Dometic RM3863 refrigerator

[cpn_dick]

Having problems with 3 way fridge. Currently on A/C power and with auto button depressed it cools great for a couple of days then switches to gas and then malfunctions. When auto button is up runs for a while on gas, sometimes a day or 2. Then goes to check. Doesn't cool on d/c. I think it may be one of the control panels but don't know which. Does this ring a bell for anybody? Could it be corrosion or ground problem?
You guys were a great help on my other problem with the batteries. I replaced the batteries and the converter and fixed it.
This is in a 1988 Overland, which I love.
Thanks.
Dick

[Dog_Trainer]

dougrainer wrote:

cpn dick wrote:
OK thanks guys I have changed the board to the Dinosaur from PPL. Now the controls all work , stays on ac, but the refer. doesn,t cool. been on for 24 hours, the a/c element is hot but no cooling. How do I test the thermister. Dinosaur says that if the thermister tests then I might need a thermister adjuster.
Thnaks for the tip on thr $89 deal.
Dick

You do NOT test the Thermister. You wire the 120 element DIRECT to 120 power for 24 hours. IF the refer does NOT get below 40 degrees and below 10 degrees in the freezer, your Cooling Unit is bad. Doug

Great advise again from Doug I might ad that you should check the freezer part vs the fresh food area. When mine acted up I had great cooling in the freezer and not much in the fresh food. As doug suggests you need to direct wire the element to 120 and see if it cools. When I had my trouble same refer as you I called dinosaur direct he sold me the board and another part I forget the name and then he walked me through the adjustments on the other part I just can't remember all the details as it has been a couple of years.

[dougrainer]

cpn dick wrote:
OK thanks guys I have changed the board to the Dinosaur from PPL. Now the controls all work , stays on ac, but the refer. doesn,t cool. been on for 24 hours, the a/c element is hot but no cooling. How do I test the thermister. Dinosaur says that if the thermister tests then I might need a thermister adjuster.
Thnaks for the tip on thr $89 deal.
Dick

You do NOT test the Thermister. You wire the 120 element DIRECT to 120 power for 24 hours. IF the refer does NOT get below 40 degrees and below 10 degrees in the freezer, your Cooling Unit is bad. Doug

[cpn_dick]

OK thanks guys I have changed the board to the Dinosaur from PPL. Now the controls all work , stays on ac, but the refer. doesn,t cool. been on for 24 hours, the a/c element is hot but no cooling. How do I test the thermister. Dinosaur says that if the thermister tests then I might need a thermister adjuster.
Thnaks for the tip on thr $89 deal.
Dick

[dougrainer]

cpn dick wrote:
I hope I'm replying to your suggestions in the right place. New to forums. Wanted to say I appreciate the thoughts. The circuit board is a very light beige, almost cream colored.As suggested by Doug. Should I get it bench tested or just replace it?
I will clean and tighten all the contacts and grounds before I do either. Thank you ,I will post the results when I have them.
Dick

Bench testing will show it is OK. Back in the early to mid 90's Dometic had thousands of Intermittant control boards. Besides the date code on them, the tell was that beige/creme colored Epoxy. They would intermittantly show "check" even if the refer never tried to light on LP. That is why I asked the color. No need to EVER go any further on a Diag of a Dometic refer if you have the Beige colored board. Replace the board with the current style and that eliminates the problem with the bad boards. The replacement boards have a kind of bright green epoxy from about 1998 on. Doug

[Old-Biscuit]

cpn dick wrote:
I hope I'm replying to your suggestions in the right place. New to forums. Wanted to say I appreciate the thoughts. The circuit board is a very light beige, almost cream colored.As suggested by Doug. Should I get it bench tested or just replace it?
I will clean and tighten all the contacts and grounds before I do either. Thank you ,I will post the results when I have them.
Dick

Doug is an RV Tech (30 yrs.) and knows his stuff.
As suggested.......replace that old board

PPL Dometic Dinosaur Board for your fridge.....LINK

[cpn_dick]

I hope I'm replying to your suggestions in the right place. New to forums. Wanted to say I appreciate the thoughts. The circuit board is a very light beige, almost cream colored.As suggested by Doug. Should I get it bench tested or just replace it?
I will clean and tighten all the contacts and grounds before I do either. Thank you ,I will post the results when I have them.
Dick

[1BryNelson]

So with having replaced bats recently your 12v dc should be good source. Check all connections from fuse to refer. My guess is you lost a circuit board in the fridge.
If still available for '88, new $200 to $400. Might find used fridge less expensive.
Good luck, keep us up to date.
Bry.

[dougrainer]

Take the Black cover off of the Main control board on the outside back of the refer. IF the circuits are mounted in beige/color resin, your Main board is defective. Replace it. The board, if this color, has either been replaced in the mid 90's or never replaced. Doug

PPL HAS THEM ON SALE FOR $90

[Old-Biscuit]

In auto on electric and then swaps to gas........that's due to loss of AC power
Runs on gas then 'check' light..that's due to loss of flame/won't light
Doesn't cool on DC......that could be a bad DC electric heat element

BUT ALL problems could be faulty DC power.......
Good 12V DC power is needed. Doesn't take much corrosion/bad connections to stop 12V DC.

Check for obvious bad connections on lower board.
Check ground connections clean & tight

Lower control board/module is the main power board.
Pull it and have it checked at an RV repair shop on a bench board tester