Overheating when AC is on

seanb123

seanb123

New member
As the title states my jeep is over heating when the AC is on. It's a 2008 with the 3.8. Was about 100 yesterday when it first happened turned the ac on driving and not getting any real cold air from the ac until I was moving then noticed it was at 3/4 turned ac off rest of the drive and went down to normal. Tried Asian just before I got home and back to 3/4 and same thing this morning. Coolant level is good. Fan seams to be kicking in right. Any ideas on how to figure this out. I'm most likely going to do a thermostat and flush the coolant but wanted some opinions first
 
seanb123 said:
As the title states my jeep is over heating when the AC is on. It's a 2008 with the 3.8. Was about 100 yesterday when it first happened turned the ac on driving and not getting any real cold air from the ac until I was moving then noticed it was at 3/4 turned ac off rest of the drive and went down to normal. Tried Asian just before I got home and back to 3/4 and same thing this morning. Coolant level is good. Fan seams to be kicking in right. Any ideas on how to figure this out. I'm most likely going to do a thermostat and flush the coolant but wanted some opinions first
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If this is happening when climbing a hill, your AC being on will cause your temp to go up. If it's happening while driving on flat ground and you're sure your fan is kicking into the higher speed like it should, you might want to check to make sure you don't have air in the system and give your water pump and t-stat a look.
 
same as mentioned above, when was the last time you flushed your coolant? if it's never been done, you should flush it and change the thermostat while your at it.
you can buy an antifreeze tester for $3 or less but if you've never flushed it, no need to test.
 
I finally had some time to try and nab this problem and it's proving to be harder that I anticipated. Did the the thermostat no change. Flushed the coolant today and it was pretty nasty but still having this issue. One thing I did notice was that when it was over heating at times the fan would still be running on low and then turn the ac all the way up fan comes on and goes back to normal
 
The most overlooked item of the cooling system is the radiator cap. If the cap isn't holding pressure the boiling point will be lower. I replace mine every two years regardless of how it looks.
 
Mine was doing the same thing, i replaced the thermostat and changed the coolant, had no luck. Afterwards I pulled off the grill and all the plastic around the radiator and took a hose to it for about 15minutes. Usually I only pressure wash, but after really cleaning it my temp went to normal. Afterwards I went 80 on the interstate when it was about 110 out with the ac on full blast and it didn't even creep past halfway.
 
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