AC - does the AC have a heater or is it engine heat that's used?

[LegoHead]

I would like to know because I can either have AC on or off. Does having it on switch a heater on to heat up the car quicker? Or does it just use engine heat?

 

[fUbAr]

As far as i know there is a heater, hence why you can have it blowing hot air when the engine is cold.

 

[LegoHead]

cool, thanks. It takes a while to warm the car up on auto, will try the ac button tomorrow.