dometic 3-way swtich

[RT-NY]

Has anyone replace/fixed the manual switch on the older dometic 3-way fridges? Mine doesn't switch to 12 volts (after a time of intermittent failures) even though there is 12 volts at the terminals. It looks to be a pretty simple design so perhaps the contacts just need cleaning up, but either way requires taking it out, which looks to require disconnecting and removing some of the propane fittings which I don't have time for right now. I am thinking of putting in a temporary bypass switch though there are risks in that if I forget to switch it off! Any suggestions?

[GallenH]

Not so far. My 2310 switch is getting "sluggish." I have to replace the thermostat and when I do that I'm planning to use some electrical contact cleaner. I think there's a place in Canada where you can buy a whole new switch. Ok. In looking at the 2310 wiring diagram it's pretty clear that you could take the incoming 12v and connect it to the leads for the 12v heating element with a switch as you suggest. I suppose if the electrical was shot in the factory switch you could get a DPDTw/center off switch and control both 12v and 120v from there; reserving the center off for gas. I believe you'd still need the original switch for its gas position.

[RT-NY]

Originally Posted by GallenH

If the electrical was shot in the factory switch you could get a DPDTw/center off switch and control both 12v and 120v from there; reserving the center off for gas. I believe you'd still need the original switch for its gas position.

Right. You would need the control knob on the front of the fridge for the gas, but I think that the gas is not actually controlled by the switch itself - the rod on the knob basically passes through to a simple gas valve, which is why it needs to be removed to get at the switch.

It is probably also a good idea to use a DPDT switch, as you suggest, to avoid the risk of accidentally leaving two heat sources running at the same time which might causes overheating problems -- also some kind of reminder at the propane igniter button!

The surprising (and, for me, advantageous) thing about the RM2310 is that there are no electronics in it at all - even the thermostat is mechanical. I believe that the 12v/120v is only used for the heating elements.

[Bud]

Originally Posted by RT-NY

Has anyone replace/fixed the manual switch on the older dometic 3-way fridges? Mine doesn't switch to 12 volts (after a time of intermittent failures) even though there is 12 volts at the terminals. It looks to be a pretty simple design so perhaps the contacts just need cleaning up, but either way requires taking it out, which looks to require disconnecting and removing some of the propane fittings which I don't have time for right now. I am thinking of putting in a temporary bypass switch though there are risks in that if I forget to switch it off! Any suggestions?

Or run on ac or propane and ignore dc which does Not make as much heat.

[tlillard23]

I run mine on AC from the inverter. rigged a cord from the tv cabinet to the fridge.The12 option is the least efficient, least cold option.

or as you said, try spraying the switch with deox or other contact cleaner?

[RT-NY]

Originally Posted by tlillard23

I run mine on AC from the inverter. rigged a cord from the tv cabinet to the fridge.The12 option is the least efficient, least cold option.

or as you said, try spraying the switch with deox or other contact cleaner?

I can't see any easy way of running a cord from the TV cabinet to the back of the fridge in my Dodge RT. I agree that cleaning up the switch would probably work, but I can't get to it without taking things apart more than I have time for right now. The 12 volt is less cold, but that might be an advantage because the thermostat looks to be faulty so the 120 volt gets too cold! The 12 volt doesn't use the thermostat.

Anyway, as a temporary fix, I added a short length of 14awg wire in the back of the fridge to bypass the swtich, added a SPST switch inline with the fuse inside the van so I can shut it off, and put a piece of tape on the control knob as a reminder not to turn it to 120 volts! I am running 12 volts even when on shore power and can use it also when driving or use propane as needed. So far so good (though the fan on the converter/charger goes on more often, which is a bit annoying).

[GallenH]

Sounds good. I'm attaching a pic of the diagram for my 2310. I found it a bit hard to read but it does show the various junction boxes for the wiring. Interestingly, to the right of the solid vertical line it details the thermostat (B) involvement when in both 120v and 12v modes. In 12v mode the negative incoming 12v line goes directly to one wire of the 12v element. The 12v+ goes to one pole of the switch which sends it to the thermostat. The return from the thermostat goes back through the other pole of the 12v switch and on to the other wire of the 12v element. So the 12v mode actually does use the thermostat. However connecting the 12v incoming directly to the heating element (with an intervening SPST switch) essentially does the same thing as running it through the thermostat with the thermostat set on max....which you need to do anyways to get the most possible cooling. Sorry for the wordiness.



Wiring.png

[RT-NY]

Originally Posted by GallenH

So the 12v mode actually does use the thermostat. However connecting the 12v incoming directly to the heating element (with an intervening SPST switch) essentially does the same thing as running it through the thermostat with the thermostat set on max....which you need to do anyways to get the most possible cooling. Attachment 13988

Thanks for that! I see that I was mistaken -- I am bypassing both the switch and the thermostat, and connecting directly to the 12v heater. I suppose that on a cold day it might still get too cold in the fridge running non-stop, but so far it seems to run at an acceptable temperature.