I have an 01 Ford Focus SE with a manual transmission. The car overheats while idling, still gets hot even when AC is on, but the AC blows cold, so Im assuming the AC fan is working. I've checked the fuses. It seems to cool down when the RPM's are up, so when idling, I have to rev the engine (increasingly more every day) to keep it out of the red. The AC being on helps the temp a little bit, but still overheats when its on. Please help!!!

 

Does the engine cooling fan come on ?, you can check this by unplugging the ECU temp sender, whereupon the fans for engine cooling should come on permanently, but as the problem is worsening check the radiator is not blocked as well, when the ac is on the fan for it also blows through the main rad as it is behind the ac condensor at the front.
Welcome to PF by the way!!
tabetha

 

Sounds to me like the water pump is on its way out, could also be a blockage somewhere.

 

As above, sounds like pump or a blockage, have you tried flushing the system?

Martin