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Old 08-10-2011, 11:39 PM   #15
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Location: Dublin, VA
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Originally Posted by faulknerice View Post
I have a Generac 40 QP Gas generator on my 2007 class c It over heats when running the ac when the temperature is in the mid 90's

I have done the following
shut down all but ac
installed a hard start cap in ac
new spark
clean carb
syn oil
new air cleaner
adjusted valve lash
checked cooling fan

any one else have problems with generators overheating in 95+ temps with ac on
Sounds like you've covered many of the possible problems and I agree that perhaps all you've missed within your power is replacing the fuel filter and providing additional air to the generator. You may have a good generator but I must say that we had a Generac gas generator and it seemed to have a mind of its own. Then again, our Onan might prove to be the same.....who knows.

Mike & Cindy, (of course with Lucy the Miniature Schnauzer & Eddie the Yorkie) Dublin, VA / Fun Finder TT / X215WSK
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Old 08-11-2011, 07:02 AM   #16
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Location: Hawkeye State
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Morning All,
According to the Onan Service Center my issue was, most likely, caused by the frequency (60hz) adjustment being out of whack. According to the tech the half load frequency was 63 - 64 which would set the genset into alarm (shutting down) when the load changed - A/C cycling or even the 300w for the refrig. They ran the genset for approx 30 minutes and load tested. I ran the genset and A/C for the trip home (approx 40 minutes) - with no problem. Now the outside temp yesterday was no where near 95 so we'll have to wait and see..... Overall the shop was very professional and covered the adjustment under warranty - another plus. I have to wonder what kind of service/response I would have received at the dealer.....

2011 Jayco 31SS V10
2006 Ranger Reata 1850
2014 Jeep Grand Cherokee 4-down
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Old 08-11-2011, 08:32 AM   #17
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It sounds very touchy. I have an Onan 4000 and hope not to have the problems you have but from what I have seen in the past each RV has its own factory installed gremlin. Mine is in the radio which ships today from Jayco so Orlando RV can install it and then hopefully I can take it home after more than a month in service…
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Old 08-11-2011, 09:58 AM   #18
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My generator is also the 4000 Onan - just checked on a power management system. the particular one I checked alarms at + or - 9 hertz so yes very touchy. Good luck on the radio
2011 Jayco 31SS V10
2006 Ranger Reata 1850
2014 Jeep Grand Cherokee 4-down
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Old 08-11-2011, 07:21 PM   #19
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Location: Pensacola Area
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Smile Onan dealer says he found the problem.

Originally Posted by lowpasslew View Post
I contacted Amsoil headquarters and they thought it was OK to use their product unless the Onan handbook or spec sheet said no. Onan dealer said nothing was in writing, but they had seen a couple instances where synthetics were suspected in poor ring seating. That is like me taking my person experience instead of my periodontal specialist training in dentistry. They still have my RV. I'll keep you posted on the results. It seldom gets over 95 in Orlando, so I won't really know until I venture into superheated conditions again.

Dealer did a no charge inspection and repair under warranty. Dealer said some internal mechanism was completely loose and they tightened it. (Paperwork left in RV, now in storage for many months) The generator works fine now, but the test will be on the road under 100 degree stress.

good marks for the dealer..changed oil for $30. www.cumminspowersouth.com Orlando, FL
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Old 04-28-2015, 09:33 AM   #20
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my Genset ( onan emerald ) was over heating alot on summer days.
Here is how i fixed it.
I left the side covers on the heads to direct air flow........however.....
On the top of the gen set.....a metal black cover hides the intake and exhuast manifolds. It does not get air from the fan, and the hot exhuast is literally 1 inch from the intake manifold .
I removed this top cover....left it off ,and made a heat shield to go between the manifolds.....and now i can run the genset in mid summer with no issues.
I think the gas was getting flash boiled in the manifold.
We take our class A motor home to bowling green OH every year to the tractor pulls, and the gen runs 3 days non stop in summer. First 2 years it shut down with a wicked back fire after the first 4 hrs, but since I removed the top cover....it didnt die out at all.
Hope this helps alittle
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Old 04-30-2015, 09:58 AM   #21
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Onan 4KW Generator

I have the 4KW Onan in a '96 Dutchmen. It has run great except that it likes to develop a problem. It will not continue to run after being started. It acts as if the "kill" switch is shorting out. I contacted a shop in northern AL and was told that the Control board is probably the culprit--a $375 replacement!

After doing some investigation, I removed the Control board. Underneath the board is a set of ground wires connected to a multi-lug. One of the wires was disconnected. I reconnected the lug onto the ground. Replaced the Control board and the Generator has been running without incident.

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generator, heating

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