RV Doctor – Generator Won’t Power Both AC Units

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February 2, 2009

Dear RV Doc,

Recently I was hooked up to shore power that had issues so I switched over to my generator. At one time the generator powered both roof air conditioners, but now it only runs one at a time, just like when I’m on a regular 30-amp service. Could it be something in the power system?

–Merle Reitz, (Lemoore, CA)


Merle, I know you are aware, but I want to remind our other readers that your coach was factory-wired for two installed roof air conditioners, but because the shoreline cord is only rated for 30-amps, you are only able to run one roof A/C at a time. Remember each air conditioner must be on its own 20-amp circuit. There should also be a switch inside, (some are automatic, others manual), that allows you to choose which air conditioner to run while plugged into shoreline. Running both units off the shoreline, as equipped from the factory, is mathematically and electrically not possible; hence the need for some type of switch. The generator, however, adds another dynamic to the mix. It is rated to power both roof air conditioners at the same time.it has enough output capacity. Typically, the rear air conditioner is hard-wired directly to the generator output. On or near the side of the control box on the generator, you’ll find two circuit breakers, one is wired directly to one of the roof A/Cs, and the other breaker is wired to the coach distribution panelboard which protects all the other 120-volt circuits in the coach, including the other A/C. Chances are the circuit breaker on the generator itself is tripped or faulty. And there is the outside chance the air conditioner breaker in the panelboard distribution box is faulty.

(Please feel free to comment, however, please also note that due to the volume of communications I receive from multiple channels I cannot guarantee a personal response in every instance. However, questions of an overall general interest may be considered and published in an upcoming RV Doctor column.)

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  1. Alan

    Hi RV Doctor,

    I presently have a 37″ 5th wheel with 50 amp service. When boondocking I run a Honda eu3000is generator with a 30 amp adapter cord. This is bare bone adaquate for my satellite system, computer, and one of my two air conditioners. I camp in the desert often and would like to run both of my air conditioners. The Honda powers everything just fine as long as I am careful what I turn and off.

    I have read mixed opinions regarding the capability of the Honda eu6500is and its ability to power two air conditioners using a cheater or splitter cord. This generator might solve my problem if I can determine that it can handle the load. So far I find very little information regarding this setup.

    Can you clarify this matter for me?

    Thanks, Alan

  2. David Weekley

    Hi Merle,
    The RV Doctor had some good points but if the generator used to run both air conditioners and now it won’t, you need to do an oil change and a tune-up. How do I know? Experience from the exact same symptoms.
    Need more information? Just email me; I’ll help.

  3. Gary

    Cherly….I’m indeed sorry to hear about the troubles you’ve been having with your travel trailer. It’s got to be draining, I’m sure. Typically, as with any new RV, there will be a “punch” list of items the new owner finds wrong with the RV. Things that somehow slipped by the dealer and the QC department at the factory. Unfortunately, it happens!

    It is far more common that issues are discovered and repaired during the pre-delivery inspection (PDI) at the dealer level. But certainly, if you’ve found other issues, it’s the dealer’s job, on behalf of the manufacturer, to take care of them.

    Troubled coaches with a seemingly endless list of problems are what I call, “Friday afternoon/end of the month” RVs. They are rushed out the door and delivered to the selling dealer where they are discovered and repaired by the dealer prior to delivery to the buyers. Those that do slip through are brought back under warranty and repaired as quickly as possible. This is apparently where you are right now.

    It’s frustrating, I know, but the manufacturer appears to be willing to make the repairs, so chances are the dealer will get them done. Unfortunately, some dealers work faster than others. RV dealers, like RVs, are not created equal. Some are indeed better (read: more efficient), than others.

    You can keep “reminding” your dealer, you would like to take that shakedown cruise soon! Friendly (weekly or daily) update requests to your dealer are not out of the realm of normal in such cases when the RV is “not useable” as an RV for an extended time. In some states, the number of days in the repair shop are added to the existing warranty time frame. Check your state for Lemon Laws as they pertain to recreation vehicles.

    As for that bent axle….chances are it is just fine. All travel trailer axles are manufactured with a slight arch to them. If doubts remain on how the tires wear or how the TT actually tows, have it inspected by a frame and alignment repair shop, rather than an RV service shop. They will have the necessary equipment for the acute measurements needed.

    Regular preventive maintenance is a mandate for all RVs and the only sure-fired way of avoiding operation ills with RVs. I’ve written many articles and produced a few DVDs and videos regarding PM on RVs. Visit http://www.rvdoctor.com for more info.

    Have the TT and the tow vehicle weighed to be sure you are not overweight.

    I wish you good luck as you try to get back on the road come spring!


  4. Cheryl

    Problem: We towed our brand new Passport TT to AK last summer. We babied it….and perpetually had problems…first minor ones –you knoe the small irritating ones that you get over ….and then as though possessed it ‘kicked it up a notch’ until the problems were serious.

    We NEVER abused the TT and were on top of cking all systems…from tires to batteries…. But the Furnace board died, seams leaked, fresh water tank leaked, kitchen sink plumbing leaked, tires wore excessively, AND had to replace the axles. We were under weight…(weighed it before leaving on the trip and after axles were replaced in AK…..It appears that the ‘new’ axles are also bowed(for lack of a better term) and now we are in dispair….I dont trust it…dont like it…and am stuck with it…. We are towing with a Yukon SUV and the weight of the TT is easily under the max for the SUV…

    Keystone seems to be trying to help us… but the time and conversations between the dealer and Keystone/Passport is grinding slow. We had hoped to take another long trip this spring-summer but at this rate we wont have it back to have a ‘shake down’…. or maybe even leave home by April. We wanted to tour Texas before it got hot…… hummm I wonder if we will make it….

    We are experienced RVers…but not TT owners… and I LOVE RVing…but I am tired of this money and time pit. It has been in the shop more than with us…
    Now that I have vented….I am actually asking you several questions.

    What could we have done different or better to have better protected this TT?
    Has other people had these problems with TT or Passports?
    What can we do to prevent this from future trips?
    We would upgrade the axles if that would help…. Any ideas at all?
    Please advise if you have clues!

    This is one huge lemon killjoy… and I am generally very upbeat…but this is a test that we are failing.

    thanks for your attention.