My 02 SuperCrew Lariat (5.4L) is overheating whenever the air conditioning is running and the vehicle is just sitting. If the air conditioning is off, the vehicle can sit forever and not overheat or if I'm traveling and have the A/C on, it won't overheat.

I've flushed out the entire cooling system and replaced the water pump.

What am I missing?

Thanks!
Chris

 

Fan clutch is probably marginal, won't be to much longer before it gives out completely. The truck runs OK with AC on at highway speeds, doesnt it? Ram air cools the radiator then, at idle, the fan is supposed to increase speed and increase the air flow. Its not, normal engine running is OK but with the added temperature of the condensor it gets hotter. Oh, by the way, welcome to the forum.