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Coleman AC Intermittently only 'Hums'

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  • #1

    Coleman AC Intermittently only 'Hums'

    Our bedroom Coleman Mach AC will sometimes work, and sometimes it just 'hums', fan not spinning. When the ac works, it works well for several days and then not for a few days. All the capacitors, compressor windings and the thermal protector all checked out ok. Wire and wire connections all good. Been parked for about 2 months in southern TX.
    Has anyone else had this problem and how was it resolved?

    2018 Coleman Mach 10
    Model #45253-8792

    Thanks,
    Rudy
    Rudy
    South Dakota
    2019 GMC 3500HD Duramax SRW
    2018 Reflection 337RLS
    Tags: None
  • #2
    Rudy
    As you know the fan motor and compressor are separate entities, so the fan not spinning shouldn't be connected with a physical problem in the compressor. At least that's my thought process as of right now...so I'd eliminate the compressor for now as a suspect.

    According to a wiring schematic in my files (ignore the EasyStart portions) there is a separate Fan Capacitor in a Mach 10. But...a capacitor is typically good or bad. Easy to swap--don't you have two a/c's on your 337? Swap the fan capacitor and see if the problem follows. If it does, replace the capacitor. If it doesn't, I'd suspect the motor windings have developed a "dead spot". When the motor stops in the right (wrong!) spot it has a hard time getting past it.

    Howard

    P.S. Note to other readers--I know Rudy is a trained RV technician (we both went to the same school) so my comments to him are written on that basis.

    Click image for larger version Name: schematic.jpg Views: 354 Size: 118.4 KB ID: 102643
    Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

    2017 Ford F-350 DRW, '19 315RLTSPlus
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    • #3
      Don't know how you tested the fan capacitor, you can watch a dvm change resistance, but that really only tells you it's not open or shorted. Assuming this is how you checked, it doesn't really prove out the start capacitor.
      I would take apart the fan wire nuts on red white and black and verify good connections. I would then pull apart the plug assy a visually check the connector for corrosion.
      If that checks out you need to determine whether it is motor or cap. If you were lucky enough to get this to 'hum' when troubleshooting, I would spin the fan blade with a stick. If the motor spins up...replace the cap.
      If it doesn't spin up, change the motor.
      My money is on the cap. Or motor bearings are deteriorating. They can sometimes appear like an electrical issue. nah...I'm sticking with the cap being the problem.

      Rudy good to have an RV tech stop by the forum every now and then...don't be a stranger.
      2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
      Electricians were created because engineers need heroes too....
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      • #4
        From the inside of the RV, and inside the ac, there is a control box, check the wire connections there. If I remember correctly at last years Rally an owner was having a similar issue and one terminal on the control box was loose fitting and the terminal on the circuit board was not in good shape, change the control box and all was good.

        Brian
        Brian & Michelle
        2018 Reflection 29RS
        2022 Chevy 3500HD
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        • #5
          Originally posted by Country Campers View Post
          From the inside of the RV, and inside the ac, there is a control box, check the wire connections there. If I remember correctly at last years Rally an owner was having a similar issue and one terminal on the control box was loose fitting and the terminal on the circuit board was not in good shape, change the control box and all was good.

          Brian
          Rudy -- Brian has a good memory! In that particular case (if my memory is intact...questionable...) changing fan speeds made a difference. Does changing from low to high (or high to low) get it to work?
          Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

          2017 Ford F-350 DRW, '19 315RLTSPlus
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          • #6

            Just having a snack while we wait for Rudy to tell us what fixed it, or if it is still a problem.
            2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
            Electricians were created because engineers need heroes too....
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            • #7
              Originally posted by Scott'n'Wendy View Post

              Just having a snack while we wait for Rudy to tell us what fixed it, or if it is still a problem.
              DW Andi probably has Mike (Rudy) Rudy very busy working on honey do things......or maybe just enjoying themselves at a winery or craft beer brewery enjoying awesome IPAs !
              I know you will get things corrected Mike.....please keep us posted. Hope you guys are doing well.

              Dan
              Dan & Carol
              2014 303RLS Reflection #185 (10/2013 build)
              2012 Silverado LTZ Crew Duramax 2500HD - 2700/16K Pullrite Superglide
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              • #8
                Originally posted by Rudy View Post
                Our bedroom Coleman Mach AC will sometimes work, and sometimes it just 'hums', fan not spinning. When the ac works, it works well for several days and then not for a few days. All the capacitors, compressor windings and the thermal protector all checked out ok. Wire and wire connections all good. Been parked for about 2 months in southern TX.
                Has anyone else had this problem and how was it resolved?

                2018 Coleman Mach 10
                Model #45253-8792

                Thanks,
                Rudy
                howson Scott'n'Wendy Country Campers

                The only time my AC has acted like that was intermittent low voltage. My EMS was giving a warning too. Rudy did you perhaps have a chance to lopk at the system voltage or amp draw when it occurred. I did not see anything posted on that and if I missed it sorry.

                Just thinking out loud here.
                Keith
                .
                2018 Reflection 150 Series 220RK 5th whee, Star White 2022 F350 King Ranch CC Long bed (HAL) (CCC 4062lbs), B&W 25K OEM Companion,. SteadyFast system, Trailer reverse lights, rear receiver spare tire holder, storage tube, sumo springs, Victron MultiPlus 12/120/3000, Solar, Custom 6K axles upgrade, and other modifications.
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                • #9
                  After checking everything over, did replace the fan motor capacitor with a new capacitor the other day and so far it's working fine. Thanks for everyone who chimed in.
                  Rudy
                  South Dakota
                  2019 GMC 3500HD Duramax SRW
                  2018 Reflection 337RLS
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