Both A/c's won't always run on generator especially when hot (when needed most!)

[Reyco50]

Hello! new to forum and itt seems others have had similar issues but wanted to know the latest on this issue if anyone knows. My dealer is having issues narrowing down the problem, I have a 2013 329 Georgetown with a Onan 5.5 and 2 Dometic A/C's.

Often, not always, when I try to turn on the 2nd A/C, the generator shuts off power to both. I have to then wait a few minutes, restart the a/c 's again. They may fail 1 out of 4 attempts. This problems never happens on shore power. The dealer seems to think it might be a heat factor on the a/c 's because he asked me when it happened more and I said when it's hot outside. Isn't that when you need an a/c i said! It rarely fails for them in their much cooler service bays. However, I'm asking them why couldn't this be a generator issue???

The R/V is only a year old and has approx 200 hours on generator, so it's fairly new. I'm asking if they can't run diagnostics or monitor the amperage draw on both generators and/or the a/c units. They appear to be hesitant because it doesn't fail often and they are not being paid for "diagnostic time". So, they are motivated to have it get worse(at my expense and frustration) before identifying issues because they are more likely to get paid for an identified failed component that is covered under warranty. It has failed in their presence although the mechanic appears to be skeptical. Any ideas would be appreciated.
Thanks jerry!

[bubbles]

Originally Posted by Reyco50

Hello! new to forum and itt seems others have had similar issues but wanted to know the latest on this issue if anyone knows. My dealer is having issues narrowing down the problem, I have a 2013 329 Georgetown with a Onan 5.5 and 2 Dometic A/C's.

Often, not always, when I try to turn on the 2nd A/C, the generator shuts off power to both. I have to then wait a few minutes, restart the a/c 's again. They may fail 1 out of 4 attempts. This problems never happens on shore power. The dealer seems to think it might be a heat factor on the a/c 's because he asked me when it happened more and I said when it's hot outside. Isn't that when you need an a/c i said! It rarely fails for them in their much cooler service bays. However, I'm asking them why couldn't this be a generator issue???

The R/V is only a year old and has approx 200 hours on generator, so it's fairly new. I'm asking if they can't run diagnostics or monitor the amperage draw on both generators and/or the a/c units. They appear to be hesitant because it doesn't fail often and they are not being paid for "diagnostic time". So, they are motivated to have it get worse(at my expense and frustration) before identifying issues because they are more likely to get paid for an identified failed component that is covered under warranty. It has failed in their presence although the mechanic appears to be skeptical. Any ideas would be appreciated.
Thanks jerry!

Well, a major difference between shore power and gen power is that shore power is 50 amps 2 phase (100 amps total) delivered to 2 load busses (50 amps to each bus). The gen delivers about 49 amps 1 phase (49 amps total) to those 2 busses. The A/C's typically are wired with 1 A/C on bus 1 and the other on bus 2. 5500 watts (gen output) is probably right on the edge of sufficient power in your situation (with everything else powered and both A/C's happen to start up together). JMO.

[fonzie]

When running the generator for the AC's, make sure your water heater is on propane only, fridge on propane if possible, reducing current consumption from other appliances might work......

[sithc]

I have the same issue on my 2015 351DS. I'm just guessing too much power needed from the generator. Mine happens when I drive and use the generator to power the fridge, tv, whatever else plugged in such as phone, etc. It would turn on for a bit and eventually trip the breaker on the generator. I learn to live with just using the back one and the fronts being cooled by the front cab A/C from the RV itself.

[dezolen]

That is why 7KW is offered as option which will run everything.

[rwehba]

Maybe fr should have installed the bigger one so no problems huh


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[wrapperman]

I have a 2013 378XL
5500 watt generator
Both a/c running and can still run the microwave. Even when it is very hot.
I'm not a certified mechanic but sounds like a generator inverter problem
Let us know if you find out


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[Cypressloser]

The key here is the power draw most aren't aware off and that is the battery charger.
Depending on generator type and setup (btw. the same applies to shore power) the power is either fed directly to the batteries and the AC's or fed through the RV's converter/charger and then shared. This draw can be as much as 15 Amp AC on larger chargers. One option is to let the batteries charge for a couple of hours before starting the AC that shares the circuit with the charger.

[Reyco50]

Originally Posted by bubbles

Well, a major difference between shore power and gen power is that shore power is 50 amps 2 phase (100 amps total) delivered to 2 load busses (50 amps to each bus). The gen delivers about 49 amps 1 phase (49 amps total) to those 2 busses. The A/C's typically are wired with 1 A/C on bus 1 and the other on bus 2. 5500 watts (gen output) is probably right on the edge of sufficient power in your situation (with everything else powered and both A/C's happen to start up together). JMO.

Thank you for yur response JMO. Yes, your absolutely correct based on what my Tech said also. However, it fails with only the 2 a/c's and nothing else on since I've been very careful not to overload. Pls let me know if you know of anything else that might need checking. thank you…jerry

[bubbles]

Originally Posted by Reyco50

Thank you for yur response JMO. Yes, your absolutely correct based on what my Tech said also. However, it fails with only the 2 a/c's and nothing else on since I've been very careful not to overload. Pls let me know if you know of anything else that might need checking. thank you…jerry

Since it does operate normally otherwise (Im assuming it is) all I can possibly think of is to let an authorized gen repair facility connect a load bank to the unit and check that the advertised output load is being produced. Could possibly be a 60Hz issue also because of speed controls. There are numerous adjustements the repair facility can make. It's kind of difficult to try and come up with just one reason for these gen issues, such as your's because it evidently functions just fine in all other scenarios. I'm sorry I could not be of further assistance to your questions. There are very knowledgeable individuals on this forum and maybe one will chime in. I have always had a 70kva gen and this issue has never happened to me. Good luck. JMO

[speedjester]

I have a 5500 gen.. And run two 13k AC units in Fl heat with out a problem.... I also run my microwave convection oven at the same time without issue... I will mention..when I went to pickup my unit during the PDI the gen trip the breaker when both units fired up... ( didn't happen when my inspector checked it).. They had a Cummings Gen specialist there ... He checked a few things.. Had dealer change the plug for the 50amp cord ( it was loose) where it plugged into the gen.. Then he replaced the board on the gen....it's been running everything without issue... Even making the newbie mistake of firing up generator with both AC on....

[DocGTO]

If you have 2-15k btu Ac units then forget it. Too much power draw. If 2-13,5k then it should work fine. I have the same genny and it will run everything and 1-15k btu Ac no problem.

[ChrisAndGarren]

We have 2 15 AC units and I run them on the genny no problem when driving. Have even used th microwave. 351Ds.

[Dijoeboss]

Been dealing with this very issue since Feb. 2013 on XL, no fix other than to consider a larger generator! Installed hard start capictors, no help, changed out transfer switch, no help, I've just learned to accept the fact that it would have been nice to have gotten the larger generator from the start!!


2013 Georgetown XL 350
Bunkhouse
2002 F250 4X4 CC
2012 Jeep Liberty

[wrapperman]

I don't understand why it doesn't provide enough power for everything on your coach.
My 5500 watt generator powers everything on my 378 xl. Including 2 heats strips (1500 watts each)( A/C's are 1500 watts each), fireplace heater (1500 watts refrigerator, microwave and all lights with no trouble.
If it is still under warranty take it to a certified Onan dealer and have them put it under a load test.
Let us know how things turn out.
Good luck



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[Trempert]

I run 2 A/C all the time and whatever else I want including the water heater (on electric) and never once have I blown a breaker. 3+ years.....something is wrong with the generator. I would start by checking the voltage output by starting the generator without load and checking the voltage at one of the outlets. I would say ideal is 115-120V with a preference of 120V. Then start the A/C's one by one and see if the voltage is maintained at the outlet. As voltage drops, more current is drawn and that will blow the breaker every time. I'm guessing the generator voltage is either set too low or is not being maintained with a load. One trick is to have the voltage set 2-3 volts higher than the specs. It won't hurt anything and will lower the current draw.

[Dijoeboss]

How do you set the voltage? I didn't know it was adjustable???

I have been fightin tryin to run 2 a/c's all day-- it ain't happenin!!!!

2013 Georgetown XL 350
Bunkhouse
2002 F250 4X4 CC
2012 Jeep Liberty

[Trempert]

Sorry, I now realize the voltage is electronically controlled at 120 volts. I don't think the Onan 5500 has an adjustment. Check the voltage as described earlier. It should stay right at 120v.


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[Maddog378]

My 2011 378 has the same 5500 onan. Runs everything at the same time with no problem. 2-13.5s in my unit. The only problem I have is that with both ac's on, traveling down the road, the transfer switch shuts off power to everything especially during drive over very rough roads.
Called Parallax and asked about the ATS 501 transfer switch in my unit, and the gentleman said that this switch was not designed for a moving vehicle such as a motorhome. For fixed installations it was fine, but extreme vibration would cause it to turn off power. If that is the case, G-town needs to look at another brand that is up to the task!
We are still extremely happy with our unit, and April Conner has helped get all the problems fixed. I only wish the overhead front drop down bed had been available when we bought our unit from Lazy Days.
Happy camping!

[sithc]

That could possibly be the case. As the only time I use the generator is when I'm driving.