Whats the deal with this? If I'm sitting still, it goes up between the 3/4 mark and the red zone. Even when I'm not sitting still, the water still gets hotter than when the AC is off. Why does the temperature go up when the AC is on?

 

On most cars the AC condenser is located in front of the radiator. The air passing through it hits the radiator next. The warmer air may be whats raising the temperature. The fans are also programmed to come on with the AC but my temps have always still gone up with the AC on even when I had the stock PCM program and stock cooling system.

 

Shouldnt, the ac should trigger the fans

 

Your fan switch for the a/c to kick on the fans may be out or not working properly. Also a lower temp thermostat and fan switch to kick the fans on would not hurt.

 

I had to have my radiator boiled to clean out the lime build up in it. It fixed the problem.