How great of an impact does the A/C have on performance? Reason I ask is because yesterday after work and today to work, I had the A/C on and the car seemed somewhat sluggish and I found myself having to rev higher to have smooth shifts. If I kept the revs lower like I usually do (2-2.5K when I shift), the revs would drop down too quickly between shifts.

What's the deal here? Is it the A/C or something else? My car is absolutely stock to the bone, so any mod problems are out of the question.

EDIT: Forgot to mention that the A/C was working at half-capacity (2 bars on the fan indicator), and the outside temp was 72F and the auto climate was set to 70F.

 

any a/c compressor puts a HEAVY toll on the engine....expect this...especially on a day with high relative humidity..

 

ya a/c sucks quite a bit out of the engine. however, get an UDP and the power loss is noticably decreased but yet the a/c still works wonderfully. very interesting

 

Yes it hurts preformance and lower rpm shifts are harder and sometimes jerky. My car is modded, with most of whats out there, and it isn't so bad. A UDP helps a lot here.

Also it makes no difference what speed the fan is set to. If the compressor is engaged it's engaged and fan speed just chages the air speed through the coil.