Frigerator 120V Not Working

[Patrick M.]

The 120v heater on our 3-way Dometic RM2193 appears to have quit working after a horrible drive on 4 miles of washboard road. (Such roads now permanently on the banned list.) The outlet that the refrig is plugged into has power, but no heating, and thus cooling, is occuring. Propane and 12V cooling is working fine.

So I assume it could be either the heating coil or the thermostat, but before I start poking around I wonder if anyone has any advice?

Thanks

Pat

[wayne s]

The 120v heater on our 3-way Dometic RM2193 appears to have quit working after a horrible drive on 4 miles of washboard road. (Such roads now permanently on the banned list.) The outlet that the refrig is plugged into has power, but no heating, and thus cooling, is occuring. Propane and 12V cooling is working fine.

So I assume it could be either the heating coil or the thermostat, but before I start poking around I wonder if anyone has any advice?

Thanks

Pat

I would check the 110 heating element, It is easy to replace. Wayne

[Morgan]

Pat,

The more likely problem is that a connection vibrated loose. You should verify each connection in the AC circuit.


If you have a multimeter, disconnect the power and check the resistance across the AC heating element. If that's open, the heating element is bad.

With the thermostat set to maximum, check the resistance across the thermostat (black to white). It should read zero ohms. If not, the thermostat is bad.

If the thermostat is not switching power, it could be that the capillary tube is broken. The capillary is an integral part of the thermostat and is a very skinny tube leading in to the back of the refrigerator to a capillary bulb which senses temperature. If that tube is broken, the thermostat will think it is very cold in the refrigerator.

If you replace the thermostat, be very careful to not kink the capillary tube on the new one.

This schematic will help your troubleshooting:

[Donna D.]

Patrick, if you need it, here's the link to the Dometic RM 2193 Manual
from the Document Center: Dometic RM 2193

[Patrick M.]

It was one side of the 120 volt double-pole switch! How bizarre and unusual is that!
Removing the control panel to get to the wires for testing was a little tricky, what with short wires attached to this and that. I connected the wires together with the thermostat and it's cooling down nicely. By the way, I noticed in the Dometic parts manual that the watts for the 12v heater and the 120v heater are the same at 115.

PPL Motorhomes parts wants $28 for this plastic switch that might cost $0.10 to buy from China, so I'm on a search for an alternative. Mouser Electronics, where I got the relay for my A/C thermostat project (which failed on the trip and subject of a future post), has similar switches for $2-$4, for example.

Thanks to all for the help. One punch list item almost down, several more to go!

[Morgan]

You might want to call Scamp and get a price from them - probably way cheaper than PPL. They may have to order it from Dometic.

I just ordered Dometic parts from Casita. One little brass jam nut was $9.00.

[Patrick M.]

I decided to pry open the switch and take a look. The contacts were reasonably clean but one had a slight dark spot. I cleaned all off, put it back together, and waalaa, it is working again. Calling Scamp was next on the list should that have failed.

Another alternative to buying a new switch would be to just use the good side of it, connecting the wires previously on the other side together. Off hand I don't see a big concern with doing that. Another alternative to the $28 solution would be to wire the lines together and replace the 120v duplex plug the refig is plugged into with one that has a single plug with a switch.

Anyway, all done and now testing it on and off for the next few days.

Pat

[Morgan]

You did good, Pat.

I apologize for my tutorial type post, but I had no idea what your level of competence was. You apparently know what you're doing.

One caution (you probably know this): should you use just one side of the switch in the future, switch the hot line rather than neutral. Otherwise all the circuitry out to the heater and back is at a 120 VAC potential.

Morgan

[Patrick M.]

Morgan, no need to apologize as your information will no doubt be valuable to a future reader. And your tip on the capillary tube was one I hadn't considered, and as I had to pull the thermostat partly out to get to the wires, I was thus prepared to be careful of the capillary tube.

As it was, the connections were all very tight in my 2-year old unit.

And I think they make the hot side of A/C lines black to remind you of what color you hands or house may become if you fail to switch it, rather than the neutral side!