Dometic DM2652 not cooling on AC power

[bfourman]

Dometic DM2652 2 way fridge, made in 08/09. Last season it worked perfectly. At the start of this season it decided to only work on gas. I have gone through all of the Dometic troubleshooting and finally determined that the board had to be bad. I just replaced the board with a Dinosaur unit and the problem remains.

On first start with the Dinosaur board, it ran on AC for about 30 seconds then started firing the ignitor for the gas. I unplugged the fridge from the camper and plugged it directly into the garage outlet, same story so I know the camper outlet is good.

The AC heater element tests at 41.9 ohm, within range of the specified 44 ohm from the manual. All fuses are good
It runs great on gas, but obviously I would like to run it on shore power while camping.

What am I missing here?

[bfourman]

Update - eyebrow board was the problem. Used the camper this past weekend and the fridge performed as normal.

[SidecarFlip]

If you are someone else replaces the 120 VAC Mullion Heater, that would be a good time to pull the flue baffle and clean it, blow out the burned and run a bottle brush down the flue to remove and carbon buildup.

[mr__ed]

SidecarFlip wrote:

bfourman wrote:
Called the local RV shop and talked to the tech. He is leaning towards the eyebrow being bad since I'm not getting voltage to J7/J8. He has a tester in the shop, so now I get to decide if I'm going to drag the camper 20 miles for a diagnostic or just order a eyebrow and cross my fingers...

Tell him you have cold beers in the house fridge and ask him to make a house call.......:W

Be sure to serve the beers AFTER the job is finished! :B

[SidecarFlip]

bfourman wrote:
Called the local RV shop and talked to the tech. He is leaning towards the eyebrow being bad since I'm not getting voltage to J7/J8. He has a tester in the shop, so now I get to decide if I'm going to drag the camper 20 miles for a diagnostic or just order a eyebrow and cross my fingers...

Tell him you have cold beers in the house fridge and ask him to make a house call.......:W

[mr__ed]

Just testing for 120 volts at the heater wires isn't enough. The heater could be burnt out, not drawing any current, which wouldn't show up in a simple voltage check. The sure way to check that it's drawing current is by using an ammeter, or simply putting hand or finger near the heater to feel for heat. Or use an infrared thermometer.

[bfourman]

Called the local RV shop and talked to the tech. He is leaning towards the eyebrow being bad since I'm not getting voltage to J7/J8. He has a tester in the shop, so now I get to decide if I'm going to drag the camper 20 miles for a diagnostic or just order a eyebrow and cross my fingers...

[bfourman]

Old-Biscuit wrote:
It didn't run on AC..that 30 seconds is time it took to check for AC power and then swap to gas cause NO AC available


Did you verify that the 120V AC outlet fridge power cord plugs into actually has AC Voltage>......plug a lamp in it, TEST it with voltmeter? Yes

Outlet Good....
Verify AC Voltage on board (J5/Hot J6/Neutral) Yes
Then need to check if AC Fuse ON circuit board has blown? Fuse good
(did you check that on 'other' circuit board before replacing?) Yes

Fuse blown......AC element bad

Fuse good.....check for AC voltage on J7/J8....leads to element (with fridge in AUTO and thermostat setting at MAX so cooling is called for)

No voltage on J7 & J8, checked as my assistant ran the fridge button.

[bfourman]

Well I have to eat a bit of humble pie. In my haste to get things going I neglected to make sure it wasn't forced to gas operation on the eyebrow. I guess having 4 kids running around will do that...

Still no operation on AC though.

[Old-Biscuit]

bfourman wrote:
Dometic DM2652 2 way fridge, made in 08/09. Last season it worked perfectly. At the start of this season it decided to only work on gas. I have gone through all of the Dometic troubleshooting and finally determined that the board had to be bad. I just replaced the board with a Dinosaur unit and the problem remains.

On first start with the Dinosaur board, it ran on AC for about 30 seconds then started firing the ignitor for the gas. I unplugged the fridge from the camper and plugged it directly into the garage outlet, same story so I know the camper outlet is good.

The AC heater element tests at 41.9 ohm, within range of the specified 44 ohm from the manual. All fuses are good
It runs great on gas, but obviously I would like to run it on shore power while camping.

What am I missing here?

It didn't run on AC..that 30 seconds is time it took to check for AC power and then swap to gas cause NO AC available


Did you verify that the 120V AC outlet fridge power cord plugs into actually has AC Voltage>......plug a lamp in it, TEST it with voltmeter?

Outlet Good....
Verify AC Voltage on board (J5/Hot J6/Neutral)
Then need to check if AC Fuse ON circuit board has blown?
(did you check that on 'other' circuit board before replacing?)

Fuse blown......AC element bad

Fuse good.....check for AC voltage on J7/J8....leads to element (with fridge in AUTO and thermostat setting at MAX so cooling is called for)

[Joe417]

If you are electrically inclined, You can connect 120V directly to the heater element. If the element is good it will be cold in the morning, 12 - 24 hours.
This bypasses the thermostat/controls.

I keep a short double ended bypass cord in the camper just in case I have control or gas problems while traveling.

Be safe, it is 120V.

On our Norcolds, the controls allow me to choose AC, DC, Gas, or Auto.
I have accidently put it on Gas when I wanted it on Auto. For me, the gas was low so it lit, I shut the door and went in the house. Next morning it was still warm.

I'm sure I'm the only one that has ever done that.

[ScottG]

Check for voltage at the heater wires while it's running. It rare but you could have an active-open in the element. That is, it measures fine until you apply power and it "opens".
So if there's 120V to the wires of the element, replace it.
Otherwise I would check all the safety sensor crud they put on them to stop fridges from burning us down.

[Kayteg1]

Can you test 120V on heater wires?
I doubt you will feel a heat on the tube?