I was stopped in a drive thru running the ac when the temp gauge went almost to yellow 250° i shut off ac and ran heater only. It quickly dropped back to around 210° andran fine on the highway with ac on. However when i stop the temp goes up again. The radiator and thermostat are about 8 months old. Any thoughts?

 

sounds like you electric fan is not coming on. you should hear it turn on with the a/c while stopped and around 210 degrees.

 

I havnt taken a good look. Im at work now but it looks like there are 2 fans one higher than the other. Which fan would i look for?

 

Looked at it, only one fan and it is running. Small amount of coolant on top of resevoir. Would a leak cause overheat? This is not a sealed system like an xj right?

 

Only the one fan driven by a belt on a ZJ. Check the belt tension and I would be willing to bet the fan clutch is shot. The ZJ cooling system is not like the old pre 1991 XJ cooling system, but leaks are still a bad thing to have.

 

Any way to check fan clutch before i tear into it?

 

ah, thought there was still an electric. yeah probably clutch. The coolant on the top of the reservoir could be excess being pushed out from getting so hot, especially if it was filled near the top.

 

Thanks for the help guys!! Changed fan clutch and is running great. Nice and cool...