Generac Guardian idle control not working

Portable standby generator troubleshooting and repair questions. (Gasoline, diesel, propane, natural gas)
Bassguitarist1985
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Wed Jan 23, 2019 12:44 am

Have you checked the neutral lug and terminal block? One of the spade connectors, breakers, or outlets is bad. My vote is your stator windings are fine.
zooeyhall
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Sun Jan 27, 2019 7:53 pm

I have been doing some further testing on this generator.

I used an electric drill to test the 120v outlets.

On one outlet leg of the 120 volt, (with idle control on) placing a load moves the generator out of idle and runs it ok. This is a standard duplex outlet.

However, on the other 120 volt leg, applying a load will move the generator out of idle and will run the drill properly. It does this for about 8 - 10 seconds. Then the generator idles down, as if it isn't detecting a load. This outlet is a 120v GFCI.

Idle control off, and applying a load to both outlets, it runs the drill ok.

Could this be a problem with the CT transformer that monitors this one leg? Would a defective CT display this type of behavior?

It seems to me that a defective winding would just not work at all. The same with a bad connection or bad outlet. Or a defective CT.

Wondering what defect could explain the above behavior.

Thanks!
Chris
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Sun Jan 27, 2019 9:05 pm

That sounds more like the CT on that leg is going bad. You could always swap them and see what happens... If the problem shifts, you know the cause
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Bassguitarist1985
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Tue Feb 05, 2019 11:10 pm

The CT could be bad, the GFCI outlet itself could be bad, or any outlet. There is a spec for CT, and are wired in series. They can fail, but rarely. Your windings are fine, you got stupid lucky. If any damage was to occur from line power besides boards frying, the little windings would burn first in the few seconds, the mains would tolerate more heat. Worst case is the EMF from the generator trying to sync to the mains frequency out of phase from each other would have caused catastrophic damage, as in shafts snapping, explosions, and metal twisting

I've personally worked on this exact machine. The hot legs wires need to be right up against the winding. The smaller machines it only takes 1Amp of current to bring the engine from idle to full speed. The bigger machines like this one it can take 4-6 amps. Honestly the feature should not be turned on when connected to a transfer switch. 48hz 95vac is not good for any loads, especially motors.

All the outlets are jumpered off the 50A outlet. Make sure they all ohm out to zero (or close to) properly on the hot legs, neutral, and ground. The GFCI could have been damaged, and can easily be replaced as the hot jumper is left intact like in a house install.

Last thought, all the blue signal wires, those spade connectors can get loose, and never hurts to squirt electrical contact cleaner in connectors C1 and C2.

Cheers!


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Guardian ultrasource control panel
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zooeyhall
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Sun Feb 10, 2019 9:07 pm

Wanted to leave an update on this.

I was using a small 3/8 inch drill to test the idle control. It would speed up the generator when plugged into one leg, but wouldn't kick-in the full power when plugged into the second 120v leg.

However today I tried a 1500 watt heater in the 2nd leg, and that triggers the idle control just fine.

So apparently the second leg needed something that drew more power than the drill, to trigger the idle control.

Just want to know if this indicates the generator is working ok. I am curious why one leg of the generator needs a larger amp draw load to move it out of idle. Is this normal operation?
Bassguitarist1985
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Sun Feb 10, 2019 9:19 pm

Yes I would say your machine is working just fine.
zooeyhall
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Sun Feb 10, 2019 10:27 pm

Bassguitarist1985---just read your post. Thank you!

Unfortunately I didn't read your post until this evening. It would have saved me a lot of troubleshooting. Obviously, my little drill didn't pull enough, especially if as you say it can take 5-6 amps to trigger the idle control.

I guess it threw me that it worked on one leg, and not the other.

Also good advice on not using the idle control when connected to a house. It (the idle control) is probably meant more for use in such things as construction sites. Where tools are being turned on and off intermitently.
Bassguitarist1985
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Sun Feb 10, 2019 10:44 pm

Yessir. Its the sensitivity of the current transformers and the actual circuit itself on the board. What helps is to make sure the hot wires are as close to the CT coil as possible. Other than that you should be good!
zooeyhall
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Mon Feb 11, 2019 10:30 am

One more question--

The LED on the voltage controller (upper left-hand corner). Is that supposed to be on or off when operating?
Chris
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Mon Feb 11, 2019 10:40 am

That should be on when producing power. If it's off, the unit isn't producing power, but may still be running.
Generac tech for over 12 years. I'm here to help!
"The only source of knowledge is experience" -Albert Einstein
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