Generator quits when using both ACs.

[RRTSCB]

Hi,
I’m in an older RV (1999 Gulfstream Class A Scenic Cruiser). I have a dual A/C roof mounted system with Duo-Therm by Dometic branding.

Dry camping or driving running off my generator everything works fine for about 10-13 minutes with both units cooling nicely. Suddenly the generator shuts down and with it, both A/C units (naturally). I can leave off for 10 minutes or so then restart the gen. All works well again for about 10-13 minutes before gen again shuts down.

If I’m hooked up to 50 Amps service, no problems.

Anyone able to assist? Please PM me.

Thanks

[CHICKDOE]

what generator? what size a/c's? is any other electric load on (converter, water heater, etc)? do they shut down when running or when a compressor tries to start?

i do not know how your generator responds if it is overloaded? perhaps it shuts down.

[Bama Rambler]

How much fuel is in the fuel tank? I know on a lot of units, the low level cutoff for the generator is above the 1/4th tank level.

If you run the generator without running the A/C's does it run longer?

[Daycruiser]

My take is fuel starvation at the Gen with a heavy load. Fuel pump on the Gen may have retired and it's not getting enough fuel when you really load it up to keep running. The fact that it restarts tells me the fuel gets replenished when it shuts down. Just my 3 cents worth.

[NMWildcat]

Originally Posted by Daycruiser

My take is fuel starvation at the Gen with a heavy load. Fuel pump on the Gen may have retired and it's not getting enough fuel when you really load it up to keep running. The fact that it restarts tells me the fuel gets replenished when it shuts down. Just my 3 cents worth.

X2, first guess is fuel problem. Check/change fuel filter first.

[ActionJackson]

My guess is that your 2 20 year old a/c units are drawing more power than your generator can continually provide.

[wcrafter]

My best guess is the Gen to small for 2 AC's

[5picker]

Originally Posted by ActionJackson

My guess is that your 2 20 year old a/c units are drawing more power than your generator can continually provide.

Originally Posted by wcrafter

My best guess is the Gen to small for 2 AC's

I'm not going to say their two A/Cs aren't drawing too much current... BUT... that would make the generator shut down. It might trip the breaker but it wouldn't stop the engine.

Again, it sounds more like a fuel starvation issue under heavy load.

What happens if you only run one A/C? How long does it run?

[MtBiker]

Might be oil level. Some generators will shut down when the oil gets to low. With a full load and hot weather the oil may be foaming up after a bit and then tripping the low oil sensor.

[ActionJackson]

Originally Posted by 5picker

I'm not going to say their two A/Cs aren't drawing too much current... BUT... that would make the generator shut down. It might trip the breaker but it wouldn't stop the engine.

Again, it sounds more like a fuel starvation issue under heavy load.

What happens if you only run one A/C? How long does it run?

Maybe my circuit breaker is not working correctly on my generator, but if I overload my Micro 4000 Onan, it will totally shut down. Relieve the load off of it and it starts right back up.

Good advice to the OP to just run one and see what happens. If no more issues, it would be a power overdraw scenario.

[Daycruiser]

Originally Posted by Daycruiser

My take is fuel starvation at the Gen with a heavy load. Fuel pump on the Gen may have retired and it's not getting enough fuel when you really load it up to keep running. The fact that it restarts tells me the fuel gets replenished when it shuts down. Just my 3 cents worth.

Here's what led me to fuel starvation: "Dry camping or driving running off my generator everything works fine for about 10-13 minutes with both units cooling nicely." If it were a overload condition I strongly doubt it would run both for 13 minutes. Startup inrush is the highest load on the Gen, Once the compressors are up and running the load drops considerably. Just my second 3 cents.

[ppine]

Try running one AC unit at a time.

[dcheatwood]

Also, as in my recent experience. The gen can shut down if oil is too high. I had the shut down issue after first oil change and found a video on YouTube about it. Seems a little to much oil will cause shutdown as it warms up. After cool down, gen runs fine again for a little while.

The solution was to remove a little oil. I did that and the problem was gone. Seems more likely when gen is not level. Mine is an onan microquiet 4000.

Originally Posted by MtBiker

Might be oil level. Some generators will shut down when the oil gets to low. With a full load and hot weather the oil may be foaming up after a bit and then tripping the low oil sensor.

[5picker]

Originally Posted by dcheatwood

Also, as in my recent experience. The gen can shut down if oil is too high. I had the shut down issue after first oil change and found a video on YouTube about it. Seems a little to much oil will cause shutdown as it warms up. After cool down, gen runs fine again for a little while.

The solution was to remove a little oil. I did that and the problem was gone. Seems more likely when gen is not level. Mine is an onan microquiet 4000.

Interesting. Thanks for the post.

[RRTSCB]

For those who’ve asked, the fuel is propane and yes it’s full. In fact, it wasn’t until I refilled it that this problem started. Coincidence? Seems unlikely.

The only things running are the two roof-mounted A/C units; nothing else except those times when the Cummins diesel is running.

The generator is a GENERAC NP-66G.

DOMETIC DOU-THERM A/C units.

Thanks

[RRTSCB]

The oil in the generator is just below the FULL mark; it’s probably 9/10 full. Not overfilled and not too low. Thanks for that info; someone said I should drain out some of the oil but the level hasn’t changed in the last 4 months that I’ve been checking it and this issue has just started (over 4th of July weekend trip) and continues every time I’ve tested it.

[Daycruiser]

Originally Posted by RRTSCB

fuel is propane and yes it’s full.

Ok now there's an important piece of information. LP. Would have been nice to know that in the beginning. I want my 6 cents back.

[RRTSCB]

Sorry about that. ��

[CHICKDOE]

i looked at the manual for this generator. i could only find two reasons for a shutdown. one is low oil pressure and the other is over temperature. i did not find any indication that it flashes an error code like the onans do. so your guess. i could make a case for over temperature as it restarts and runs after it cools down. but that is purely a guess.

[RRTSCB]

Thank you!