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wmiii · 06-27-2022, 08:55 AM

We were driving down I-75 though Georgia and Florida this past weekend. I had the Gen set running to keep both our AC units running. When I stopped Saturday, I noticed that the rear AC unit had tripped the breaker. I reset it and all was good. Sunday, we stopped for fuel and I noticed that it had tripped the breaker again. Later on down the road, I noticed the Gen set had stopped. I saw the code 3-8 which means overload, I think. The only things on were the roof air units and the refrigerator.
Thoughts?

Thanks,
Wm Mayberry
2088 Tiffin Phaeton 40QSH
2011 Honda CRV

craigd853 · 06-27-2022, 09:25 AM

Quote:

Originally Posted by wmiii

We were driving down I-75 though Georgia and Florida this past weekend. I had the Gen set running to keep both our AC units running. When I stopped Saturday, I noticed that the rear AC unit had tripped the breaker. I reset it and all was good. Sunday, we stopped for fuel and I noticed that it had tripped the breaker again. Later on down the road, I noticed the Gen set had stopped. I saw the code 3-8 which means overload, I think. The only things on were the roof air units and the refrigerator.
Thoughts?

Thanks,
Wm Mayberry
2088 Tiffin Phaeton 40QSH
2011 Honda CRV

Hello, a couple of things to check for is to see if both a/c's are on the same circuit, I assume not because you said you reset the breaker and all was fine. The other thing to check is your run capacitors on the a/c and look for any burn't wiring which is a clear sign your a/c is pulling to many amps. If all looks good check wiring terminals on breaker to make sure they are tight and breaker is good. One other suggestion, if all the above checks out I would use a volt meter and see how many amps are being used on the a/c that is tripping the breaker versus the one that is running correctly. Check both at start up and running. This should give you a good idea if there is problem with the unit or not. Good luck

DRM901 · 06-27-2022, 09:37 AM

I suspect you have a bad start &/or run capacitor. Get a multimeter that tests for capacitance.

You can test for start up amps, but you will need something that tests for inrush.

https://www.amazon.com/KAIWEETS-Curr.../dp/B09YYK3PML

Sent from my SM-G973U using iRV2 - RV Forum mobile app

jacwjames · 06-27-2022, 02:46 PM

While you are checking the capacitors take the time to see how freely the motor spins by hand.

I was having trouble with my front one kicking the breaker every once in a while so I some testing while running the generator since I could look at the amp meter on the EMS system. At startup I saw really high amps for a little while until the motor was running. Went up on top and tried to turn the motor by hand and it was almost froze up. I had to replace it.

wmiii · 06-28-2022, 04:34 AM

Thanks for the ideas. It looks like I'll need to get someone who knows about the AC units to look at them and go from there.
Would I know any more by running the rear AC unit on shore power? If any of those issues are there, would they present themselves then?
Thanks,
Wm

wmiii · 06-29-2022, 04:28 AM

Interesting!
I went over to check on our coach and the forward AC unit had tripped the breaker. I'm connected to 30 Amp service , so only have front AC on.
Always something...
Wm

sibe · 06-29-2022, 04:54 AM

What size genset..

2 AC running ..

30Amp shore..

IMO you are boarderline overload. Even 2 13.5K AC units will pull 11.5-13 amps each depending on temps, age etc.. at compressor restart amp surge that can add 50% more load for a second or three.... Provided no parasitic draws like the converter/inverter, microwave/TV standby mode, refridge running on AC.. as these things can add 3-5 idle amps on system to start with.. SO even 4 amp base load.. 2 AC units pulling 24 amps.. you are at 28.. on a 30A system, sneeze and something gonna trip...

wmiii · 06-30-2022, 04:53 AM

Quote:

Originally Posted by sibe

What size genset..

2 AC running ..

30Amp shore..

IMO you are boarderline overload. Even 2 13.5K AC units will pull 11.5-13 amps each depending on temps, age etc.. at compressor restart amp surge that can add 50% more load for a second or three.... Provided no parasitic draws like the converter/inverter, microwave/TV standby mode, refridge running on AC.. as these things can add 3-5 idle amps on system to start with.. SO even 4 amp base load.. 2 AC units pulling 24 amps.. you are at 28.. on a 30A system, sneeze and something gonna trip...

I have a 8KW Gen set. That could possibly be the issue. It was hot coming down I-75 through Georgia and Florida this past weekend.
All seems to be working well now on shore power. I'm thinking my glitch earlier might have been due to lightning in the Tampa Bay area.
I'll just keep an eye on it.
Thanks all for the ideas.
Wm

jacwjames · 06-30-2022, 06:23 AM

I have a 7.5KW Onan and can easily run both AC's on the generator.

If you have an Intellitec EMS type system with the load meter you can do a health check on the AC's but you have to be hooked to a 30 amp circuit or running your generator so the amps show on the meter. (on a 50 amp circuit it won't display amps)

Turn on each AC separately and watch the load meter, as it starts you can see the amps spike, my fans by themselves pulls ~4-5 amp and then when the compressor kicks on goes to ~17-18 amps.

When I was having trouble with my breaker tripping on the front AC unit I started watching the load meter and saw very high amps at start up, once it started it pulled slightly higher amps. That's when I found the motor almost froze up, could barely turn it by hand so I replaced.

Xmcdog · 06-30-2022, 06:44 AM

All good suggestions above. Also try cleaning the condenser coils.
You said it was hot when it tripped. Hot weather and dirty coils will raise the head pressure so the compressor works harder and pulls more amps. Hope this helps.

NXR · 06-30-2022, 06:47 AM

When ours was new the front A/C breaker tripped multiple times during our 3-day PDI. The dealer tech told me that he would take the handle of a screwdriver and thump the breakers to see if one was mechanically bad. He thumped each breaker and only the one for the front A/C tripped. He replaced it and it's been fine for 3 years.

The Atwood thermostat showed an E4 error code when it happened, Low Refrigerant. But that was just erroneous due to the tripped breaker.

Also, if you can catch it right after it trips, does the breaker feel more than slightly warm?

They trip based on heat (current through a bimetal contact set) and if a breaker feels too warm it may have a high electrical resistance inside causing it to trip erroneously. I had that happen to a breaker at home. It measured at under a half-ohm of resistance, which is a lot when it should be a flat 0 ohms.

Ray