Onan 4k Generator shuts down when the A/C compressor Cycles on

[dogmeat]

the initial inrush current is the same as the locked rotor current. once the rotor turns, it generates counter emf and thats what starts limiting the current. the true startup current is the difference between locked rotor and normal run current over the time it takes for that transition. prolly not much help but i'm in lockdown

[pconroy]

I missed the year - but someone posted that the newer Coleman 15Ks are coming with a soft start already installed.


Still - put me down as very curious to see how this resolves!

[Taylor O.]

the latest and greatest information is that, it may be the circuit board, they have ordered one in, due to be in on friday. The service advisor stated If this doesn't fix it, then its the fuel pump. Cummings is not 100% sure what the problem is, but they have already prepared an estimate for circuit board replacement of 851.46 plus diagnostic fee of $175.00. But that may not be the problem.
To add to this insult, now they are telling me, the generator will not run when you put any load on the generator?????? The generator ran fine and supported everything else on the toy hauler with the exception of the A/C 45 minutes prior to dropping it off to Cummings. I seriously have concerns at this point.

[Camper_bob]

Originally Posted by Taylor O.

the latest and greatest information is that, it may be the circuit board, they have ordered one in, due to be in on friday. The service advisor stated If this doesn't fix it, then its the fuel pump. Cummings is not 100% sure what the problem is, but they have already prepared an estimate for circuit board replacement of 851.46 plus diagnostic fee of $175.00. But that may not be the problem.
To add to this insult, now they are telling me, the generator will not run when you put any load on the generator?????? The generator ran fine and supported everything else on the toy hauler with the exception of the A/C 45 minutes prior to dropping it off to Cummings. I seriously have concerns at this point.

I would have serious concerns if I were you as well.

Fuel Pump is WAY cheaper than control board replacement. BTW, control board replacement should run around $450 for a good aftermarket one (check out Flight Systems out of Pennsylvania for an aftermarket board), and labor takes about 10 minutes to change it out.

If I thought it was the fuel pump OR the board, you can bet I'd be replacing that pump first.

[2edgesword]

Originally Posted by Taylor O.

the latest and greatest information is that, it may be the circuit board, they have ordered one in, due to be in on friday. The service advisor stated If this doesn't fix it, then its the fuel pump. Cummings is not 100% sure what the problem is, but they have already prepared an estimate for circuit board replacement of 851.46 plus diagnostic fee of $175.00. But that may not be the problem.
To add to this insult, now they are telling me, the generator will not run when you put any load on the generator?????? The generator ran fine and supported everything else on the toy hauler with the exception of the A/C 45 minutes prior to dropping it off to Cummings. I seriously have concerns at this point.

Very sorry to hear this especially given you mentioned the generator was able to run everything but the A/C. I wasn't clear if you were able to run multiple higher current items (microwave, coffee maker, electric water heater, etc.) all at the same time and the generator kept running. The "generator will nor run when you put any load on it" is troubling.

Unfortunately while recommending the Microair Easy Start wasn't an inexpensive solution ($300), and there was no guarantee installing it would have solved the problem, in hindsight it might have been worth a try. Even if it didn't solve the problem it would have provided the long term benefit of reducing the generator load and stress on the A/C motor. But that's hindsight. Now let's hope it's simply a PC board issue and not a fuel pump.

[Camper_bob]

Originally Posted by 2edgesword

Very sorry to hear this especially given you mentioned the generator was able to run everything but the A/C. I wasn't clear if you were able to run multiple higher current items (microwave, coffee maker, electric water heater, etc.) all at the same time and the generator kept running. The "generator will nor run when you put any load on it" is troubling.

Unfortunately while recommending the Microair Easy Start wasn't an inexpensive solution ($300), and there was no guarantee installing it would have solved the problem, in hindsight it might have been worth a try. Even if it didn't solve the problem it would have provided the long term benefit of reducing the generator load and stress on the A/C motor. But that's hindsight. Now let's hope it's simply a PC board issue and not a fuel pump.

Fuel pump is less than $100, and less than an hour labor. Control board will be at least $500 just for the board (they are not repairable) plus an hour labor.

So, ya, I'd be hoping for fuel pump. But more than that, I'd be hoping for a more accurate diagnosis instead of just throwing parts at it.

[Taylor O.]

Originally Posted by Camper_bob

Fuel pump is less than $100, and less than an hour labor. Control board will be at least $500 just for the board (they are not repairable) plus an hour labor.

So, ya, I'd be hoping for fuel pump. But more than that, I'd be hoping for a more accurate diagnosis instead of just throwing parts at it.

The Service Advisor is less than communicative. I have no faith in their abilities and not to mention, at this point, what they want to charge is 1/3 of the price of a NEW generator.

[Taylor O.]

Originally Posted by 2edgesword

Very sorry to hear this especially given you mentioned the generator was able to run everything but the A/C. I wasn't clear if you were able to run multiple higher current items (microwave, coffee maker, electric water heater, etc.) all at the same time and the generator kept running. The "generator will nor run when you put any load on it" is troubling.

Unfortunately while recommending the Microair Easy Start wasn't an inexpensive solution ($300), and there was no guarantee installing it would have solved the problem, in hindsight it might have been worth a try. Even if it didn't solve the problem it would have provided the long term benefit of reducing the generator load and stress on the A/C motor. But that's hindsight. Now let's hope it's simply a PC board issue and not a fuel pump.

The System will run everything flawlessly, except the A/C. The microwave, coffee maker, electric water heater, Water pump, Blow Dryer, Lights, exhaust fan, you name it. All except the A/C

[2edgesword]

Originally Posted by Camper_bob

Fuel pump is less than $100, and less than an hour labor. Control board will be at least $500 just for the board (they are not repairable) plus an hour labor.

So, ya, I'd be hoping for fuel pump. But more than that, I'd be hoping for a more accurate diagnosis instead of just throwing parts at it.

Unfortunately their (Cummins) plan of action is to replace the control board first and if that doesn't work change the fuel pump.

"it may be the circuit board, they have ordered one in, due to be in on friday. The service advisor stated If this doesn't fix it, then its the fuel pump."

[dogmeat]

wow thats a terrible way to troubleshoot. did it ever throw a fault code?

[Camper_bob]

Originally Posted by dogmeat

wow thats a terrible way to troubleshoot. did it ever throw a fault code?

+1

Unfortunately, I'm finding more and more that people are not "technicians" so much as they are parts changers.

Once in a while they're even right, but then, even a broken clock is right twice a day.

That's why I tend to bring my rig to the same shop I've been using for a couple years. Even though they've had some "slip-ups", they will troubleshoot and diagnose the issue properly rather than just throw a part at it and see what happens.

[Taylor O.]

just to keep everyone updated, I have not forgotten to post. Cummings has yet to get the part for over a week. I have no further information to pass along as of yet.

[2edgesword]

Thanks Taylor O.

[Taylor O.]

Good Afternoon Everyone. Thanks to all for the input on making this repair. I just wanted everyone to know, that the issue finally came down to the circuit board on the generator. Evidently, a spot on the circuit board that controlled the A/C system had shorted. Final repair cost was about $430.00 and unknown amount of man hours and some favors. But Big Bertha is up and running and going out this weekend. Again, Thanks everyone for their input and assistance

[Camper_bob]

Originally Posted by Taylor O.

Good Afternoon Everyone. Thanks to all for the input on making this repair. I just wanted everyone to know, that the issue finally came down to the circuit board on the generator. Evidently, a spot on the circuit board that controlled the A/C system had shorted. Final repair cost was about $430.00 and unknown amount of man hours and some favors. But Big Bertha is up and running and going out this weekend. Again, Thanks everyone for their input and assistance

I'm confused.

Are you saying that part of the generator's circuit board has some control over the air conditioning unit? That would be interesting to learn about...

[Taylor O.]

Originally Posted by Camper_bob

I'm confused.

Are you saying that part of the generator's circuit board has some control over the air conditioning unit? That would be interesting to learn about...

Yes Sir, the replacement circuit board fixed the problem. I can see off the old circuit board, there was a melted part of the circuit board that apparently created the problem

[2edgesword]

Originally Posted by Taylor O.

Good Afternoon Everyone. Thanks to all for the input on making this repair. I just wanted everyone to know, that the issue finally came down to the circuit board on the generator. Evidently, a spot on the circuit board that controlled the A/C system had shorted. Final repair cost was about $430.00 and unknown amount of man hours and some favors. But Big Bertha is up and running and going out this weekend. Again, Thanks everyone for their input and assistance

Glad to hear everything is back in operation. It is interesting to this one circuit on the board responsible for the operation of the A/C unit was at fault. That still leaves open the question of why everything worked off the generator prior to Onan get it and nothing worked after onan started diagnosing the issue.it's a circuit isolated to the A/C

[Taylor O.]

Originally Posted by 2edgesword

Glad to hear everything is back in operation. It is interesting to this one circuit on the board responsible for the operation of the A/C unit was at fault. That still leaves open the question of why everything worked off the generator prior to Onan get it and nothing worked after onan started diagnosing the issue.it's a circuit isolated to the A/C

I plugged the old circuit board in and it worked fine with the exception of the original a/c concern. Just proved to me not to use them in the future. Installed the new board and EVERYTHING powered just fine. It was just the one circuit that caused the problem.

[Gonzo54]

If this happens try shutting everything down and waiting about 5 minutes to restart gennie. After gennie starts wait about 5 more minutes to turn on AC. This allows all overload failsafes to reset. This always works for me! I’ve found that waiting about 5 minutes to turn on AC after initial starting of generator usually prevents this from happening. Also make sure of course that no other high amp draw appliances are on when starting. Hope this helps!