Fridge not working on AC

[Parker Buckley]

The Dometic three-way fridge in our new-to-us 2005 Casita doesn't work on 120V. It works fine on propane and on 12V DC. There is power at the outlet. I plugged it in through a Kill-A-Watt meter and determined that it's not drawing any current when switched on.

Is there a common electric heating element for 12V and 120V? If so, then that's not the problem. But I don't think one heating element could work at both 12V DC and 120V AC, so there are probably two. I read the manual (!) and learned that the thermostat is only used on 120V. So I'm going to check that the on/off switch works, and that the thermostat switches on. And I assume I'll be able to check for continuity of the 120V heating element. Anything else come to mind before I start digging into this?

Thanks,
Parker

[Bill K]

Just be sure you UNPLUG the 120v AC before checking for continuity.

Bill K

The Dometic three-way fridge in our new-to-us 2005 Casita doesn't work on 120V. It works fine on propane and on 12V DC. There is power at the outlet. I plugged it in through a Kill-A-Watt meter and determined that it's not drawing any current when switched on.

Is there a common electric heating element for 12V and 120V? If so, then that's not the problem. But I don't think one heating element could work at both 12V DC and 120V AC, so there are probably two. I read the manual (!) and learned that the thermostat is only used on 120V. So I'm going to check that the on/off switch works, and that the thermostat switches on. And I assume I'll be able to check for continuity of the 120V heating element. Anything else come to mind before I start digging into this?

Thanks,
Parker

[Al V]

is there power at the plug?

[Parker Buckley]

The Dometic three-way fridge in our new-to-us 2005 Casita doesn't work on 120V. It works fine on propane and on 12V DC. There is power at the outlet. I plugged it in through a Kill-A-Watt meter and determined that it's not drawing any current when switched on.

Well, it appears that the 120V heating element is open. The power switch and thermostat show continuity, but the heating element does not. So, has anyone replaced a heating element, or is this something that needs to go to an RV shop? I haven't tried opening up the sheet metal around the boiler tube yet, but it appears that's a fairly common operation for cleaning.

Parker

[Harry Young]

Parker,

You should be able to do this, use a heat transfer paste when you reinstall the element...The stamped number on the element is often the watts of the unit. Try to get as much of it in contact with the tube/holder it fits in, if there is not enough contact they over heat and burn out prematurely.

Happy camping, Safe trails.

Harry

Well, it appears that the 120V heating element is open. The power switch and thermostat show continuity, but the heating element does not. So, has anyone replaced a heating element, or is this something that needs to go to an RV shop? I haven't tried opening up the sheet metal around the boiler tube yet, but it appears that's a fairly common operation for cleaning.

Parker

[Parker Buckley]

Parker,

You should be able to do this, use a heat transfer paste when you reinstall the element...The stamped number on the element is often the watts of the unit. Try to get as much of it in contact with the tube/holder it fits in, if there is not enough contact they over heat and burn out prematurely.

Happy camping, Safe trails.

Harry

Harry,

Thanks for replying....I thought I might end up replying to myself again! I've pulled the element and have a new one on the way. It's a roughly 3/8" diameter tube with a 90 degree bend, with power and ground wires coming out of it. The business end is welded closed. It goes in vertically and fits loosely through a small bulkhead around the propane burner area, and doesn't fit into anything tightly enough to use heat transfer grease. When I read your post, I thought maybe I was going to be replacing just the heating element down in this tube, but it all seems to be potted in with high temp RTV. I guess I'll know for sure when I get the new one.

What I'm really concerned about now is how to get that sheet metal wrap and insulation back around the flu. Getting it opened up to pull the element was not pretty. As you probably know, it has a vertical lap seam along its length. It's one thing to install on the production line, and quite another to do it working through a hole in the side of the Casita. I may end up pulling it out entirely to straighten the seams before trying to re-install. That doesn't look like fun either. Any hints would be most appreciated.

Parker

[DonDeutsch]

Hi Parker,
I have been following the thread because I have wondered about how these work. (Mine is still OK). If you could post pictures or diagrams as you do the repair, it would be interesting to me and perhaps others too.

[Parker Buckley]

Hi Parker,
I have been following the thread because I have wondered about how these work. (Mine is still OK). If you could post pictures or diagrams as you do the repair, it would be interesting to me and perhaps others too.

Don,

When the new heating element arrives, I'll take some photos. I would like to have had a schematic to work from, but I think I have it pretty well figured out. This whole thing would be WAY easier with the fridge out on a bench. My only concern at this point is getting the galvanized cover back around the flu. They used a simple lap joint bent into the sheet metal, kinda like a stove pipe, but it's very difficult to squeeze the joint together enough to open the thing up. I hope I can get it zipped back up okay. This would have been a great place for a couple of SS hose clamps (and just an overlap of the sheet metal and no seem) as a courtesy to anyone needing to work on it.

Basically, the flu is situated over the propane burner, logically enough, and both the 12V and 120V heating elements come in from the side of the galvanized cover and bend down parallel with the flu, with their tips down in the same general area as the propane burner. Electrically, I could almost sketch out a schematic at this point, but it would be easy to miss something in the tangle of wires. Maybe someone could post one for us at some point.

Parker

[Bill K]

Try this pdf file and go to the last page.
It may not be the same as yours but it may help.

Bill K

[PDF] <h3 class="r">1-04-05 RM2354 Installation and Operating Instructions<a href="java script:void(0)" id="LXPLSS_1979792194U1">

[Parker Buckley]

Try this pdf file and go to the last page.
It may not be the same as yours but it may help.

Bill K

[PDF] <h3 class="r">1-04-05 RM2354 Installation and Operating Instructions<a href="java script:void(0)" id="LXPLSS_1979792194U1">

Bill,

That's what I had in mind, but it's for a much fancier unit. Ours is the RM2193, same as in the 13' Scamps. Also, it looks like your example uses circuit boards, while ours uses chassis mounted components and spade lugs for all the connections. It's hard to tell where things go on the boards after arriving at a connection point; at least at first look. I may hand-draw a schematic from ours before I'm finished. One thing I found interesting on ours is that they use a double pole on-off switch for the 120V circuit, swithing both legs. That's probably good safety insurance with the likelihood of dodgy grounding at campsites.

Thanks for posting!
Parker

[Angelo F.]

Ouch. Yeah, after looking at that heat shield......

I would use the clamps to get it cranked down to where you need it to, and if you're unable to get the seam back together, drill some holes along the length of it and pop in half dozen rivets or so. Finish sealing it up with metal tape.

[Angelo F.]

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