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Topic: Short in Refrigerator Blowing 20a Fuse in Fuse Panel (Read 232 times) previous topic - next topic
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Short in Refrigerator Blowing 20a Fuse in Fuse Panel
My fridge, a Dometic RM3662, in a 2003 23.5 Front Dinette, is blowing the 20 Amp fuse in the converter fuse panel. When trying to replace it, there are sparks and the new fuse is blown. The eyebrow has no lights and the fridge is off. It does not work on AC either.

The fridge was working fine before the 21 mile road into Chaco Canyon but was not working at the end of it so I can only assume that the vibrations shook something loose or created a short. I called the factory and they said it was highly unlikely that the cable from the converter to the fridge was shorted due to how it was installed in a tunnel and protected under the floor.

So it seems to be either the fridge control board or the fridge itself. I'm going to try to have a tech look at it in Flagstaff next week, but would appreciate any ideas.

Bob

2003 23.5' Front Dinette
Re: Fridge blowing fuse
Reply #1 –
From the symptoms you describe, you have a dead short. If it were me, I'd open up the outside access door and look at the connections to the control board. Those are just compression-type screw terminals, and it's possible a wire has come loose. The 12 V and ground wires that power the controller board go into a white terminal block at the right of the black control board housing. In the attached photo, they are the pink and white wires. (This is a 3762 in my Airstream, but your 3662 is probably going to look very similar.) They would be my first suspect. If the positive wire should slip out of its screw  terminal, you'd have exactly the symptoms you describe.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Fridge blowing fuse
Reply #2 –
Thanks Andy,

The pink 12v POS is secure in the fridge compartment.

I wanted to eliminate the motorhome wiring as the place for a short so I ran a cable from the converter fridge 12v POS under the fuse directly to the 12v POS connector on the outside panel. Fuse still shorted. This leads me to believe the Motorhome under floor wiring has no short.

I then hooked it all back normally and undid the 12v POS from the outside compartment, replaced the fuse with no sparks, and then reattached the 12v POS at the compartment. The fuse blew immediately.

This all leads me to think that the short is either in the control board or the fridge itself. So I guess I buy a new control board and see if that fixes it, or replace the entire fridge. It's 14 years old so probably not a bad idea.

 
2003 23.5' Front Dinette
Re: Fridge blowing fuse
Reply #3 –
OK, got the fridge fixed. It turned out that the thermal cutout wire was slightly worn on the black rubber wrap. It attaches to the flue under a metal clamp. The cut was about 1/4", just enough to short out on the metal clamp. A new short piece of shrink wrap fixed the problem.  Actually it was working as intended as the short there generated heat which then activated the cutout and shut the fridge down.

For anyone else with a similar issue, the red wire from the 12V POS connector goes back to the flue pipe and doubles back on itself. There is a black wrap over the doubling. The cutout is under this black wrap. It is there in case the gas flame gets too high or catches fire, the cutout on sensing high heat, shuts the fridge off.

The washboard road into Chaco Canyon bounced the coach enough so the metal clamp wore or cut the wrap when they meet.

If ever in Flagstaff, high praise for Aspen RV Mobile service.
2003 23.5' Front Dinette
 
Re: Fridge blowing fuse
Reply #4 –
Thanks for the update, Bob. Glad it was a simple fix!
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"