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glockshooter

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I have a question for some of you and hopefully you all can help me.  My wife and I have a 2013 Keystone Fusion Toy Hauler with a Cummins Onan 5500 generator on it and we had an interesting thing happen this morning.  We were just getting up for the day and the AC was running and had been all night long off and on as needed. All of the sudden the AC kicked on and the Generator stalls out and dies.  We had a trouble code pop up of 13 which means low voltage when you do the code check and I don't know why all the sudden it would do that if it worked fine all night.  I turned off the breaker to the AC and even changed the fuse even though i figured that wasn't it and still no luck.  When you turn off the breaker and turn off the AC at the control on the wall the generator runs fine and powers all things in the RV including the lights, microwave, TV, and refrigerator all at the same time but as soon as you flip the breaker for the AC and it tries to kick on BAM generator dead.  It has a brand new carburetor on it that i bought brand new six months ago and installed myself, for the sake of trying all things I even changed the oil and filer today thinking maybe it was overheating or something.  I am at a loss the only thing I can think of is maybe I am running low on coolant in the unit and it faults out and causes the generator to die.  other than that I have no idea.  Please  help if you can. 
 
Possibly the air conditioner is causing the problem.

It would be interesting to see if the air conditioner runs OK when plugged into shore power.

 
Arch Hoagland said:
Possibly the air conditioner is causing the problem.

It would be interesting to see if the air conditioner runs OK when plugged into shore power.
Click to expand...

Ya, I agree.

Something I learned being in extreme conditions multiple times. Don't turn off the generator, AC or heat even if it's not needed at that moment. Many things run fine that are broken but once turned off cannot be turned back on.
 
Two or three thoughts..

First there are forgotten loads in an RV. most common is the converter. Since lighting and some other stuff run on 12 volts you forget where the 12 volts comes from 120 volts and thus the generator.

Air Conditioners, when the condenser gunks up from things like.. Well Cotton wood trees did it to me last time I was where I am now... The current demands go up on the A/C.. HOWEVER not till it has run for a few minutes.


And finally.. Something serious. ranging from a bad start cap (around 10000 cents) not causing one of the motors to rotate to a siezed shaft on one of the motors (there are two, Blower/fan and Compressor). Areound (1,000 bucks)
 
When you changed the carb, is it possible that you goofed up the governor?  Can you watch the throttle to see if it goes wide open as a heavy load is turned on?
 
Try switching the refrigerator to gas operation.  In Auto or electric mode it can use anywhere from 400 to 800 watts, depending on the size of the refrigerator and this might be enough of an additional load to trip the low voltage cutout on the generator when it's hit with the AC's starting surge.  The refrigerator doesn't use enough propane to worry about, somewhere around 0.1 to 0.2 gallons every 24 hours.

It's likely the refrigerator was off (not calling for cooling) much of the night and then turned on when you got up and opened the door.
 
Given that the a/c ran fine all night, I think we can rule out that the genset governor was mucked up during the carb replacement 6 months previously.

An a/c has a huge start-up surge (high amp draw) as the compressor engages and this extra load seems to be driving the genset voltage down far enough to force shutdown.  This could mean the a/c surge has gotten worse, either because the start capacitor has failed or the compressor is having unusual difficulty (frozen up, failing compressor, etc.). Trying it on shore power is one good diagnostic, but shore power probably does not have the same built-in low voltage check that the genset has.  The a/c may start, even though it struggles a bit.  Watching a voltmeter would provide more info.


...and even changed the fuse even though i figured that wasn't it and still no luck.
Click to expand...

Not sure what fuse, you changed, but, for future reference, there are no fuses in the 120v power to the a/c unit.  Or for 120v power from the genset either.
 
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