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Old 05-23-2020, 05:16 PM   #1
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THOR #11527
AC current leaks into DC circuit Refrigerator problem

I've had a problem with the Dometic 2652 refrigerator since I first got my RV new in Feb 2018. The fridge stops working and the "check" light goes on randomly -- maybe 1 - 4 times a day. Doesn't matter whether or not I'm on shore power. I took it to the dealer, they kept it for a week, "couldn't replicate the problem," and charged me $200 for the diagnostic. The dealer is 100 miles from me, so I really don't want to bother with that again.
So for the past couple of years, we'd all just keep an eye on the fridge and when the check light goes on we just turn the fridge off then back on again and it's good for a while.
I finally got some time to look into this, so I got the diagnostic manual. In section 4, DC Voltage Requirements, it says "the Dometic control system will only tolerate up to 6 AC volts on the DC line." I tested the DC line at the refrigerator's main DC terminal block, and it reads 28v AC. I got the same ~28VAC reading from the other DC items I checked, and I also got the AC voltage in the wiring panel between the main 12V post and the ground bar.
What would you guys do to fix this? The fridge is probably fine since the DC circuit is way outside the specs.
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Old 05-24-2020, 03:10 AM   #2
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Quote:
Originally Posted by Snarltoof View Post
I've had a problem with the Dometic 2652 refrigerator since I first got my RV new in Feb 2018. The fridge stops working and the "check" light goes on randomly -- maybe 1 - 4 times a day. Doesn't matter whether or not I'm on shore power. I took it to the dealer, they kept it for a week, "couldn't replicate the problem," and charged me $200 for the diagnostic. The dealer is 100 miles from me, so I really don't want to bother with that again.
So for the past couple of years, we'd all just keep an eye on the fridge and when the check light goes on we just turn the fridge off then back on again and it's good for a while.
I finally got some time to look into this, so I got the diagnostic manual. In section 4, DC Voltage Requirements, it says "the Dometic control system will only tolerate up to 6 AC volts on the DC line." I tested the DC line at the refrigerator's main DC terminal block, and it reads 28v AC. I got the same ~28VAC reading from the other DC items I checked, and I also got the AC voltage in the wiring panel between the main 12V post and the ground bar.
What would you guys do to fix this? The fridge is probably fine since the DC circuit is way outside the specs.
"Doesn't matter whether or not I'm on shore power."
When not on shore power are you running the generator?
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Old 05-24-2020, 02:30 PM   #3
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THOR #11527
For the AC Ripple issue -- ugh. I'm not sure about that 28V AC because I'm getting 3 different readings from 3 different instruments, so it might not be the issue.

However, the refrigerator shut-off issue happens whether or not the generator is running. I'm usually dry camping, so I run the fridge off of propane most of the time.
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Old 05-24-2020, 02:38 PM   #4
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The real question is:

Do you have the fridge problem with no AC applied to the coach (generator or SP)?

28 VAC on a 12 VDC line is grossly excessive. Is your multimeter on "Auto"? Could that be 28 millivolts AC?

You may be chasing the wrong symptom.
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Old 05-24-2020, 06:35 PM   #5
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Originally Posted by 16ACE27 View Post
The real question is:

Do you have the fridge problem with no AC applied to the coach (generator or SP)?

28 VAC on a 12 VDC line is grossly excessive. Is your multimeter on "Auto"? Could that be 28 millivolts AC?

You may be chasing the wrong symptom.
Yes, I was chasing the wrong symptom! The multimeter on "auto" messed up the readings. There's probably no AC current problem.

The problem is that the fridge cuts off and shows the check light no matter what power is applied to it. So -- if the coach is on AC through shore or generator, the problem happens. If the coach isn't on AC at all, the problem still happens. It's a 2 way fridge so it should work on propane or AC.

The fridge runs great until it just lights the "check" light then it's completely off, no inside light or anything.
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Old 05-24-2020, 07:15 PM   #6
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I did a search for Dometic 2652 and it gave me the DM2652, same one I suspect?
Then the Dometic website has the operating manual for the DM2652 and in there it states:
"If the CHECK indicator lamp is illuminated the controls
have failed to ignite the burner in the GAS mode.
To re-
start an ignition attempt with the CHECK lamp illuminated
(or to turn off the CHECK lamp), press the ON/OFF button
OFF and back ON again. The control system activates
the ignition system and makes three attempts to light the
burner for a period of approximately 45 seconds at two
minutes interval. Should 120 VAC become available while
the CHECK indicator lamp is on, the CHECK lamp will not
turn off until the ON/OFF button is pressed OFF and then
ON again."
So does the AC part work? I read into it that the "check" light is only for the gas operation.


Edit:
Found the diagnostic manual for the RM2652 and it states the same:
"If the CHECK indicator
lamp (B auto or E adjustable thermostat) illuminates, the
control has failed to ignite the burner on GAS."
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Old 05-24-2020, 07:39 PM   #7
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Originally Posted by OldWEB View Post
I did a search for Dometic 2652 and it gave me the DM2652, same one I suspect?
Then the Dometic website has the operating manual for the DM2652 and in there it states:
"If the CHECK indicator lamp is illuminated the controls
have failed to ignite the burner in the GAS mode.
To re-
start an ignition attempt with the CHECK lamp illuminated
(or to turn off the CHECK lamp), press the ON/OFF button
OFF and back ON again. The control system activates
the ignition system and makes three attempts to light the
burner for a period of approximately 45 seconds at two
minutes interval. Should 120 VAC become available while
the CHECK indicator lamp is on, the CHECK lamp will not
turn off until the ON/OFF button is pressed OFF and then
ON again."
So does the AC part work? I read into it that the "check" light is only for the gas operation.
When working correctly that is what the "check" light tells you. You should never see the "check" light while operating with 120 VAC present.

So, either the OP randomly and pretty consistently looses 120 VAC to the fridge when operation on SP or the Generator AND he also has a consistent gas lighting problem the I would wager he has a bad control board, which is a pretty common problem anyway.

I would spend the money on a Dinosaur control board and see if that doesn't fix it.

This should be the one for the OP's fridge:
https://www.dinosaurelectronics.com/DE_3850712.html

Verify it per their chart. You can get it at Amazon for about $125 with free shipping.
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Old 05-24-2020, 07:40 PM   #8
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Thanks!
Yes, that's the same fridge. That's a good find. The problem does happen when it's on AC. The 2 modes of operation are "automatic" and "propane." So I usually leave it on "automatic."

Is it possible that it's periodically trying to ignite the burner even though there is 120v available?

And is it possible that the igniter only fails sometimes?
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Old 05-24-2020, 08:01 PM   #9
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Originally Posted by Snarltoof View Post
Thanks!
Yes, that's the same fridge. That's a good find. The problem does happen when it's on AC. The 2 modes of operation are "automatic" and "propane." So I usually leave it on "automatic."

Is it possible that it's periodically trying to ignite the burner even though there is 120v available?

And is it possible that the igniter only fails sometimes?
Possible? Yes - but that would be a control board failure.

Possible? Yes, but it would have to be a frequent failure for it to occur while normally running on gas as well as when the control board incorrectly calls for a gas ignition when you have 120 VAC available.

As I said, I'd go with the most likely cause historically and replace the control board. If you still have ignition problems after that you can troubleshoot that single issue.
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Old 05-25-2020, 12:04 AM   #10
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THOR #11527
Thanks for all that info! I'll try replacing that board. Sounds like a good idea.
How do I find the dometic part number of my current board? The only number that looks like a part number I can see on the board is 50-143401-C.
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Old 05-25-2020, 12:13 AM   #11
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Originally Posted by Snarltoof View Post
Thanks for all that info! I'll try replacing that board. Sounds like a good idea.
How do I find the dometic part number of my current board? The only number that looks like a part number I can see on the board is 50-143401-C.
Look at this page under "Replacement by model number" and then verify the serial number of your fridge and which row it falls into:



https://www.dinosaurelectronics.com/Dom_Chart.htm
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Old 05-25-2020, 12:34 AM   #12
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ops duplicate link
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Old 06-01-2020, 04:19 PM   #13
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I just wanted to give you an update -- I didn't order the control board yet, however the refrigerator hasn't failed in about a week. It used to do it at least once a day for the 2 years that I've had it, so I think it's good.

The DC power wires weren't very tight in the power block when I disconnected them to try to troubleshoot, so I tightened them when I put the wires back in. That was probably the problem -- loose wires on installation.
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Old 06-01-2020, 07:58 PM   #14
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Well, good show!
Doing a tightness check on the wiring should be done or at least a visual inspection to see if overheating is occurring. Even when you unplug a cord, is the end(s) warmer than ambient or discoloured? If it is, those are signs of overloading, corrosion or even loose connections and should be investigated. In your case, it may have caused unusual operation...
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