Dometic RM3604 LP not re-igniting

[Jvand]

Hello,

I have an old Lance camper with a Dometic RM3604 refrigerator. I’ve sort of refurbished the refrigerator and got it back up and running on AC and LP, but recently it’s started having an issue where it will not cycle on and off on Gas. It always starts on LP just fine, runs for a few hours, then I’m assuming it kills the gas since it hits the cooling target. When it tries to start back up it fails to ignite and lights up the check gas light. I’m stumped as to what can cause this issue, I’ve read the service manual for this fridge, and there aren’t any hints I can find for this situation. 

I’ve done the following repairs on it:

-new AC heating coil

-new re-igniter module

-new thermocouple

-cleaned orifice, flue, and burner tube

-cleaned/dielectric greased all the connector contacts

-replaced any crimp spade connectors that looked corroded

-verified good input 12V power (measured 13.7V)

[stevenal]

Sorry, I didn't see the last post due to the way the new platform orders the replies. Might be easier to replace the cooling unit than the fridge. https://rvcoolingunit.com 

[StirCrazy]

your spending a lot of time and money that doesnt seam to be working, another option is to call a reasonably priced moble repair place and see how much he would charge to diagnose the exact problem and/or fix it.  then you will know weather it is worth fixing or not.

for what its worth you didn't need three posts for this, one post would do.  this just makes it confusing...  

[Jvand]

I’m going to try a new board now and see if that resolves the re-igniting issue since I know all the components for LP are working properly. I know oftentimes calling a repair tech will get me a quicker answer, but I want to understand how my fridge works, hence why I posted her in the first place. 

I created 3 posts because they were all asking distinctly different questions. This one is specifically about lighting the LP. 

[Jvand]

I put in a dinosaur Micro p-246 plus and it fixed the problem. Problem was definitely caused by the Dometic circuit board. 

[opnspaces]

Awesome, glad you finally got it figured out.

[Jvand]

Turns out that didn’t fix the problem. The fridge ran on propane for 12 hours without a check light because the propane wasn’t able to cool it down to the set point. I tried it again with the temp control set to min (highest temperature set point) and the flame extinguished when it hit that set point. Then the check light came on soon after, which I’m assuming was when the fridge tried to re-ignite the flame. 

Still no resolution for this and I may just find a new fridge replacement since it seems like it’s running really inefficient if 12 hours of LP flame on couldn’t get it down to the fridge set point. 

[Jvand]

I bought a manometer and measured my LP gas pressure at the refrigerator gas solenoid (it had a test port plug I was able to remove and install the manometer fitting). Turns out my gas pressure was only 10inH20, but the service manual for the Dometic said to not let it drop below 11. 
I had recently installed a new propane regulator in the RV and wasn’t aware that the gas pressure could be adjusted. I fine tuned it with an adjustment screw on the regulator and now my pressure is at 11.5inH20. Fridge ran for 12 hours straight without shutting off, so it looks like it’s fixed!

[stevenal]

https://www.dinosaurelectronics.com/Dom_boards.htm 

I doubt 1 inch will make much difference. The OEM boards from this era were pretty crappy. I went through all the steps you did, with much frustration. The Dino board was an easy replacement, and lasted years until I sold my old camper. Learned about it from RV.net.

I see some cheap ones available new on Ebay.