Disaster strikes! 3-way fridge wiring question

Discussion in 'Wiring' started by Greg H, Jul 29, 2020.

  1. Greg H

    Greg H New Member

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    Hi everyone! Somewhat long-time lurker, first time poster. Last summer, we bought a new-to-us 2012 Rockwood 1940LTD. This past weekend, we experienced a blowout on the drivers side tire, which tire out the plastic (stapled in???!!!) wheel liner. I guess the wiring is just draped over the liner, because a bunch of it got wrapped around the axle.

    Fortunately, it looks like only the lighting, 12v fridge and heater/thermostat wiring was damaged. I’ve managed to fix the wires for the interior and exterior lights, and don’t use the heater, so that’s not urgent.

    the only thing I’m a bit unsure of is the 12v fridge wiring. There are 2 black wires which now terminate in the wheel well. I’m guessing this is just 12v positive and ground, and they should just tie in with the rest of the 12v wiring. However, this is just a guess and I’m not completely sure which is which is positive or ground. Can anyone confirm? See pic below (and yes, that is a hole caused by a piece of tire busting through the floor)

    thanks!!!

    Greg
     

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  2. Anthony Hitchings

    Anthony Hitchings Well-Known Member

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    frig wire are not polarized unless you have electronic controls. A Dometic 2193 does not. so it depends on your frig.
     
  3. Greg H

    Greg H New Member

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    It is the 2913, so no polarization - perfect, and thank you!
     
  4. IndyRick

    IndyRick Member

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    I taught physical science for 29 years, and I've never heard of a DC circuit that wasn't polarized. Please use a multimeter (inexpensive ones are fine, and readily available) to confirm positive and negative on your wires. It's possible that the 12v positive supply is the only 12v wire going to the refrigerator since the frame of the refrigerator could be connected to the frame of the PUP to provide the negative return.
     
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  5. Greg H

    Greg H New Member

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    Slightly embarrassing question, but how do I confirm which of the 2 wires coming from the fridge is positive and which one is negative?
     
  6. MNTCamper

    MNTCamper Well-Known Member

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    You'll have one feed on the wire and the other grounded to the frame. You'll get no voltage on the return, or ground wire and 12+ volts on the feed wire (positive). That assumes that you are providing 12V to the wire set at that point either through battery or the converter.
     
  7. GreyFox

    GreyFox Well-Known Member

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    Measure with a voltmeter - as an RV owner you should always have one on hand.
     
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  8. IndyRick

    IndyRick Member

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    Not an embarrassing question at all! Before I answer, I need to confirm your question. Are you asking about disconnected wires that are attached only to the refrigerator, or are you asking about the wires that supply power from the PUP to the refrigerator?

    I just went back to look at the photo you posted initially. Both wires #1 & #2 look like 12v positive wires to me. I would also expect both to trace back to the PUP wiring system.
     
    Last edited: Jul 31, 2020
  9. Greg H

    Greg H New Member

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    Thanks! I’m talking about 2 wires from the refrigerator, which is #1 and #2 as labeled. Both wires from the power supply got ripped out when the tire blew . So I’m looking at 2 black wires leading from the refrigerator control unit.
     
  10. IndyRick

    IndyRick Member

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    Greg - There's no way I know to determine the power requirements of a device just from the wires attached to it. Depending on the model, RV refrigerators are typically powered by either 12v or 110v electricity, or LP gas, but only 1 of those at a time. In your photo, you show the left-hand side of the control panel and the bottom of a 110v outlet that is typically used for the 110v power supply. You will need to trace the wires to the switches in the control panel to start to figure out what's what. The 12v supply may be just a single 12v positive wire, but the 110v supply will be 2 wires and a plug that would go in the 110v outlet.
     
  11. Greg H

    Greg H New Member

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    Hey guys,

    thanks for all the advice. I’ve decided to leave the 12v fridge wiring disconnected for the time being as I literally never use it. The good news is that with a little effort, I’ve managed to repair everything else better than new! All the other wiring is fixed, I repaired the chipboard flooring, had the bent frame piece replaced by my neighbor and made a new wheelwell out of sheet metal, which I then seam sealed and spray painted with automotive undercoating. I framed the wheelwell hole with wood on the inside of the camper, so that I could drill into real wood rather than the chipboard flooring. Much stronger than the original staples in plastic liner! Back camping this weekend!
     
  12. IndyRick

    IndyRick Member

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    Outstanding! Adapt, improvise, & overcome is not just for the Marines (and "never give up, never surrender" not just for Galaxy Quest). They also apply to PUP ownership.
     
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  13. rabird

    rabird Howdy!

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    As you can see from the install directions POLARITY does not matter, like a light bulb, the 12v heating element gets hot no matter which POLARITY is used. Just wire up the 2 wires.
    fridgewire.jpg

    12vDC, A resistor or light bulb in a circuit does care about POLARITY. When they work 'backward' one gets HOT and the other emits light, now a furnace fan would 'run' backward with reversed POLARITY.

    This portal has witnessed folks with old PUs hook up a battery backward to have the lights work fine but the furnace would not light since the sail switch never closed, newer PUs have reverse polarity fuses.
     
    Last edited: Aug 4, 2020
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  14. IndyRick

    IndyRick Member

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    Hi rabird - That makes perfect sense! While I've taught the gas expansion refrigeration cycle for years, I never looked into how an absorption refrigerator worked. Thanks for the info!
     
  15. Greg H

    Greg H New Member

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    Instructions? Who woulda thought? Lol!! I figured as much as there was no discernible way of telling which wire is for positive or neutral, which makes zero sense if polarity matters. Not that I haven’t seen stranger things...
     
  16. Anthony Hitchings

    Anthony Hitchings Well-Known Member

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    its a resistance heating element and a switch - its not polarized

    and

    it should not be connected to any frig frame

    and

    frig flange is secured to wood cabinet and wood floor
     

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