RVNOOBS Posted July 23, 2015 Author Share Posted July 23, 2015 OK, looked at the 12V side of the fridge this morning. There is a fusable link in a 12V wire and I can't find what size, amperage, etc. belongs in there. I connected the 2 ends of the wire and the heat tubes heated up (good thing) but the wire got way hot after just 5 minutes. Thoughts? Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 24, 2015 Share Posted July 24, 2015 They draw a lot of current on 12 volts so warm maybe Ok hot I guess is a matter of opinion as long as there is fuse protection you should be fine. Years ago I tested mine and the 12 volt draw was around 12.5 amps I never run mine on 12 volts and only on 120 the day before I go camping it uses so little gas even if I'm at a camp ground I just leave it on gas. Quote Link to comment Share on other sites More sharing options...
WME Posted July 24, 2015 Share Posted July 24, 2015 A Dometic 3-way is fused with a 30 amp 12v dc fuse Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 24, 2015 Author Share Posted July 24, 2015 WME, thank you. Is that pretty standard? It doesn't seem like it could vary much. What's the harm in over-fusing a little? Are there components that are sensitive enough that if I used a 20A fuse in place of a 15A or a 30A instead of a 20A that it would cause a great deal of harm? Quote Link to comment Share on other sites More sharing options...
WME Posted July 24, 2015 Share Posted July 24, 2015 Impossible to tell with out looking at the system. In the bad old days, if you couldn't find an electronic problem you over fused the unit and looked for the smoke. Some where you should be able to find the watt rating for the 12v heater, do the math and fuse about 20% over the required amps Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 24, 2015 Author Share Posted July 24, 2015 Funny you should say that, in my bleary-eyed 15th (or so) review of the manual I downloaded a while back I found a small chart buried in the instructions (pic below). It says 14.2A on 12V for the IM-4 models, so with the 20% rule that makes about 20A fuse, am I thinking about that right? Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 24, 2015 Share Posted July 24, 2015 Yes a 20 amp is what you want Quote Link to comment Share on other sites More sharing options...
WME Posted July 25, 2015 Share Posted July 25, 2015 Bingo! Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 25, 2015 Author Share Posted July 25, 2015 So, as mentioned in another post, when I was attempting to chase down the electrical "gremlin" on the 12V side I found that there was a break in the current between two wires. They come out of a small black box with a few other wires labeled with "B1", "B2", "L1", etc. The wires in question are B1 and B2 and have a "switch" between them on the schematic. I jumped the gap with a wire and the fuseable link I mentioned before got hot enough to melt a little bit within just a few seconds but it gets no power when hooked up properly. I have thought of a viable work around if I can't fix it. Wire the 120V outlet through an inverter and run it off the battery while traveling. It says it only pulls 140 watts, not bad. Could get a small 400 or 500 watt inverter, charge batteries, laptop etc. and run the fridge. Then switch to gas while parked. Thoughts? Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 25, 2015 Share Posted July 25, 2015 So, as mentioned in another post, when I was attempting to chase down the electrical "gremlin" on the 12V side I found that there was a break in the current between two wires. They come out of a small black box with a few other wires labeled with "B1", "B2", "L1", etc. The wires in question are B1 and B2 and have a "switch" between them on the schematic. I jumped the gap with a wire and the fuseable link I mentioned before got hot enough to melt a little bit within just a few seconds but it gets no power when hooked up properly. I have thought of a viable work around if I can't fix it. Wire the 120V outlet through an inverter and run it off the battery while traveling. It says it only pulls 140 watts, not bad. Could get a small 400 or 500 watt inverter, charge batteries, laptop etc. and run the fridge. Then switch to gas while parked. Thoughts? A bit small for what you want to do. Generally the ratings are for max inrush output not constant load. A common inverter will do what you want it does not have to be a sine wave inverter so some thing with a higher output will be pretty cheap.If you use an inverter just be certain you have a good frame ground on the high voltage side or plug your MH power cord into the inverter. As far as your 12 volt stuff any thing posted is only a guess with out hands on but a guess would be battery one and two and L1 load. Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 25, 2015 Author Share Posted July 25, 2015 Yeah, not sure how time, energy and money I should put into fixing the 12V side if this work around will function the same way. Probably gonna spring for the pure sine inverter because we will need one anyway for charging the laptop, etc. I don't know how to diagnose a problem with a multi-function switch when it's all tucked into a little box that you have to break to get it open to have a look. I think I burned it when I was testing it, not sure though. Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 25, 2015 Share Posted July 25, 2015 Yeah, not sure how time, energy and money I should put into fixing the 12V side if this work around will function the same way. Probably gonna spring for the pure sine inverter because we will need one anyway for charging the laptop, etc. I don't know how to diagnose a problem with a multi-function switch when it's all tucked into a little box that you have to break to get it open to have a look. I think I burned it when I was testing it, not sure though. No really you don't, laptop power supplies are switch mode supplies they really don't care. Their output is DC there is no connection to line voltage or quality by the time it gets to the computer. Quote Link to comment Share on other sites More sharing options...
RVNOOBS Posted July 26, 2015 Author Share Posted July 26, 2015 OK, SUPER FRUSTRATED NOW!!! A recent road trip revealed no heat in the element on 12V. I just got done taking apart the switch to see if anything was burned, broken etc. It looked fine. I need to clarify this question in my mind. During this fridge testing phase can I switch to 12V without the fridge cooling down first and expect any heat in the element after, say, 60 miles of driving? Is my fridge wired into the vehicle ignition switch? Without running the truck it should do at least something on 12v, right? A little warmth in the element is all I'm looking for, for right now. Quote Link to comment Share on other sites More sharing options...
WME Posted July 26, 2015 Share Posted July 26, 2015 Get an old amp meter and hook it into the circuit. You should see a 15 amps the instant you flip on the DC switch The instruction I've seen say you have 2 switches. Gas or Electric and a 110 or 12 switch Quote Link to comment Share on other sites More sharing options...
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