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gillman's avatar
gillman
Explorer
Aug 01, 2017

Champion 3500/4000 Generator won't run AC unit?

Need some advice. Many years back, we had a travel trailer and I purchased one of these low-cost gensets. It was a little loud but sure ran the 13,500 BTU AC unit and other little items in the camper just fine. I used it extensively after Hurricane Ike for power to the house as well. I finally just wore it out so I decided I would buy another one just like it and simply leave it in the box until I needed it. (I did pull it out and put oil in it but never started it - didn't want gas in it...). This was probably 4 years ago so it has just been sitting in my shop.

A few weeks back, we lost power at home so I thought "well, we can sleep in the 5th wheel tonight and at least have Air Conditioning". I went to the shop and gassed up/powered up the Champion generator (started very easy). The 5th wheel has a 15,000 BTU Dometic AC unit but the generator is still within the specs to handle the bigger unit. I let the generator run for 5 to 10 minutes or so and plugged in the RV and flipped the switch for 120v. (It has a 30 amp RV plug on it). When I turned the thermostat on inside the 5th Wheel, it bogged down the generator so much (almost dying due to the load), that I quickly turned off the Thermostat as I was worried about hurting the AC unit. I tried it again a few minutes later with the same result so I have not messed with it since.

I have not contacted Champion yet. There is a "800" support line to call and I likely will but I thought I would ask some of you your thoughts. While the unit is "brand new" from a running point of view, it is now certainly out of any warranty period I am sure from Champion's point of view.

The AC unit is just fine when plugged into shore power.

Thoughts on this generator and why it would do this? In hind sight, I should have tried it out when I first brought it home but I didn't want carburetor issues even though I use Stabil in all my small engines.

Thanks in advance for your advice!

19 Replies

  • I use a Champion 3100 to run my 15k BTU AC and never had any issues. Like previously stated some other big draw things must have been on at the same time. I know I can run my TV and lights plus charge my batteries while the AC is running.
  • The Champ should chew through this load with no difficulty. Yes, you may need to monitor other loads, but the 3500/4000 has whopping surge capability and your AC isn't even in rotor lock yet.

    I would not hesitate to call Champion tech support. They probably won't hand you a free replacement, but once you troubleshoot here, isolate extra loads, and if it still isn't working, then you should tell Champion. These simple units are designed to sit around for years until there's an emergency and then start on the first or second pull and perform perfectly.

    Er, did you put oil in it?
  • gillman wrote:
    I am not sure how to disable the converter. Is that one of the breakers?
    That's likely, yes.

    When you first plugged in to the gen, did it 'bog' or hesitate at all, like something else was on? Which outlet are you using?
  • I have a Champion 3500/4000 and it will run my 15K AC. I turned off everything but the converter, but the battery was fully charged. Ran it for about 2 hours fine just to test it before hurricane season. It was about 90 degrees at the time. I just turn off the fuel supply to run all gas out of the carb on my small engines that will be sitting a while. Never a problem.

    You should be able to run the AC. It could be that the starting capacitor in your AC is bad. This could stop the generator but the shore problem would have no problem overcoming it. It could also be a problem with the generator. Test the generator by running hair dryers and other high draw appliances.
  • garyemunson wrote:
    How big is the generator?


    Sorry... it was in the subject line and not in the message itself...

    3500/4000
  • Yes, that could be a very valid point....I am not sure if all the other items were turned off -I know the fridge was but not especially sure of the water heater... I know they drag a lot of power.

    How do I turn the converter off from charging the batteries? I can plug it in to shore power for awhile before trying again so the batteries are charged but I am not sure how to disable the converter. Is that one of the breakers?
  • 3,500 watts is only 3,500 watts. Water heater, converter, refrigerator, etc. can reduce the available power to 2,000 watts. Turn everything else off and try it again. Report back.
  • Had your 5th wheel been plugged into shore power up until the Genny test?
    If your batteries were low on the 5er the converter would have been trying to recharge, possibly at a high rate depending on the converter you have. Also you may have had the refrigerator trying to start at the same time.
    Try turning the converter and everything else off and starting the AC then and if that works, after it has setteled in to run the AC turn the converter back on.

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