Overheating when A/C is on!

DLiT

New member
At highway speeds (55mph +) with the A/C on my 08 JK Sahara keeps overheating. Coolant temp normally runs at 206 degrees and then the fan will kick on in high speed bringing it back down to around 194. While driving faster than 55mph the coolant temp will keep rising however, going up to the 230’s if I don’t slow down and turn off the A/C. Pretty sure it will keep rising but obviously I’m not trying to find out so I always have to slow down and shut of the A/C. I can manage driving at 60-65 with the windows down and keep a comfortable coolant temp, but I’d like to solve this issue. Any suggestions??

2008 JK Sahara
3.8L
Dana 44’s w/ E Lockers
5:13 gears
37” Pro Comps
 

WJCO

Meme King
Check that thermostat isn't stuck. This can be done with an infrared laser.

Make sure fins on radiator and condenser aren't plugged with shit.
 

DLiT

New member
Got a replacement thermostat just to be safe, and the fins aren’t in too bad of shape. Just wondering why it only happens when I turn on the A/C, that’s what’s making me scratch my head


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wjtstudios

Hooked
Start by washing the heck out of the radiator. Even just let a hose run over it, moving it from place to place every couple of minutes. If you run your Jeep at all on the trail, I would guess that is part or all of your problem. Over time they just get caked in mud. Make sure you hit both sides.

If that’s does not help, you might try flushing the coolant and putting new in.


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DLiT

New member
Cleaned both sides without too much pressure to avoid damaging fins, and I did a coolant flush (both directions)


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WJCO

Meme King
Got a replacement thermostat just to be safe, and the fins aren’t in too bad of shape. Just wondering why it only happens when I turn on the A/C, that’s what’s making me scratch my head


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The condenser for the AC system gets extremely hot when the AC is on and this item sits in front of the radiator. So when the AC is on, this puts a huge load on the cooling system. It really sounds like you could have a bunch of debris built up in the condenser fins and airflow is restricted. I used .250 copper pipe with holes drilled in it and it hooks to my garden hose to make a water pressure wand to clean out spaces like that.
 
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