I just bought the car, it's an 04 with 90K miles on it, 5 spd. When even I am at idle and I turn on the defroster or AC, the motor shakes. I only notice it at idle probably because there is too much going on while I'm actually driving down the road to notice it while the car is actually moving. Any ideas? I would think if it were the pulley/compressor wheel on the compressor then it would do it whether it was on or not. Thanks for the help.