What could cause the A/C to trip the breaker after it's been running for a while? Sometimes it trips it's own 20amp and sometimes it'll trip it's 20amp along with the main 30amp. It'll only do it when it's hot outside and the unit is really having to work. I've cleaned the coils throughly and they're spotless as well as the return air filter. The unit is 14 years old and I'm just wondering if age and wear will cause the A/C to draw more amps? I've had nothing else in the RV running and it doesn't matter if I'm on generator or shore power it will still trip. When it's cooler or at night it will run just fine.2000 Fleewood Expedition 36t with 30 amp service.

I would bet a compressor getting tired and nearing a lock stage. I would check the amperage draw on the compressor/unit as a starting point. A weak breaker could also cause this but if the main trips as well I would most likely rule that out.

Low voltage could increase amperage draw, hot ambient temps, age etc. could affect the breakers. If you could use an amp meter to check the draw, you might get a better idea whats going on.

It may be freezing up which makes the compressor harder to start when it cycles. High humidity may cause the freezing. You may try raising the temp on the thermostat, this can help to prevent the freezing up.Breakers do wear out and will trip easier.

Check the capacitors to see if they're physically leaking or the seals have blown.

Also, check the line voltage at any outlet in u'r rig. If its less than 108 VAC motor windings, AC compressor, can draw increased current, overheat and in time, fail.

A/C Tripping breaker | Good Sam Community

ScottG
Nomad
Jul 22, 2015
OP, check the tops of the cap(s) - they're about the size of a roll of half dollars or quarters. If they appear to be popped loose or any material is coming out of them, they are bad.
It costs nothing to do and is a cheap fix.

Here's what the failed cap in my AC looked like. Notice how the base looks canted and corroded (sorry for the blurry pic).
dougrainer
Nomad
Jul 22, 2015
ScottG wrote:
dougrainer wrote:
Capacitors START the motor and the compressor. They are not needed/used once the compressor is running. IF the system is tripping the 30 amp also, that points to a defective compressor. The compressor starts and slowly the amp draw rises until it goes over 20 amps. You need to check the amp draw of the compressor as it is running, and monitor for 30 minutes. IF it is over 15 amps, it is defective. Doug

Correct - they help start the motor. They are not being used after that but they are always in the circuit so if one were to short while the AC is running, it will stop everything.
The cap is not removed from the circuit once the motor starts, it just isn't necessary any more. It has to stay in the circuit to be charged again.

Possible, BUT, I have been repairing RV AC units for 36 years and have NEVER seen such a problem. Doug
ScottG
Nomad
Jul 21, 2015
dougrainer wrote:
Capacitors START the motor and the compressor. They are not needed/used once the compressor is running. IF the system is tripping the 30 amp also, that points to a defective compressor. The compressor starts and slowly the amp draw rises until it goes over 20 amps. You need to check the amp draw of the compressor as it is running, and monitor for 30 minutes. IF it is over 15 amps, it is defective. Doug

Correct - they help start the motor. They are not being used after that but they are always in the circuit so if one were to short while the AC is running, it will stop everything.
The cap is not removed from the circuit once the motor starts, it just isn't necessary any more. It has to stay in the circuit to be charged again.
Old-Biscuit
Explorer III
Jul 21, 2015
Happens on shore power AND on generator so rule out low voltage issues (unless generator has voltage issues)

A/C compressor!

But what the heck...you got 14 yrs out of it.
enblethen
Nomad
Jul 21, 2015
Could be low voltage.
Could be loose connection in the 120 volt AC distribution panel. Disconnect power and check for loose connections paying special attention to the neutrals(white wires) in the back of the panel.
dougrainer
Nomad
Jul 21, 2015
Capacitors START the motor and the compressor. They are not needed/used once the compressor is running. IF the system is tripping the 30 amp also, that points to a defective compressor. The compressor starts and slowly the amp draw rises until it goes over 20 amps. You need to check the amp draw of the compressor as it is running, and monitor for 30 minutes. IF it is over 15 amps, it is defective. Doug
ScottG
Nomad
Jul 21, 2015
Ivylog wrote:
At a minimum we need to know the voltage before it trips out while RUNNING... which means it's not a start capacitor problem. If you have another 20A breaker I'd swap them out. With high use breakers do loose some of their amp rating.
If the voltage while running gets below 108V the amps go up and that could be the reason the breaker is popping BUT it does it on generator so the voltage should be above 108.:h

A leaky cap may get worse as it warms up - I've seen this many times repairing electronics. The cap is always in the circuit being charged so just because it doesn't trip the breaker on start up doesn't mean it isn't the cause of the eventual overload. Caps don't always just fail all at once. They can function even while slowly dying.
Griffin_sride
Explorer
Jul 21, 2015
I'll put a meter on the line when I get home and check the amp draw once it's running and let you guys know. BTW weak breaker was my thought too and I've already replaced the 20amp and 30amp. But the fact that it occasionally trips the main 30 tells me the draw is real. Just confused at to why????
Ivylog
Explorer III
Jul 21, 2015
At a minimum we need to know the voltage before it trips out while RUNNING... which means it's not a start capacitor problem. If you have another 20A breaker I'd swap them out. With high use breakers do loose some of their amp rating.
If the voltage while running gets below 108V the amps go up and that could be the reason the breaker is popping BUT it does it on generator so the voltage should be above 108.:h
jolooote
Explorer
Jul 21, 2015
Also, check the line voltage at any outlet in u'r rig. If its less than 108 VAC motor windings, AC compressor, can draw increased current, overheat and in time, fail.

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