Generator and partial power

[roadstar99]

We had Generac generator in shop before last trip because it would not produce power. Mechanic just serviced it and put in new filter and oil, etc. It worked. We were gone for 1 month and used it twice when power at campground tripped our breaker on 20 amp inverter side. Then again at power post.. After second time, reported it and unplugged from shore power (because this had happened the last time at same site in campground) and used the generator to cook dinner. We heard a noise that sounded like a belt. We used it again at rest stop for air. When we got to storage lot, turned on generator to use air and it cranked right up but no power. We had mobile service come out next day to check it out who advertised generator repair. He listened and turned off the inverter and said we need a new inverter and generator. He also said our running lights would not work without inverter and that inverter did not work because generator not putting out power. Is that true? Inverter working now. Lights also work. Hand out for $75. And preached to us about not needing the masks we had on. Back to mechanic for generator noise and repair. He replaced pulley with one from Onan and belt that didn't exactly fit and he knew would not work. He also said the transfer switch screws were loose. Said he tightened them up. He is a good mechanic and we like him but won't take anything back to him that is just motorhome related. Generator powered outlets and appliances but not A/Cs.
When the transfer switch switches from shore power to generator, does it switch again to shore power or is it just at rest and only switch to generator power? We can't plug in to check shore power. Have a plug but this motorhome is longer than last one and can't get down the steep driveway. Even offered camper repair company money to let us plug in and check power to A/Cs. It was too late in the day he said. Looking for a way to get power from our plug up driveway but no solution yet.
Cannot afford $10k for new generator. Need someone to repair dash air and only go where power is available.
Can someone tell me how to check transfer switch, what to look for?
Anyone know where we can get Generac repaired in Georgia?
Know this is long. Not thinking well. Sorry. I checked AC power at outlet and meter read 74.6 v with generator running, no load. Know that is wrong.

[okcnewbie]

I think you're on the right track as far as checking the transfer switch.
If possible you need to see if you have proper AC coming out of the gen.
With Onan's AFAIK they won't stay on without pretty good AC. If it's the same with Generac than if your gen stays on than you may have good AC at the gen output.
I can't link to it (I'm at work) but Darren over at MY RV works has a video on transfer switch replacement that likely covers troubleshooting as well. He has a host of videos and is a great teacher IMO.

Good luck.


If you're outside and not in a really high risk category than I would tend to agree about not needing mask.

[AZDave]

You did not identify the year and model of your coach along with what inverter you have which would help. So with a Generac I will guess this is a gas coach and provide my input based on that.

First the inverter does not provide power to the running lights. Those are 12v chassis powered. The inverter will provide power to some 120v outlets in the coach at a minimum and perhaps most of them depending on how large an inverter is installed. The A/C is not powered by the inverter. so is plugs work and not A/C I think the inverter is probably OK.

The transfer switch for RV is usually a default to the generator. It has two positions, generator and shore power. When plugged into shore power the switch will activate and connect the coach to shore power. If the generator is running it may not switch over a generator is usually the default. The terminal screws can get loose with time and cause a high resistance which can cause problems. Check and see if the screws are tight and that there are no signs of arcing or burning. Be sure you are unplugged and the generator is not running. With the generator off plug into 120v even if only using a 15 amp adapter. If close to the transfer switch you should hear it click, there is usually a time delay so give it a couple minutes. No click possible bad transfer switch.

Check the generator output voltage at the generator or the transfer switch, which ever is easiest to reach. If the voltage is low the generator probably has a problem. I read of a guy who had a gas Generac and the governor was letting it run slow and he only had about 75v output.

Hopefully this gets you headed in the direction of you problem.

[roadstar99]

I apologize for not identifying our coach and parts. We have a 2004 Newmar Dutch Star, 40 feet. The Generator is a Generac Quiet Pact 75D and a Xantrex RV 2012 inverter.
Went to campground last night and inverter is working correctly. Generator starts and runs but no power still. Since we are on a storage lot we cannot hook up to power and without generator no AC in 90°heat.
Thanks to all of you. Will try to check voltage at generator when I find manual to find voltage out connection. Will try My RV.

[twinboat]

Automatic transfer switchs are either switched to nothing, or switched to shore power, at rest with no input voltage from anywhere.

If you plug in to shore power, its already connected or it connects as soon as you plug it in.

When you start the generator, the ATS senses 120 volts from the generator and runs a delay timer for 30 seconds and then switches to generator power, even if shore power is plugged in and working.

That's how they work. Default shore power, priority generator power.

Most generators will not run if not producing power. They shut down and blink out a code.

If your getting 75 volts, the generator may not be getting up to proper RPMs.

That can happen if the fuel filter is plugged up. Last time that was changed ?

[roadstar99]

Thank you, Twinboat. I understand it better now. So where at the generator do I check output? Or is checking at outlet sufficient? Had fuel filter and complete service in March this year. The
Generator wasn't putting out power. It was serviced and worked again. I think the shore power problems we had at campground might have contributed to this problem. We were at same campground, same campsite, in Feb and had same breaker tripping problem. Will call mechanic and see if he changed fuel filter again in March. When power tripped off in CG, it was always at suppertime. So turned off shore power and cranked gen to cook.
Will get schematic and manual of transfer switch. Thanks. Will let you know what happens.

[roadstar99]

Mechanic said transfer switch was loose and almost lost screw. He also said there was a trip switch that was soft and he replaced it. The gen trip switch is also soft. Anytime we are under hood, we accidentally trip it.

[twinboat]

There should be a junction box, between the generator wiring and the RV wiring, somewhere near the generator.

That would be the place to check voltage if you suspect the ATS, because it come before it.

[tomgrigsby]

You can plug into a regular extension cord 20A circuit and the ATS will engage and all 120VAC circuits will be available. However, 20A is not enough to run air conditioning, and the microwave won't run well either. If you pull the cover off the ATS, you can measure the voltage at the input legs of the ATS. Usually the ones on the right will be shore power - easy to tell because your shore power cable is attached to those lugs. Read power from the black to ground and red to ground. Each should read 120 Volts more or less. Start the generator and measure the generator input lugs on the 2nd ATS input, usually to the left of the shore power input. Again, black to ground (or neutral) and red to ground should each be 120 volts. If the generator voltage is low, the ATS may not actuate to connect the generator to coach. As others have noted, if you're plugged into shore power and start then generator, the ATS will switch over to the generator after about 30 seconds or so. You'll clearly hear the contactor engage for either shore or generator. Measure the output of the ATS. If power is good at the input lugs and not at the output, you have a bad ATS.

[SteveR]

This may be a stupid question but did you reset the breakers ON the genset? My previous coach was notorious for tripping the genset breakers.



Also, check your transfer switch connections for loose connections. These are usually only screwed connections so they do come lose with time and vibration. If you getset is running and your coach accepts 120Volt power from shore then the genset breakers may need to be cycled on and off a few times to see if that is the issue; otherwise you need a new mechanic.

[roadstar99]

Yes. Gen breaker was checked constantly as it is soft and easy to trip. Could just be bad and will add that to the list. Thank you for reminding me.

[05kstar]

I have a 2005 7500generac and had low voltage at my plugs as well.The problem was the tensioner had backed off causing reduced rpm ,due to the belt slipping.

[roadstar99]

That may well be the problem. Mechanic thought so but could not find right one and it is loose. A nice young man named Aaron on this site found one for me and will order it and start there. Thank for reinforcing our diagnosis.

[roadstar99]

Is there a way you could make this diagram larger so I could print it?