Dometic RM36 3-way fridge fuse

[Richard Vining]

Hi there, 

I was hoping someone could help me out, with the fridge I have in my 1977 dodge sportsman based c-class. 

It has a Dometic RM36 fridge in it, and the good news is it runs great on propane, and I've got it working pretty well off of the 110 as well, but there is a fuse missing from the 12volt circuit, and I cannot for the life of me figure out what kind of fuse it is, or even the amperage it is supposed to be. 

I feel like it might be some kind of weird old fuse that isn't common anymore, if so I might change the fuse holder out, but I still need to figure out the amperage it is supposed to be.

Cheers,

Richard

[Jimco_W001]

Richard,please check out the RV Manuals page.The RM fridge is listed there.If you need any more help please let me know.

[Richard Vining]

The manual just said to fuse with an appropriate fuse, but it said that the maximum draw for that model is 10amps. I think I will just try rewiring the fridge with a new fuse holder and a 10amp fuse and see if that works. 

Thanks for the quick reply, I appreciate it!

[Jimco_W001]

Richard,the normal DC fuse rule is use a fuse that is 2x's the amount of current that the circuit uses.

[Richard Vining]

Thanks Jimco, 

That will probably save me a few fuses!

[Leah Fletcher]

Where is this manual? I can't find it, thanks

[John Demarrais]

Fuse size is determined by two factors.  #1 it must be big enough to run the load.   #2 is must be small enough to blow before the wire melts so that is determined by the gauge of the wire used in the circuit.  Your refrigerator draws 9-10 amps @ 12 volts.  So the minimum size should be a 15 amp fuse.   If the wire size is 14 gauge or larger - that will be fine.

14 gauge copper wire needs a 15 amp fuse or smaller to protect it, 12 gauge needs a 20 amp or smaller fuse,  10 gauge needs a 30 amp or smaller, etc.  You do NOT need a fuse twice the amp rating for your refrigerator since it has no motor.  Your refrigerator uses an electric resistance heating element that draws a steady 9-10 amps.  NO surge when it first comes on.   If you had a compressor-driven appliance - it might draw twice its amp rating every time the motor first started.

[Terry H]

[Leah Fletcher]

Hmmm Nothing showed up in your reply. 

[Terry H]

My apology. Don't know what happened. I'll try again...........

[Leah Fletcher]

Thank you so much. Just got a Boler with one of these in it and it needs a little work. This will help a ton. Thanks again! I am assuming RM 36 F versus a RM 36 C really is just a different model of the same series. The pictures look very similar to ours.

[david craft]

The fridge is probably a 3 way and the 3rd option is 12v and you're not using it. The service manual shows 9 amp draw on the 12v side of the element. A 15 amp fuse should be fine. You should only use this option while traveling.

[david craft]

I use to believe that 12v operation was not worth it. They never cooled well on 12v and the drain while operation reduced house battery charge potential. But, fires have occurred while traveling due to cooling core failure and hydrogen gas igniting. It seems road vibration prompts core failure while traveling and that could be a good reason to use the 12v option, especially on older units.