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Old 07-05-2019, 06:41 PM   #1
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A/c issue. 2018 tt

Hello family!

Recently was at a state campground running 30a service to my 2018 puma tt. On our last day the a/c quit. It’s a Coleman Mach AC. On an 85 degree day. Still had power to the trailer. Didn’t trip main 30a but it tripped the designated 20a a/c breaker. (Didn’t trip the park power pedistal either.)

It would not reset. I tried multiple times flipping it all the way off then on. Instantly it would trip. The a/c is switched off at this point at thermostat. I got home plugged into shore power using an extension with a dog bone adapter (only thing I have) and flipped the a/c breaker. It stayed on.....

But it tripped the breaker that supplies power to the outlet I plug in to!!!! A/c is still off at the thermostat at this point. Hasn’t run, just keeps tripping breakers.

Thought it was maybe low power supply to the park but it stays on at home as I mentioned. My wife mentioned a “burning plastic “ smell the day prior too this happening...... any help or suggestions appreciated?

I have already...
Checked wire tightness at the breaker in the trailer.
Tried it with all other power off including fridge.
Switched outlets at the park.


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Old 07-05-2019, 07:03 PM   #2
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If your wife smelled burning plastic, you likely developed a short or your fan or compressor motor burned out. If it's a short, check your breaker box and connections at the AC for any stray or loose wires. The fan would be replaceable I believe, but the compressor likely is not. If the AC is still under warranty, would probably be a good time to call that in.

Cut it 3 times and it's still too short...

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Old 07-05-2019, 07:32 PM   #3
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Would that cause breakers to instantly trip even with thermostat set to off?
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Old 07-05-2019, 07:35 PM   #4
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I see my fan spin when itís windy out. I know that wasnít seized up.

Was also thinking the capacitor?
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Old 07-06-2019, 03:13 PM   #5
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My son in law had similar issue with their water heater. Wiring at the breaker was loose. As amperage is pulled wiring will heat up. It will expand and contract. Unplug completely from shore power and check you leads going into the breaker. I hope it is something that simple. Best of luck to you and your family and happy camping.
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Old 07-06-2019, 03:34 PM   #6
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Sounds like low voltage. An AC unit draws more current as the voltage goes down. They draw around 50-60 amps momentarily on startup and if the voltage is too low, the inrush current can go up and trip a 20 amp breaker. Low voltage can also result in permanent damage to an AC unit, even *if* it seems to be running fine. Could be a bad capacitor but if working fine at home won't be the cause.

I'd get a voltmeter to have permanently inside so you know what the voltage is wherever you are camping. An LED type is best. Even better is an EMS unit that will automatically shut you down on low voltage and also some other electrical anomalies. If voltage gets below 105, you want to stop running an AC unit.

Running an AC unit on 15 amps at home is not a good idea, especially if you are using a small gauge extension cord in addition to the shore power cord.
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Old 07-07-2019, 09:20 AM   #7
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I agree to check capacitor and wiring to capacitor, this will smell like plastic if it fails and melts the top area. Relatively cheap to replace. To test your AC fan just turn on the fan at your thermostat if this works it is not associated with fan. Some compressors go all at once but many times show some kind of signs such as noise, poor cooling, hard starting, etc. before going bad.
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Old 07-07-2019, 10:09 AM   #8
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Originally Posted by Csvt18 View Post
Would that cause breakers to instantly trip even with thermostat set to off?

The thermostat is low control voltage there is still 110V power at the AC unit.

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Old 07-07-2019, 10:37 AM   #9
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AC capacitors go bad all the time in AC fans and AC compressors. Much more likely to be that or if it has a start relay then they go bad instead of the compressors.

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