Hello All,My Coleman Mach A/C failed the other day. The fan works but when you turn on the A/C it immediately trips the circuit breaker. After pulling the cover I noticed the wire and connectors on top of the hard start was burnt. I replaced the hard start and the compressor relay with stock parts from my local RV dealer. After installing the new parts, I turned on the A/C and it ran for about 3-4 seconds and then tripped the breaker. I reset the the breaker turned the fan on a nd then turned the A/C on and the breaker tripped immediately just like it was wasw before. Any suggestions what my problems could be? The A/C unit is only 5 years old and was working fine up to this point.

Are you referring to the 'hard start' as the start capacitor? My first thought was the start-cap has gone bad.Can you spin the compressor shaft to verify no mechanical lock?Check all wire connections for the compressor motor, a loose connection will cause a voltage drop due to arcing and will spike current cause a trip.

Rannzilla wrote:Hello All,My Coleman Mach A/C failed the other day. The fan works but when you turn on the A/C it immediately trips the circuit breaker. After pulling the cover I noticed the wire and connectors on top of the hard start was burnt. I replaced the hard start and the compressor relay with stock parts from my local RV dealer. After installing the new parts, I turned on the A/C and it ran for about 3-4 seconds and then tripped the breaker. I reset the the breaker turned the fan on a nd then turned the A/C on and the breaker tripped immediately just like it was wasw before. Any suggestions what my problems could be? The A/C unit is only 5 years old and was working fine up to this point.OK, on most OEM colemans there is NO soft start cap. One way to check is to count the caps. Two means no soft start. One is a run cap for the fan, one a run cap for the compressor. Three then you have a start cap. If you only had two, it could be that the run cap was bad, and would give symptoms like you describe. But replacing a start cap for a run cap would then give the symptoms you again noticed. the start cap has a thermistor cut out so it was acting as a run cap for a few seconds, then tripped out as it should. Then no run cap and the breaker tripped.

What breaker is tripping - inside the rig or shore power?

The circuit breaker inside the trailer.

It has three capacitors. I will try replacing the run capacitor. I can't get to the camper until next Wednesday. Did I destroyed the new start capacitor? Do I need to replace it again? Thanks for your imput in advance. I will give the results next Thursday. Thanks again.

A/C Tripping circuit breaker | Good Sam Community

11 Replies

RoyB
Explorer II
Jun 01, 2013
X2 on checking the 120VAC line voltage inside the trailer. You are describing what happens with low AC voltage.

If this is at a home shore power connection your 120VAC from the house may be too low to use.

In both my trailers connected to my garage 120VAC 15A and 20A receptacles I have one of these RV 120VAC VOLTMETERs plugged into a receptacle in the trailer close to the Air Conditioner controls. I always just glance over at the plugged-in 120VAC Voltmeter before turning the unit on. This voltmeter has the safe zone printed in GREEN.

just my thoughts
Roy Ken
thib2722
Explorer
Jun 01, 2013
Replace the breaker. Once they get hot and trip, they trip very easily. It's a cheap fix. About $10-13 for a new one. I had similar issue on my unit. The breakers, sadly, are cheaply made and fail easily.
Chuck_Gail
Explorer
May 31, 2013
I would check the voltage inside the RV when the A/C tried to run. A momentary dip is ok, but then it should return to AT LEAST 110 VAC. If it doesn't, maybe your shore power is no good.
time2roll
Nomad
May 31, 2013
After you replace the caps...

I would replace the breaker and check voltage.
Then probably a new air conditioner :(
Bob_Landry
Explorer
May 31, 2013
Altern wrote:
boogie_4wheel wrote:
Can you spin the compressor shaft to verify no mechanical lock?
:h And where would one find a 'compressor shaft' ?

It's a hermetically sealed compressor. I think that was one of those "I want to post something" posts.
Altern
Explorer
May 31, 2013
boogie_4wheel wrote:
Can you spin the compressor shaft to verify no mechanical lock?
:h And where would one find a 'compressor shaft' ?
Rannzilla
Explorer
May 31, 2013
It has three capacitors. I will try replacing the run capacitor. I can't get to the camper until next Wednesday. Did I destroyed the new start capacitor? Do I need to replace it again? Thanks for your imput in advance. I will give the results next Thursday. Thanks again.
Rannzilla
Explorer
May 31, 2013
The circuit breaker inside the trailer.
ksg5000
Explorer
May 31, 2013
What breaker is tripping - inside the rig or shore power?
ktmrfs
Explorer II
May 31, 2013
Rannzilla wrote:
Hello All,
My Coleman Mach A/C failed the other day. The fan works but when you turn on the A/C it immediately trips the circuit breaker. After pulling the cover I noticed the wire and connectors on top of the hard start was burnt. I replaced the hard start and the compressor relay with stock parts from my local RV dealer. After installing the new parts, I turned on the A/C and it ran for about 3-4 seconds and then tripped the breaker. I reset the the breaker turned the fan on a nd then turned the A/C on and the breaker tripped immediately just like it was wasw before. Any suggestions what my problems could be? The A/C unit is only 5 years old and was working fine up to this point.

OK, on most OEM colemans there is NO soft start cap. One way to check is to count the caps. Two means no soft start. One is a run cap for the fan, one a run cap for the compressor. Three then you have a start cap. If you only had two, it could be that the run cap was bad, and would give symptoms like you describe. But replacing a start cap for a run cap would then give the symptoms you again noticed. the start cap has a thermistor cut out so it was acting as a run cap for a few seconds, then tripped out as it should. Then no run cap and the breaker tripped.