinks it is not the circuit board.
Nina checked with somebody else there, (I'm assuming another service technician), who also does not think it is the circuit board.
They suggested a possible DC 12v signal problem going TO the circuit board,... and suggested that I check, clean, and re-apply Dielectric grease to all connections in the electrical system supplying the fridge.
I have done this to all the connections on the board itself,... but not beyond that yet. But to be honest,... I'm fairly confident there is not an issue with electrical power supply going TO the fridge.

Nina also suggested the possibility of it being,(this is a quote), "the electrical component with the porcelain insulator".
I asked her if she meant the "Thermal coupler", and she replied "No,...that model fridge does not have a Thermal sensor".

That does not sound correct to me,
but maybe it is ? ? ?,... I dunno.

SOOoooo,... I figured I'd "Go running home to Momma", (i.e.- come to all you knowledgeable folks with my questions.

I'm trying to help out a friend here, and hopefully avoid having him go spend $$$ needlessly. He lives a Very modest life on a VERY limited income. He does not have the luxury of just taking it to a RV Dealership every time there is a glitch in his giddy-up.

So what say all of you ?
What do you think would be causing this periodic shut down when running on propane ?
What would you check next ?

I have not yet checked "the porcelain insulated electrical component",... but I still think that is the thermo-couple which tells the controller "Yep, the flame is still lit".
Maybe I'm wrong there,... but if it IS the thermo-couple,.. and the fridge DOES run for several hours before shutting itself off,... then doesn't it stand to reason that the thermo-couple is still operating properly ?

Any advise and replies are greatly appreciated.
Thanks for taking the time to read this long post.
Cheers,
Ron

[trailrider]

enblethen wrote:
If you leave it connected, any problems in circuit board can affect the readings. here is video of testing old style.thermal couple testing

Well I guess you are smarter than Dometic who manufactured the refrigerator and wrote the service manual I linked above.

[enblethen]

If you leave it connected, any problems in circuit board can affect the readings. here is video of testing old style.thermal couple testing

[trailrider]

Wrong again. You test the thermocouple with it connected to the circuit board. From the manual I linked above:

THERMOCOUPLE . .
The thermocouple should produce 25 to 35 millivolts when connected to the lower circuit board. Any
reading below 18 millivolts could cause erratic gas operation.

To check the flame sense circuit of the lower circuit board, measure the millivolts between J3 terminal
and the other wire connection from the thermocouple. The millivolt meter should read between 25
to 35 millivolts with the gas flame burning. Turn the manual shutoff valve to OFF and watch the
millivolt reading as it drops. Note the millivolt reading when Plug 3, terminal 4 (blue wire) receives
power. It should be 10 plus or minus 3 millivolts or 7 to 13.

[enblethen]

I had a brain fart on style of thermal couple.
OP: you can test the thermal couple using a multi meter eqyuiped with millivolt scale. Disconnect the thermal couple from circuit board, attach meter leads to thermal couple wires, use long lighter to place flame diretly on thermal couple. Thermal should produce 30+ millivolts.

[trailrider]

tri5ron wrote:

Old-Biscuit wrote:

tri5ron wrote:
Thanks for all this info so far. You guys are great.
The product number for this fridge is
921146004.

I probably won't get back to the fridge until tommrow or over the weekend.

Then it has a thermocouple for flame sensing AND a spark electrode for ignition

Thermocouple has to sense the flame lit otherwise the circuit board shuts down DC to Gas Solenoid so raw fuel doesn't accumulate in burner area

Thermocouple tip MST be engulfed in flame when it lights off
Thermocouple MUST be clean...no soot/carbon build up
Thermocouple MUST have a clean/tight connection
Thermocouple should produce 25-35 Millivolts to lower board when heated (Lower then 18 millivolts will cause erratic flame operation)

Thank you for the info,
I have not been able to get back to this thread (or the fridge) until now.
I will go check to see if there is carbon build up on the thermocouple and that it is engulfed in flame (if I can get it to relight now).

If that is not it,... Can anyone tell me m
Where to order the parts from ? Possibly provide any part numbers ?
Thanks

You need to study this: http://appliance911seabreeze.com/RM2852_RM2612_RM2812_RM2652_Service_Manual.PDF

It sounds like that fridge has a re-igniter that provides the spark for the electrode to light the burner and it also senses the flame when lit and stops the sparking. Flame blows out it sparks and re-ignites the flame. Re-igniter is bad or isn't getting 12 volts from the circuit board to operate. https://www.amazon.com/Dometic-2931132019-Re-Igniter/dp/B00BTL7P5M

Parts List: http://www.laurelhurstdistributors.com/parts/refrigerators/dometic/RM2852_1.html

[trailrider]

enblethen wrote:
thermocouple at Ace
Take your old one out to verify length and style of mount.

That won't fit that fridge. This is the type that fits that fridge:
https://www.amazon.com/MC-Enterprises-2932052018-Thermocouple/dp/B00C5TEV40

[enblethen]

thermocouple at Ace
Take your old one out to verify length and style of mount.

[trailrider]

enblethen wrote:
Thermocouple should be available at most hardware store.
Amazon is your friend along with ebay.

You won't find a thermocouple that will fit that fridge at a hardware store.

[enblethen]

Thermocouple should be available at most hardware store.
Amazon is your friend along with ebay.

[tri5ron]

Old-Biscuit wrote:

tri5ron wrote:
Thanks for all this info so far. You guys are great.
The product number for this fridge is
921146004.

I probably won't get back to the fridge until tommrow or over the weekend.

Then it has a thermocouple for flame sensing AND a spark electrode for ignition

Thermocouple has to sense the flame lit otherwise the circuit board shuts down DC to Gas Solenoid so raw fuel doesn't accumulate in burner area

Thermocouple tip MST be engulfed in flame when it lights off
Thermocouple MUST be clean...no soot/carbon build up
Thermocouple MUST have a clean/tight connection
Thermocouple should produce 25-35 Millivolts to lower board when heated (Lower then 18 millivolts will cause erratic flame operation)

Thank you for the info,
I have not been able to get back to this thread (or the fridge) until now.
I will go check to see if there is carbon build up on the thermocouple and that it is engulfed in flame (if I can get it to relight now).

If that is not it,... Can anyone tell me m
Where to order the parts from ? Possibly provide any part numbers ?
Thanks

[Old-Biscuit]

tri5ron wrote:
Thanks for all this info so far. You guys are great.
The product number for this fridge is
921146004.

I probably won't get back to the fridge until tommrow or over the weekend.

Then it has a thermocouple for flame sensing AND a spark electrode for ignition

Thermocouple has to sense the flame lit otherwise the circuit board shuts down DC to Gas Solenoid so raw fuel doesn't accumulate in burner area

Thermocouple tip MST be engulfed in flame when it lights off
Thermocouple MUST be clean...no soot/carbon build up
Thermocouple MUST have a clean/tight connection
Thermocouple should produce 25-35 Millivolts to lower board when heated (Lower then 18 millivolts will cause erratic flame operation)

[tri5ron]

Serial number
83700010

[tri5ron]

Thanks for all this info so far. You guys are great.
The product number for this fridge is
921146004.

I probably won't get back to the fridge until tommrow or over the weekend.

[bigfootford]

Service and install manual:

http://bryantrv.com/docs2/docs/operating/2652operation.pdf

Thermocouple=yes!

Troubleshooting:

http://bryantrv.com/refcontrols.html

Jim