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vexter0944's avatar
vexter0944
Explorer
Aug 18, 2014

Coleman Mach 15000 BTU A/C Issue - Electrical in Nature

I have a mobile catering/vending rig built in 2012. It has a Coleman Mach 15K A/C unit for keeping us cool while cooking/serving.

Up until a couple of weeks ago, it has been perfectly fine - I use a Honda EU6500is series generator to handle everything in our trailer from fridge, to A/C to warming units and have never had a problem with overloading the generator at all.

A couple of weeks ago, I setup like normal and every time the A/C would kick on - the generator would show overload and shut off A/C current. When I moved a few items off to a second generator all was fine, but the EU6500 was running like it had some crazy load attached to it - which it didn't.

I thought maybe something had happened to our trusty EU6500, so I purchased a Yamaha generator (EF3000iSEB). (not meant to 'replace' the Eu6500 - just as a secondary backup and as a smaller use generator for when I don't need to run steam tables etc - like when I'm catering - instead of lugging around the beast I can bring this and have 30A service for lighter cooks/jobs.)

I tried using it this weekend on the 30A circuit and was only running some lights and small stuff and the Coleman A/C. The minute the A/C tried to kick on - man it looked like a poltergeist had moved in to the trailer - lights flickering (fluorescent) and it killed my kill-a-watt meter. So I re-adjusted (since the show had to go on because I was catering) and got some power from an outlet (20 amp) and moved everything off the Yamaha to shore power except for the A/C - now when the A/C would kick on the generator would run full tilt when I know it only needs like 18A or so to 'run' (I realize the need for more when it's starting..) - but I have one of the EMS-HW50C units installed, so I've seen in the past when on 50A 220V shore power how many amps I pull when operating etc.

So I think and am pretty sure, something is going on with the Coleman A/C unit because the problems only arise on both generators, when the A/C unit kicks on.

any ideas of where I should turn or try to look to fix this? I'm NOT a mechanic, but if it's just a part to replace/check - I can get that done. If not - I don't want to get screwed for a new A/C unit if I take it in to be looked at.

Any help/ideas would be much appreciated!

Thanks!

29 Replies

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  • ryanw821's avatar
    ryanw821
    Explorer
    Aug 18, 2014
    vexter0944 wrote:
    I don't think this would be a food/grease issue - we use smokers and they're on the back deck and we don't cook inside - the inside filter is clean, check that routinely. But I will certainly check it all out - it's a good idea..and maybe the smoke did finally get to it and I don't know it...


    Well even smoke soot can build up, I really do hope it is something simple you can resolve easily :)
  • dougrainer's avatar
    dougrainer
    Nomad
    Aug 18, 2014
    vexter0944 wrote:
    MEXICOWANDERER wrote:
    A bad capacitor can make an AC operate like Jack Nicholson had the wheel. Check starting current of BOTH the compressor AND the motor that powers the condenser and evaporator fans shaft.

    Manufacturers should be FORCED TO make the so-called "Hard Start" capacitor standard equipment. OEM can buy stuff for about 20% of what we mortals are forced to pay.


    Is there a way someone like me, with only a multimeter can check this and if so, how? Otherwise, should I just take it to a shop to have this checked?


    The model number will tell you if it has a hard start capacitor. BUT, RVP only specs out hard start capacitors for Major OEM RV makers, when asked. Small van conversion companies or RV after market suppliers will not stock RVP AC units with the hard start capacitor. SO, you need to install one, especially if you are using a NON RV generator for power. Using the type Genset you have, the Hard Start Capacitor will make all the difference in the world on start up. As to being "forced". BS. The Non hard Start units will function just fine with the intended 120 supply either from Shore or from a RV designed Genset. THAT is the correct answer. If you USE a RV designed genset, then the Hard Start is not needed. Use another type genset or power supply, then YOU need to install the required updated Capacitors. Why should the majority have to pay extra for the small minority needed equipment?????? Doug
  • ryanw821's avatar
    ryanw821
    Explorer
    Aug 18, 2014
    MEXICOWANDERER wrote:
    A bad capacitor can make an AC operate like Jack Nicholson had the wheel. Check starting current of BOTH the compressor AND the motor that powers the condenser and evaporator fans shaft.

    Manufacturers should be FORCED TO make the so-called "Hard Start" capacitor standard equipment. OEM can buy stuff for about 20% of what we mortals are forced to pay.

    MEXICOWANDERER has a good point about hard start capacitor, it will help even out surge starting the AC, but the fact that its starting it and running for a while leads me to believe that's probably not the culprit here. If it was the capacitor, it would most likely bog down and overload the genny immediately.

    I am HOPING it's just dirty for your sake, because if it's not that I have a feeling it's something that likely needs professional service like low refrigerant :(
  • vexter0944's avatar
    vexter0944
    Explorer
    Aug 18, 2014
    ryanw821 wrote:
    vexter0944 wrote:
    I'll take the shroud off and peek - I'd be surprised if it's too dirty as it's stored in a lot with no trees etc - but then again, I've been surprised before!

    Thanks for the input and idea! I appreciate it! If it is dirty, can I just hose it off? I've never cleaned one before.

    Keep em coming if you have ideas - thanks!!


    Since you say its a catering/vending rig, you could be dealing with grease or food particulate build up (especially if there's a roof exhaust vent near the AC unit), might not just be tree debris, that's just whats common for me ;)

    Yeah, I would pick any loose crud out of it by hand, and hose out the rest on the roof side (carefully, I wouldn't go overboard, I don't know how tightly your's is sealed), on the inside I would check the filter (probably washable kind) to be sure its clean as well, any kind of obstructions on condenser or evaporator coils can cause issues with overheating and overloading.


    I don't think this would be a food/grease issue - we use smokers and they're on the back deck and we don't cook inside - the inside filter is clean, check that routinely. But I will certainly check it all out - it's a good idea..and maybe the smoke did finally get to it and I don't know it...
  • vexter0944's avatar
    vexter0944
    Explorer
    Aug 18, 2014
    MEXICOWANDERER wrote:
    A bad capacitor can make an AC operate like Jack Nicholson had the wheel. Check starting current of BOTH the compressor AND the motor that powers the condenser and evaporator fans shaft.

    Manufacturers should be FORCED TO make the so-called "Hard Start" capacitor standard equipment. OEM can buy stuff for about 20% of what we mortals are forced to pay.


    Is there a way someone like me, with only a multimeter can check this and if so, how? Otherwise, should I just take it to a shop to have this checked?
  • ryanw821's avatar
    ryanw821
    Explorer
    Aug 18, 2014
    vexter0944 wrote:
    I'll take the shroud off and peek - I'd be surprised if it's too dirty as it's stored in a lot with no trees etc - but then again, I've been surprised before!

    Thanks for the input and idea! I appreciate it! If it is dirty, can I just hose it off? I've never cleaned one before.

    Keep em coming if you have ideas - thanks!!


    Since you say its a catering/vending rig, you could be dealing with grease or food particulate build up (especially if there's a roof exhaust vent near the AC unit), might not just be tree debris, that's just whats common for me ;)

    Yeah, I would pick any loose crud out of it by hand, and hose out the rest on the roof side (carefully, I wouldn't go overboard, I don't know how tightly your's is sealed), on the inside I would check the filter (probably washable kind) to be sure its clean as well, any kind of obstructions on condenser or evaporator coils can cause issues with overheating and overloading.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Aug 18, 2014
    A bad capacitor can make an AC operate like Jack Nicholson had the wheel. Check starting current of BOTH the compressor AND the motor that powers the condenser and evaporator fans shaft.

    Manufacturers should be FORCED TO make the so-called "Hard Start" capacitor standard equipment. OEM can buy stuff for about 20% of what we mortals are forced to pay.
  • vexter0944's avatar
    vexter0944
    Explorer
    Aug 18, 2014
    I'll take the shroud off and peek - I'd be surprised if it's too dirty as it's stored in a lot with no trees etc - but then again, I've been surprised before!

    Thanks for the input and idea! I appreciate it! If it is dirty, can I just hose it off? I've never cleaned one before.

    Keep em coming if you have ideas - thanks!!
  • ryanw821's avatar
    ryanw821
    Explorer
    Aug 18, 2014
    If its dirty and clogged up, it will draw A LOT more power trying to run and cool, I would get up on the roof and remove the shroud and check that its not full of leaves, dirt, dust, or a big one in my area cotton from the cotton wood seeds.

    I have to clean out the AC wall-units in my house yearly or they will start doing the same thing (drawing too much power popping their breaker) from all the cotton wood crud in them.

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