Since I design air conditioners, heat pumps and furnaces for a living, I'll chime in:


As Intreped175 said, the compressor will cycle more often, but the parasitic losses from the compressor will not change. As xviper said, you will also be drawing more current from the blower, which will load up the alternator more. The other factor that determines the amount of power required to turn the compressor is ambient temperature. The hotter it is the more power it takes to turn the compressor (the pressures are higher).

[QUOTE=Amit,Jun 19 2006, 07:52 AM]
2.

 

Interesting subject. No one yet has mentioned a very common convertible situation. Running with top down and running the AC wide open with full fan setting. That's what I do when running top down on a hot day. Screw the MPG.