A/C on generator question

[DelawareRick]

I'm new to the forum and, well, fairly new to the RV world but hope someone can help me understand something. (And I've done a good bit of research via Google, but still haven't found a straight answer that I could understand. That's why I'm posting here.)

First, my rig:
2006 Thor Hurricane 33H
Onan RV Marquis Gold 5500 generator w/about 1000 hours on it
Two 13,500 BTU air conditioners


My questions:
1. Should I be able to run both air conditioners simultaneously using my generator?
2. When I try to run both ACs on generator, the 20 amp breaker on the generator trips. I guess my question is, why not the 30 amp breaker on the generator? (I would think the ACs would/should be connected to the generator via the "bigger" breaker, but maybe I'm just completely backwards in that thinking.)
3. If the generator has nothing drawing power (because its breaker has tripped) would it shut down "on purpose"? Mine did yesterday, about 15 minutes after the AC tripped the breaker. I'm trying to determine if this indicates a problem, a fluke, or is "working as intended".

Thanks in advance for your help.

Rick

[joebedford]

You didn't say if your rig is 30A or 50A?? or did I miss it.

My rig is 50A and one AC is on one leg and the other is on the other leg. On shore power, 50A to each leg of course. On generator: 20A (or is it 25?) to one leg and 30A to the other. Basically enough to run the AC on the 20A but not much of anything else. I believe my converter is on the 30A leg with the other AC.

[dougrainer]

Slides do NOT require 120 power/ Your Test is exactly what I stated is the problem. Your 30 and 20 amp breakers are wired backwards. The EASIEST way to fix this is---Most Motorhomes run the 120 wires from the Onan to a 4x4 or 6x6 metal junction box within a few feet of the Onan. Open the cover and you will see the 2 Black and the 2 white 120 wires as well as the ground wires. Just reverse the 2 black wires and your problem is fixed. Doug

[Kayteg1]

Sounds like somebody messed up the wiring on the coach and with generator having 2 separate circuits it is easy to get confused.
That would require higher skills than DIY.
I would suggest taking it to RV specialist.
If you want to to play with it, you will need to open electrical box, identify the wires and than we can help you makes sense out of that.

[DelawareRick]

I just checked again regarding the tank level indicators. That doesn't work when either generator CB is tripped. Works fine if both breakers are on, works fine on shore power, works fine on battery.

[CA_Traveler]

Coach lights and monitor panel are 12V and run off of the battery and AC should not be a factor. Lack of 12V needs to be fixed first.

[DelawareRick]

Thanks for the replies so far everyone - they've certainly helped me understand this better. Or at least I think so.

dahkota - Water heater is off.

dclark - Neither AC runs if EITHER generator CB is off (see my troubleshooting steps below)

dougrainer - Your info was particularly useful. I did some troubleshooting and found the following:

With only 20 amp generator CB off:
Both AC units have no power
All outlets have NO power
No coach lights
Slide does work

With only 30 amp generator CB off:
Both AC units have no power
All outlets have power
No coach lights
Slide does work

Possibly unrelated: When one of the generator CBs is off (I forget which one) the "levels" button works and shows me tank, propane, etc levels. When the other CB is off, it doesn't. I only mention it because I wondered if power is being turned off to the thermostat (since it's in the same overall control panel) and that could be causing a problem. Again... new guy here... so might be completely off course.

[CA_Traveler]

Running 2 A/Cs on 30A is marginal unless they are smaller A/Cs. Typically this is where the 5500 shines as it should have one A/C on 30A and the second A/C on the 20A CB. Check to see it there are any other loads on the 20A CB.

There are a variety of reasons for the tripping CB. Dirt on areas inside and outside, weak CB, hard start capacitor failed or not installed, A/C problems and gen problems.

Rigs with this gen can be set up to run only one A/C at a time when on 30A shore power, ie they may automatically switch A/Cs but only one will run at a time.

[dougrainer]

OK, On your type set up.
The 30 amp on the Onan supplies the complete RV EXCEPT the Rear AC
The Rear AC should be connected to the 20 amp direct. Also may be connected thru a Front rear switch, but still direct to the 20 amp Onan
That is how 5500 Onans are wired on all Motorhomes.
I suspect your 30 and 20 amp wires are reversed at the Genset. Not an uncommon problem, especially if any work had been done on the system.
Start the Genset, turn the 30 amp breaker on the Onan OFF. If you get power to the rest of the RV your breakers are reversed. Doug

[dclark1946]

Twenty Amps is certainly not enough to run two 13.5 k BTU A/C units. It appears your RV is configured to run only one A/C at a time. You should have enough generator power to run both but not through the 20A breaker. Are you certain neither A/C will run with the 20A breaker off?

[dahkota]

We can run both A/Cs on our generator.
If we trip breakers, the first thing we check is if the water heater is on electric.
On 30A shore power, one A/C and the water heater will trip a breaker.
On generator, two A/Cs and the water heater will trip the breaker.
We also have a 5500 and two 13,500 a/cs.

Ours doesn't shut itself off without a load, only a fault. Check the blinking light and refer to the manual.

Best of luck solving your problem.