Apr 8, 2013 - Appliances, Fridge, Technical    12 Comments

My Fridge Doesn’t Like AC

Last night, I managed to blow the breaker in the house. I was barely using any power. I had tested the outlet prior to plugging in and knew Ms. Cinnamon never had any trouble with it when her rig was plugged in.

All I had done was switch the fridge to AC. So it looks like my fridge woes while on FHU at Hidden Valley were not a one-time thing. My fridge is no longer happy about running on AC.

I’m so tired of troubleshooting that I’m tempted to just ignore this problem. But if I’m having trouble on AC, trouble on propane is sure to follow…. I’ll wait until I have easy access to the a breaker before I start doing a bunch of tests. I did pull out my manual and none of the troubleshooting tips look too promising. I’m seeing a lot of ‘not user serviceable’ mentions…

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12 Comments

  • I hope this turns out to be a fix you can do or at least an inexpensive service call if it gets to that.

  • If it still works on propane, it will almost certainly continue doing so. Tripping the breaker on AC is most likly a shorted heater coil or a wiring short, check for damaged wiring and replace if you find any.

  • This doesn’t sound like a refrigerator problem. Chances are the breaker tripped because there was too much power being used on the circuit.

    OK, it’s nominally 20 amps, but you’re assuming your rig is the only thing plugged into that circuit. This is almost certainly not the case. It’s not like a campground power hookup–you don’t have a monopoly on the power in that circuit. You’re sharing it with the house.

    Your host probably has other things plugged into the circuit, which may well serve one or more rooms in her house. She could be running anything from light fixtures to a toaster oven or a vacuum cleaner from that same circuit, and your rig’s power usage is added to the existing usage. The fact that your host never had a problem when her rig was plugged into that outlet could merely be because she wasn’t in the house and in the RV at the same time, so she wasn’t running appliances in both places.

    Let’s talk numbers. Your fridge draws a minimum of 3 amps (360 watts) when running on AC. Your converter, if it’s a factory-standard one, can draw as much as 5 amps (600 watts) while charging your batteries. In short, those two devices alone could be putting an 8-amp load on that circuit, in addition to whatever loads that you don’t know about are in use inside the house. It’s easy to see how a breaker might trip. Suggestion: if your converter is charging your batteries, turn it off. Let your solar panel do that job.

    There’s more. You didn’t say how you’re connected to the 20A outlet on your host’s house, but this “driveway camping” situation usually involves extension cords. A very common thing to do is to use a 30A-to-15A adapter at the end of the regular 30A shore power cord, and then run a 15A extension cord from there to the house.

    Doing that forces power to go all the way through the long, skinny 15A cord–a bad idea, and one that increases the likelihood you’ll trip a breaker in the house. Instead, use a heavy-duty 30A extension cord to get the length you need, then add the 15A adapter at the very end, where it plugs into the house. 30A RV extension cords are sold by most Walmarts in the RVing department (part of the automotive section).

    I hope these suggestions help. If worse comes to worst, you may have to just run the fridge on propane for the duration. I’ve been in this situation a few times, and it can be frustrating. But it almost certainly does NOT mean there’s anything wrong with your fridge, so you can at least take comfort in that knowledge. 🙂

  • Andy, this outlet is on a dedicated circuit for the RV pad. There is no extension cord involved.

    I don’t think it’s a coincidence that I have had a problem with the fridge while on AC twice in just a few weeks.

    Folks, Andy gives good information. 😀

  • Thanks, Blars.

  • Looking at the incoming amps on my RV’s power management system, I can see that my 8 cubic foot fridge draws about 2 A from the AC line when it’s running. Yours is probably similar.

    If you’re not using much else in the coach and you’re popping a breaker, it sounds like some sort of short circuit in the refrigerator’s AC heater.

    I’m not sure what exact model of fridge you have, but this might help with troubleshooting. It’s a copy of a service manual for dometic absorption refrigerators.

    http://webspace.webring.com/people/jv/vintage_campers1/Dometic_Refr_Service_Manual.pdf

    Page 44 in particular talks about how to use your ohm meter to check the resistance of the heating coil. You can probably also check the resistance of the whole unit on the 120V circuit. I’m guessing it ought to be about 85 Ohms, more or less the same as the heating coil by itself. If it’s a lot less than that, you’re going to draw too much power.

    This site has an assortment of manuals for refrigerators ( lots of other RV tech info there, too ) – http://www.rvtechlibrary.com/appliances/refrig_manuals.htm
    You may find something in there that gives more information on the diagnostics of your particular fridge, but the techniques for testing the heating coil is pretty much the same for all makes/models.

    I agree with Blars that the propane will probably continue to function.

    Please make sure that there is no 120V power to the refrigerator when you work on it! ( I’m sure you know that, but it’s dangerous ).

    I hope this helps!

  • Yup, about 2A since it’s about 20AH when I’m on 12V power. I have a Norcold 3-way. Thanks for that link, it’s more useful than my manual!

    I can unplug my fridge right in its compartment in addition to cutting power to it from a breaker. So no worried about me doing anything foolish. 😉

    Thanks for this info, I’ll work on the troubleshooting when I’m closer to the 120V breaker.

  • Rae – when I had an RC like yours (with Norcold fridge), I had some similar problems and I replaced the 3 amp fuse located in the exterior service entry, near the mother board – seemed to have solved the problem. Website below gives you a picture of the fuse I’m referring to….good luck

    Mike
    (PS – I like Andy’s explanation better than mine!)……

    http://www.americanrvcompany.com/Norcold-61654622-Refrigerator-Part-3-Amp-Fuse-Trailer-Camper-RV_p_4198.html

  • Mike, I have a fuse like that handy, so I will go check the resistance on the existing one, thanks!

    Andy’s info is great as always, but definitely out in left field for my current situation. 🙂

  • Sorry, Rae–I didn’t know you were plugged into a dedicated circuit. Odd that your host would install an RV hookup limited to 20 amps, when most RVs nowadays require either 30 or 50…

  • My host didn’t set up the hookups. The outlet wasn’t necessarily meant to be used for an RV, but now that’s its sole purpose.

    BTW, I believe it’s a code requirement for exterior outlets to be on their own circuits.

  • […] Since leaving the beach, I had problems with my fridge set to the AC (shore/120V power), both on 30A at an RV park and 15A in a driveway. […]

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