Overheating at Idle/parked, AC involved.....

[fairmanicmaeve]

Have a 2004 KJ with 71K miles. Problem began about a week ago and I'm clueless. Parked and left engine running while I ran a quick errand. Was out all of 2 minutes tops. Noticed on my return that the AC was not blowing cold at all. Putting it in gear and leaving the parking lot, the ac began to blow cold off and on, so hubs and I stopped to check it out. While sitting in a there for about 5 minutes, it pegged over to hot (in the red) and we actually had some of the coolant bubble out of the overflow.

Checked the AC system, liquid line/orifice tube, vaccuumed the system and replaced coolant/oil because it was ******* out with high pressure. Jeep runs GREAT with absolutely NO signs of overheating at normal operating speeds both town AND highway. The only thing it does not seem to like is idling with the AC on. The temp stays just before the line in the middle of the gauge unless I sit for a few and have the ac on. I have been turning it off when I stop at red lights and the temp has been good. Also the compressor is audibly cycling fairly quickly and the system is clean and fully charged.

Any ideas what might be causing my overheating problem????

 

[dominator]

Did a check engine light come on before , during or after. Plug in a code reader to see if you have a code pending?

 

[fairmanicmaeve]

Check engine came on last week, remained on for less than 10 miles and went off again. We had just filled up and thought that it was a loose gas cap. It did not come on during the overheating or after.

 

[JeepJeepster]

If its over heating at idle check the engine fan. If you do not have the towing pack then you only have an electric fan. Has the coolant or t-stat ever been replaced?

 

[fairmanicmaeve]

coolant has been replaced but t-stat has not. The fan appears to work/come on when hubs checked it, but that doesn't mean it's not coming on properly while I'm out and about.

 

[2003KJ]

X2 on the fan. Should be on every time the a/c compressor is on, and/or when the engine temp gets to a certain point of being too hot.

 

[offrovering]

fan or radiator would be a good start. take tstat off and boil it to test.

 

[JeepJeepster]

'most' of the time if its a bad radiator it will overheat all the time, not just at idle.

 

[2003KJ]

'most' of the time if its a bad radiator it will overheat all the time, not just at idle.

General rule of thumb: Overheating at idle, look at the fan as it's an air flow problem. Overheating while driving, look at the radiator and/or water pump as it's a flow problem. There are exceptions however...

My money is still on a fubard fan.

 

[offrovering]

agreed on that, I just wouldnt overlook any part of the cooling system, overheating is never good, regardless of idle or driving (blarg)

Hope it gets resolved.

 

[fairmanicmaeve]

It was the fan! Purchased a new one, was easy and quick to install and the overheating issues stopped. Thanks for all the advice guys!!