AC Kills Generator

Thanks for the replies. The extra loads are a possible issue. Would low compression cause this kind of problem?

I first noticed the problem when I had been running down the road for a couple of hours. My refrigerator would have been running and the converter is possible but not likely since the batteries are getting charged by my solar bank and the alternator from the engine. Still it is something to consider. They pulled the Gen set out of the RV to fix a leak between the halves of the case. The oil had leaked down under the generator and mixed with dirt and coated part of the generator. They originally assumed that the generator was overheating because of the oil and dirt caked on it. While they had it out they adjusted the valves. When I got it home I ran it and it started having problems after running for close to 2 hours.

4WheelWaterdog wrote:
Thanks for the reply.
There are 2 breakers on the generator. A 30 amp and a 20 amp. The 30 amp runs the first compressor in the AC and everything else in the motorhome. The 20 amp breaker runs the second compressor only. I have had the problem occur when nothing else is running but the AC. I don't have the unit here to check, but I think it has in the neighborhood of 1400 hours on it. It does not use an unusual amount of oil and I have not seen it smoke.

Do not overlook the converter is active when you run the generator. They draw generally 7 +/- amps. Depends partly on the state of charge of the batteries. I had the same problem as you and exhaustive testing by a factory electrical engineer determined to many amps were required for the generator output. The converter was a major contributor of the problem.

On another thread, an ONAN tech used the term "Load Acceptance" and that's what I was thinking here. I had to replace the carb on our little 4.0 KY genset. Before that, I could start the genset, start the A/C, set A/C so it never cycled (max cold) and the genset would carry that load till I shut it off. If I changed that load in any way (add or remove load) the genset would shut down and not start again till it cooled.
So I wonder, Did this Problem simply Develop, or was there Disuse that might have allowed a little Varnishing to occur in the Carburetor? On our KY it was probably the "idle" circuit in trouble with some varnishing. Counterintuitive, but the Idle Circuit plays a part in loaded operation. I don't know that there are carbs any more sensitive and finicky than on small gensets.
PackPack often mentions Carbon. Our old BFA was one of the ONAN engines with the Carbon Issue. I bought it used and not running, no idea of hours on it, and didn't know about the carbon issue. If I had, I probably would have cleaned it and installed new head gaskets before installing in the coach. Once in, no way was I going after heads when it was running OK. Our problem was a varnished carb (which I struggled with before having it professionally cleaned ultrasonically), AND a weakened Governor Spring.
I wish I had the experience to tell you if going after Carbon or Carburetor is your next best step.

Several things I would try. Clamp on meter for amp draw. Read up on setting carb close attn to idle setting make sure its not touching screw at idle. Clean carbon out of heads and from valves and set valves to spec. My gen is older than yours but once I had the throttle touching the idle stop screw and it wouldn't take a load right and it would bog it down.

double check for 'forgotten' loads
water heater, fridge, if the batteries are the converter can pull a large load

its a good idea to start the genset early, don't wait until its 100* inside the RV

get some charge on the batteries, run the A/C on 'FAN"

then after about an hr turn on the A/C, turn it on high, let things cool down real good before using set point
restarting the compressor's is what is overloading the genset

It is a HGJAB. I don't have the serial number since the coach is at the RV dealer. ONAN 983-0501 is the service manual for this model. I have a copy, also in the RV. The AC is one Basement unit with 2 compressors. Heat pump. http://www.rvcomfort.com/rvp/pdf_documents/1976252.pdf The idea is that it can run on a 30 amp service. The second compressor comes on after the first is done with the start up spike. I have had the unit for about 8 years. Never had a problem until just recently.

Can you get us a model and serial number from the gen so we can look for a service manual. When you say compressors do you mean two ac units. Is this gen new to you or have you had it awhile ? Did it ever run both acs without bogging down ?

Thanks for the reply.
There are 2 breakers on the generator. A 30 amp and a 20 amp. The 30 amp runs the first compressor in the AC and everything else in the motorhome. The 20 amp breaker runs the second compressor only. I have had the problem occur when nothing else is running but the AC. I don't have the unit here to check, but I think it has in the neighborhood of 1400 hours on it. It does not use an unusual amount of oil and I have not seen it smoke.

Sounds like its overloading. Are you running anything else when this happens? I believe there is two breakers on that gen it depends which breaker the ac is on and what's on that same breaker. How many hours are on the gen . It could need the valves set to spec and a little seafoam run through it.