Refrigerator issues, need help troubleshooting

RyanBoz46 · 02-16-2021, 03:08 PM

Hello everyone. New here, Just bought a 2020 Talon 403T.
The issue:
Dometic RM1350SL 4 door fridge
-On the road trip home from buying it the fridge quit working (no cooling, fridge or freezer, digital display on front would flash then shut off)
-I removed the rear access panel and found the fridge control board just hanging there by the wires, not mounted to the back of the fridge.
-After reviewing the wiring diagram I found that the mounting tab on the control board serves as the ground point as well, so since it was just hanging there, ungrounded, it found a ground within itself and burned up.
-I called the dealership where I bought it (Houston, TX... I live in CA) and told them what I found and they told me that they had already replaced the control board once, so there must be an issue with the fridge itself.
-I told them that they did not install the board properly and it burned up so they agreed to send me another control board.
-I installed the new control board and it began to work properly.... for 1 trip.
-Now it has failed again. But this time it will turn on and I can hear the propane light up but it will not get cold, the last time I tried it actually got WARMER inside, from 55 to 60.
-It will not work in Auto mode or LP mode, nor when connected to shore power or just running off 12v.
-It turns on, but no cooling, and I can hear a fan running periodically.
-I've inspected the wiring but found no obvious issues.
-YES the RV is level

If anybody has some troubleshooting tips I'd be grateful because the next available warranty service appointment is 1 month from now.

Thanks!

Grumpy · 02-16-2021, 03:44 PM

Your best bet is to call DOMETIC directly (800) 701-2944

RyanBoz46 · 02-16-2021, 03:55 PM

Grumpy,

I that didn't even cross my mind but it's a good idea, I'll give it a shot.

Thanks

JimD · 02-16-2021, 04:58 PM

Attached is my troubleshooting guide with a big section on fridges. Take a look.

Scottenj · 02-16-2021, 05:30 PM

Dometic has a service manual for that refrigerator with a trouble shooting guide available here: https://bryantrv.com/docs2/docs/Serv...,%20RM1350.pdf

RyanBoz46 · 02-19-2021, 10:18 AM

Thanks for the manuals.

-Thermofuse tested good
-Confirmed 110v through cooling unit heating elements, and measured a resistance of 34 ohms.
-All power supplies and grounds are present
-Propane side, igniter works, flame starts

I tested the thermistor at room temperature and after sitting in ice water and found an open circuit/no ohm return.

I was confident I had found the issue so I replaced the thermistor and turned the fridge on last night. Came out this morning to check and found it still at 60F(on display) and in fact the inside of freezer feels WARM.

Could a failed thermistor take out the control board?

Any other ideas?

Thanks

RyanBoz46 · 02-19-2021, 10:21 AM

Ah,

One thing I forgot to mention, when testing the voltage on the heater element wiring at the circuit board one of the legs sparked when I wiggled it due to a poor connection between the pin and the connector. So I tightened all the connections but I am hoping that the loose connection didn't somehow cause the control board to overheat and fail.

JimD · 02-19-2021, 10:33 AM

Quote:

Originally Posted by RyanBoz46

Thanks for the manuals.

-Thermofuse tested good
-Confirmed 110v through cooling unit heating elements, and measured a resistance of 34 ohms.
-All power supplies and grounds are present
-Propane side, igniter works, flame starts

I tested the thermistor at room temperature and after sitting in ice water and found an open circuit/no ohm return.

I was confident I had found the issue so I replaced the thermistor and turned the fridge on last night. Came out this morning to check and found it still at 60F(on display) and in fact the inside of freezer feels WARM.

Could a failed thermistor take out the control board?

Any other ideas?

Thanks

Very doubtful that the thermistor could take out the board. It is basically just a resistor. The board should be designed to tolerate an open or dead shorted thermistor without blowing itself up.

The thing to look for is whether the unit is trying to cool or not. If the burner is on, it is trying to cool and this takes the thermistor out of the equation because the board is reading the thermistor and is saying things are too warm and activates cooling.

If it is trying to cool but not getting anywhere on both gas and electric, you probably have a problem with the actual cooling unit. Clogged, leaked ammonia, whatever. It might be time to have a pro take a look.

RyanBoz46 · 02-19-2021, 10:44 AM

Quote:

Originally Posted by JimD

Very doubtful that the thermistor could take out the board. It is basically just a resistor. The board should be designed to tolerate an open or dead shorted thermistor without blowing itself up.

The thing to look for is whether the unit is trying to cool or not. If the burner is on, it is trying to cool and this takes the thermistor out of the equation because the board is reading the thermistor and is saying things are too warm and activates cooling.

If it is trying to cool but not getting anywhere on both gas and electric, you probably have a problem with the actual cooling unit. Clogged, leaked ammonia, whatever. It might be time to have a pro take a look.

Thanks for the reply Jim.

From your advice it sounds like I can put the fridge into LP mode and if the flame lights and continues to burn the logic would say it is trying to cool so the electrical side is OK meaning a problem with the cooling unit

Or

If the flame does not continue to burn it could mean an electrical and/or circuit board problem.

I will test this theory tonight.

If it is a cooling unit problem that would leave me confused because of the history:
The dealership replaced the control board before I bought the unit (I don't know why) but the fridge was working when I took delivery.

I found that they installed the board incorrectly and it burned up so I replaced it again and the fridge started working again but failed after 1 trip.

If the cooling unit was bad, why would it work after both new boards were installed?

JimD · 02-19-2021, 11:04 AM

Definitely a strange problem. These things are basically binary in cooling operation - all ON or all OFF. There is no partial cooling. This means that if the board calls for cooling and STAYS in that mode, meaning the flame stays on or the electric element stays energized, the cooling should take place.

If the board turns the cooling on and off then there could be a board problem. The heating, whether gas or electric, causes the ammonia in the tubing to boil and flow through the tubing. At some point in its flow it removes heat from the fridge and then expels it out the back at some other point in the flow.

Think of the thermistor/board part of the equation as a simple on/off switch. When on, the cooling is full tilt on and when off, it is totally shut down.

RyanBoz46 · 02-19-2021, 11:17 AM

With the info you've given me it should be easy now to isolate which system is at fault at least, electrical side or cooling unit. Bottom line is if the flame is burning or the heating elements are active and its not cooling there is an issue with the cooling unit.

I will test it tonight

Jeffur · 02-19-2021, 12:19 PM

Check for signs of ammonia leak, smell or yellow powder. Make sure the vent passage way on the back is unobstructed. Adding a couple of fans here helps improve the cooling capacity of the condensor. Make sure the center mullion flapper and fridge door gaskets are closing, meeting and tight. If all else fails - and you can still confirm the fridge is trying to cool (unit running continuously to attempt to cool) - then it’s time to burp the fridge , if that last ditch effort doesn’t get it - it means time for a new fridge.

SmokerBill · 02-19-2021, 12:35 PM

This article might be helpful.

The RV Doctor: RV Absorption Refrigeration - Cooling Unit Facts, Faults and Fixes

RyanBoz46 · 02-20-2021, 11:04 AM

I let the fridge run on LP last night for about 5 hours. Constant clean flame burning the whole time and the temperature didn't budge from 60F. Based on the info from this thread it looks like I'm in need of a cooling unit. It is still under warranty so there's no cost but I am not excited about how long it might have to be at the shop based on stories I've heard about service times.

Jeffur · 02-20-2021, 01:06 PM

Burp the fridge

RyanBoz46 · 02-20-2021, 01:13 PM

Quote:

Originally Posted by Jeffur

Burp the fridge

Doesn't that require removal of the fridge and turning it on it's side or upside down?

If I didn't have a warranty I would consider that, but I'm not going to get that deep into it when I can have it fixed for free.

mlumia · 02-24-2021, 03:00 PM

Hi,

Sounds like you are still under warrantee so getting it fixed under that would be your best bet.

That said do check out the troubleshooting videos on My RV Works - Darren is super thorough and breaks down complex issues into step-by-step logical troubleshooting. I have resolved many issues over the years referencing his videos. He does have some specific videos on Dometic frigs

Home site: https://myrvworks.com/
General YouTube Channel:
https://www.youtube.com/channel/UCoK...ZLCD3flLXZVQvw

Oh he also has just about every user + technical manual posted on his home site here: https://myrvworks.com/manuals/

Best of luck

PA Nate308 · 02-25-2021, 06:21 AM

I have a 2021 Talon 403T. My rig is heading to the dealer for the third Dometic two door fridge. Its under warranty and they keep replacing it but there is obviously a problem. The dealer says this is a 4,000$ replacement. So I’m at 12,000$ for a fridge. At this point I have zero confidence in this fridge. I’ve camped without a working fridge more than I’ve had one that works.. It’s so bad, I’ve placed a small fridge in the garage for back up..

JimD · 02-25-2021, 12:08 PM

Quote:

Originally Posted by PA Nate308

I have a 2021 Talon 403T. My rig is heading to the dealer for the third Dometic two door fridge. Its under warranty and they keep replacing it but there is obviously a problem. The dealer says this is a 4,000$ replacement. So I’m at 12,000$ for a fridge. At this point I have zero confidence in this fridge. I’ve camped without a working fridge more than I’ve had one that works.. It’s so bad, I’ve placed a small fridge in the garage for back up..

I am guessing that they replaced the fridge due to a problem with the cooling unit. Since this is a recurring issue, have they checked that the installation area meets the manufacturer specs? This and operating the unit way off level is the only thing I know that can damage a cooling unit.

I was told this a long time ago when my camper's fridge had a problem and they found out that it hadn't been installed properly.

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