Dometic Fridge Problem in a brand new unit

[sdtravis]

We have a 2021 Dynamax Isata 3 with a Dometic DMR-702 refrigerator that is acting up and could use some help from all of you experts on this topic. I have a request in to a warranty dealer to help with this, but did my own investigative work on this ahead of time in case they can't figure it out. (and dealer service is booked out months, so hoping to find a cure on my own and avoid the delay).

Here's the scenario: When refrigerator is on propane, the panel will eventually light up an error code and shut the refrigerator off. The error code is always the same -- two blinking lights, 1) LP AND 2) Temperature setting (important detail -- the error blinks whatever the setting is currently set to, not a specific LED). The troubleshooting manual calls out a series of error codes, but given that the LP light flashes AND the temperature led flashes, I'm thinking this is the warning condition where LP is not lighting.

This condition is not easily repeatable, and it oddly happens in the middle of the night, also when unplugged from shore power. When turning fridge off and on repeatedly it will relight flawlessly.

Fridge works on AC, no issue.

Batteries are 99% SoC throughout the night, BMV shows no voltage drop or issues.

Propane tank is full. Other gas appliances work perfectly.

Original thermal cutoff fuse has continuity.

Original thermistor tests resistance in spec.

As a last resort, I replaced the control board with a brand new board, no change, but at least now I have a backup board!

I ran one test to turn off the propane at the tank while the fridge was on -- this produced the same error condition on the display panel, leading me to believe this might be something related to propane flow or something along those lines.

What else should I test or consider? Bad propane regulator somehow killing the propane under cold conditions? Misadjusted regulator? Bad eyebrow board?

Specs:
Model: DMR702
Product: 936002904
SKU: 9600010870

[GDS-3950BH]

sdtravis wrote:

AllegroD wrote:
Under warranty!

If only service appointments weren't months out!

Yep........and you have to drag the rig to a "Dometic Authorized" service center, typically an RV dealer, who has a bunch of incompetent hacks working and want you to leave the thing there for weeks if not months. All so you can get it back with more problems than it went in with.

[sdtravis]

SOLVED!

After replacing the Thermofuse, eyebrow board, main board and electrode/ignitor, the problem still wasn't fixed.

My attention turned to the valve solenoid next. The service manual states "The proper reading would be 49 ohms with tolerance range of ten
percent. Failure of the solenoid is very unlikely." Mine measured 44.6 consistently but given there's really not much left to try to replace I went ahead and replaced the entire valve assembly, inclusive of a new valve solenoid. Good news, problem solved, fridge stays on all night and I can now move on with my life with a functioning fridge. And now I have a box full of replacement parts I can use in the event the fridge starts acting up.

Hope this helps someone who has this problem with one of these DMR702 "Renaissance" gems in their rig.

[sdtravis]

AllegroD wrote:
Under warranty!

If only service appointments weren't months out!

[AllegroD]

Under warranty!

[sdtravis]

An update that adds to some of the mystery. I placed several cameras to get a better view of what happens when the fridge shuts down in the middle of the night and have a few interesting findings.

From the camera I put inside the exterior compartment, the fridge is running perfectly with plenty of flame then a loud click is heard (solenoid valve shutting) and the flame shuts down. There is NO attempt to relight the flame.

Two seconds later, the fridge starts displaying the error lights on the front panel.

If I close the valve on the propane or blow out the flame, the fridge automatically goes through 3 attempts at relight. In this instance the fridge is shutting itself down and not relighting which means its not likely to be an LP supply issue.

[sdtravis]

GDS-3950BH wrote:

Retired JSO wrote:
The Forest River site has a Dynamax Rep member that responds to questions about his products.

The Forest River site also has lots of posts/threads about that DMR-702 model fridge being garbage in a lot of cases. Its the first model that Dometic had the entire fridge outsourced to China and then slapped their name on it. They call it the Renaissance Series, perhaps the Junk series would be more appropriate? Dometic today is not the Dometic of 10 years ago. They took lessons from from LCI.

Its a very fair point, and I've read the same thing unfortunately.

The good news is that I can't reproduce the behavior whatsoever, so crossing fingers there may have been air in the line or something similar. Will post back if I find more info or come up with a solve.

Thanks everyone for your input on this.

[GDS-3950BH]

Retired JSO wrote:
The Forest River site has a Dynamax Rep member that responds to questions about his products.

The Forest River site also has lots of posts/threads about that DMR-702 model fridge being garbage in a lot of cases. Its the first model that Dometic had the entire fridge outsourced to China and then slapped their name on it. They call it the Renaissance Series, perhaps the Junk series would be more appropriate? Dometic today is not the Dometic of 10 years ago. They took lessons from from LCI.

[2oldman]

sdtravis wrote:

@2oldman and @2112: Agree, regulators fail but I wouldn't assume they'd fail so intermittently. I get full pressure on the stove at all times.

Refers consume much less propane, which requires much less gas flow, which *may* be an issue with the regulator. You might try the stove with just a trickle.

[Old-Biscuit]

sdtravis wrote:


@Old-Biscuit: Spark electrode is definitely suspect if in fact it returns a "hey a flame is present" to the control board. The error documentation on this leaves a lot to be desired, so based on my assumption those errors listed 1-3 aren't what I'm experiencing given both LP + temp flash (variably based on the setting, versus constant to the error). How would I know if that electrode is bad? A bad gap might also be a culprit too but would need to check the spec on that.

YES...spark electrode IS used for 'Flame Proving'
**Goggle -- Flame Rectification to see how

In the LINK i posted is the correct gap for spark electrode and position over burner
Pg 17

You can unplug it from transformer on the circuit board and check continuity

You can visually inspect the ceramic for any cracking...signal will go to ground vs returning to circuit board

You can physically check that the wire is not loose in the ceramic insulator
(High voltage can/does pass but milliamp current is easy to stop)

If flame has been incorrect ....fuel rich...then soot/carbon could be on electrode (clean it off with light sanding)


OTHER good info in that LINK also

[sdtravis]

Not a drive-by post!

Thanks all for your suggestions on this thread so far.

@2oldman and @2112: Agree, regulators fail but I wouldn't assume they'd fail so intermittently. I get full pressure on the stove at all times.

@newmanfulltimer: Moisture freezing not really possible in San Diego where we live pretty close to the ocean (41F at night). Though, a theory I was playing with did have something to do with the quality of the propane. This unit came from TX where they may have filled it with a mixture that the fridge isn't happy with for some reason. On your second comment, yes voltage and ground confirmed. Air obstruction is still a little unclear on how to test that, wouldn't having run all of the appliances including furnace, stove, etc just naturally purge that out?

@opnspaces: No yellow powder visible

@wa8yxm: Checked for the drain tube, in place where it should be. Good suggestion though.

@jkwilson: Also a good suggestion on a manometer. This is my third RV so just sort of looking at the pressure coming out of the stove, it seems like plenty, especially considering what's needed for the fridge. Furnace also works well which consumes at a much higher rate.

@Old-Biscuit: Spark electrode is definitely suspect if in fact it returns a "hey a flame is present" to the control board. The error documentation on this leaves a lot to be desired, so based on my assumption those errors listed 1-3 aren't what I'm experiencing given both LP + temp flash (variably based on the setting, versus constant to the error). How would I know if that electrode is bad? A bad gap might also be a culprit too but would need to check the spec on that.

@Retired JSO: Correct, Dynamax is very responsive on their issues but given this is a Dometic issue vs the coach at this point they're deferring that back to the refer mfg.

Love the good ideas here. Will be taking the Isata out for the weekend to test it out and hopefully will have some more data to share.

[MFL]

2oldman wrote:
I am really hoping this isn't a drive-by post.

A recent consensus, seems to require a minimum of 3 days for OP to return, and a bit more due to a Holiday between.

Jerry

[2oldman]

I am really hoping this isn't a drive-by post.

[Retired_JSO]

The Forest River site has a Dynamax Rep member that responds to questions about his products.

[newman_fulltime]

Old-Biscuit wrote:
The error code is always the same -- two blinking lights,

One is LP
*Gas ignition failed. The gas flame has not been ignited after 45 seconds.

Other -- Temp Setting 1-3
1) *Disconnected gas valve or hardware fault in the gas operation system. (Check the Wire Connections ON Gas Valve and ground connection J1 Position on Circuit Board)
(Check the Spark Electrode wire connection/ceramic insulator for cracks and electrode position/gap over burner)
2) *A faulty temperature sensor device or a fault in the associated electronic circuitry has occurred. (that would be Thermistor connection or the circuit --- J3 Position on Circuit Board)
3) *DC voltage is out of range (drops below/exceeds the limit values approx. 8-18V DC). Very Wide Range on DC Voltage


Suspect #1
Spark Electrode is DUAL Function....provides High Voltage Spark for Ignition AND Return path for Flam Proving Signal (Current generated by flame ionization ---circuit board senses this current/keeps DC on gas valve. No signal/DC to gas valve dropped/error code triggered
Current is only a few milliamps so doesn't take much to stop it/go to ground

Installation & Operating Manual

Lp light blinking is no gas flow through the valve .
Second light blinking is gas valve misfunction or hardware misfunction .
Check for air or obstruction in line check ground and voltage at gas valve