Coast Resorts Open Roads Forum: Coleman Mach 15 problems......need some help troubleshooting
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 > Coleman Mach 15 problems......need some help troubleshooting

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Joined: 06/05/2023

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Posted: 06/05/23 06:51am Link  |  Quote  |  Print  |  Notify Moderator

Hello all to all.

Hope someone kneadable with these coleman mach or just basic mobile AC units can point me in the right direction.
2017 Heartland Trail runner camper trailer model 27fqbs owned for about 1 year, the AC stopped working on a hot day during camping trip.
The day prior made a barely noticeable whine noise when the ac would kick one.
When it did go out, fan would be on, but would not turn on during the AC selection.
After coming home from trip, I began trouble shooting. Checked the breaker, removed and checked the fuse all good.
Played around with thermostat, opened the top mounted units covers everything looked in working order.
So my thinking lead me to believe the capacitors might have gone bad, after all they are inexpensive to replace to see if that would fix the problem. Located them, inspected them no visual damage/burn marks/foul smells – nothing. Did some research. Inter-webbed and theytubed a bit. AHA! It could be the capacitors, but ofcourse!
Logged on to Gerber, picked up a pair with the same spec for $25, installed them in the same order with the same wire positions.
After turning on the ac function, I hear the ac unit turning on it’s blowing the house 110v breaker.
Great….. So what now?
I doubt it’s the thermostat. Possibly the compressor going bad and tripping breaker?
Is there another electrical junction that I’ve missed?
I wonder if it’s the main circuit board having a short.
Do the symptoms I’ve explained above like something you have experienced?
Please spare comments like: You should take it in to a dealer/professional ac service center. Thank you

CA Traveler

The Western States

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Posted: 06/05/23 08:05am Link  |  Quote  |  Print  |  Notify Moderator

Anothe AHA moment would be to post the A/C make/model. Have you checked the AC voltage with a heavy load like HW? You could also check voltage at the A/C. Low voltage is more common in the summer.

Otherwise as a non expert it sounds like the compressor.

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Posted: 06/05/23 10:24am Link  |  Quote  |  Print  |  Notify Moderator

Some questions:

When first experiencing the problem, were you on park power or generator power?
What size is the air conditioner?
Please define ‘house breaker’ and rated amperage…



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Joined: 09/06/2008

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Posted: 06/05/23 01:42pm Link  |  Quote  |  Print  |  Notify Moderator

You may have plugged your motor home into a home outlet that is also on a circuit with another appliance. That would cause the home breaker to trip if the total load on the breaker was exceeded. Plug your motor home into an outlet with nothing else drawing power from that circuit. Make sure to use a heavy-duty adapter and short heavy duty extension cord. Try to start the AC again.

If it still trips the breaker, replace the capacitors with the original capacitors. See if the original problem returns. If it works, you may have wired the replacement capacitor incorrectly. When replacing capacitors, polarity marking must be observed, not the location of wires.

Your air conditioner may have low voltage protection and turns off when voltage is to too low. In a camp ground, many people using air conditioners at the same time would causes the camp's AC power to drop.

If the compressor still does not turn on, check voltage to the compressor. If no voltage, trace it back to where it loses voltage. If voltage is good, the compressor would be defective. Good luck with your trouble shooting.


Carrolton, Texas

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Posted: 06/06/23 03:43am Link  |  Quote  |  Print  |  Notify Moderator

1. Do you have a 30 amp RV plug at home for the RV?
2. House breaker, I assume your residential house breaker. WHAT AMP is it?
3. Does the fan come ON if you select fan only?
4. IF the fan comes ON, how long before the House breaker trips?
5. The Tstat will NOT be the problem
6. The Upper circuit board will NOT be the problem, unless you remove the cover and see obvious burned wires/circuits.
7. If the fan runs, does the compressor attempt to start or hums?
8. You need this tool to see what the amp reading is when the compressor tries to start.

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