Overheats while sitting with A/C on, but not while driving???

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Jun 25, 2004
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VA
I have a 1996 L/C. I have searched but I couldn't find anyone with the same symptoms I was having. While driving last week (and it was HOT) I got stuck in traffic. Well, the rig started to overheat. I cut the A/C off and it went back down. So, I cut it on again, because it was so HOT and it went back up after awhile. Once the traffic cleared (driving) I had no overheating issues. What could it be?
 
Joined
Sep 12, 2010
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Yep. The tuned up blue hub solved that problem for me. The rest of the cooling system in my rig is about 2 years old, the fan was the only old part left.

Was going to 210-215 on the scanguage while lugging up a hill or sitting in traffic or pulling a small trailer, and I would turn the air off and turn the heat on for a minute if needed to keep it away from 220+. I since have not gotten out of the low 190's sitting stopped with the A/C on, close to 90F outside.
 
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Jan 10, 2010
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Happy Camp, California
Agreed the fan clutch needs to be dealt with.

I replaced mine with a Hayden which cost around $60. Been on a year and it works just fine.

My summers are spent chugging grandkids up logging roads in 90 plus temps (low humidity) and even with my dear wife in the truck and the air going full blast we do just fine.

Good luck.
 
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the west desert
If your clutch is an original type unit (Eaton or Aisin) and in usable condition, the best fix is to simply change the fluid. They are much more durable, powerful clutches than anything available aftermarket.

...listen to tools, he knows what he is talking about. Changing the clutch oil is a pretty easy procedure.
 
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x4 on the fan clutch. You might want to look into the fan clutch mod. https://forum.ih8mud.com/80-series-tech/102633-blue-fan-clutch-mod.html (in the FAQ)

That link shows how to do the temperature setting, and fluid change.

The fan clutch comes off of the water pump pulley with 4 nuts (which also hold the pulley on). Loosen the top of the fan shroud, take off the 4 nuts, and put a piece of cardboard between the radiator and fan when you pull the fan and clutch out.
 
Joined
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VA
So, simply just changing the clutch oil will fix my problem of overheating when sitting still with the A/C on? Wow! The rig is my daily driver.

I live in Eastern VA. So, what number of "cst" fluid will I need (7000, 8000, 10000, 15000)? Where can I get the cst fluid from? I want to buy locally, if possible.
 
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Joined
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maybe...I tried that on my old fan clutch, changed it twice, once to 10k fluid, then once to about 17k fluid, and it never performed the way the new blue hub did. At some point, the clutch itself gets worn out or the spring does not turn at the right temperature anymore, or something.

The fluid is cheap, and if it does not work, then you already know how to take the fan clutch off to put another one on!
 
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VA
ok. I know that I have to go to a hobby shop of some sort, but what number CST do I get for Eastern VA? I don't do any off-roading. It is a daily driver with some fun stuff at times.
 

retrofive

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ok. I know that I have to go to a hobby shop of some sort, but what number CST do I get for Eastern VA? I don't do any off-roading. It is a daily driver with some fun stuff at times.

I would start with 10k. I just bought a bottle of ONFA r/c diff fluid 10000cst for $9.95 at our local hobby store. Gal behind the counter thought I was nuts LOL.

Anyway just going through this I may have spare aisin black hub avail if you need it. Won't know for a few days tho.
 
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So, simply just changing the clutch oil will fix my problem of overheating when sitting still with the A/C on? Wow! The rig is my daily driver.

I live in Eastern VA. So, what number of "cst" fluid will I need (7000, 8000, 10000, 15000)? Where can I get the cst fluid from? I want to buy locally, if possible.

It can fix the problem, if the clutch is weak, a common issue, but cooling problems are difficult to "see" through the web!:hillbilly:

The best fluid varies depending on; type of clutch (there are 3 common types) and climate/use. The first step is to compare your clutch to posted pix to ID it or post a pic of it.

Once the clutch is off, the condition needs to be evaluated to be sure it is worth messing with, most are. It is easy, the bearing needs to turn smoothly, the thermostat spring is not excessively rusted and the valve turns smoothly, doesn't stick.
 

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