First of all, my knowledge of cars starts and stops with changing brakes and rotors so let me begin with that.

I'm getting a pulsating revving sound when in park. If the car sits for a bit (warming up for example) it will be continuous as I drive. Trying to recharge my A/C myself I noticed when I put the gauge on the valve the needle would spike up and down in the same sequence as the sound. I've been told my a/c compressor is still functioning correctly. My heat works but my a/c won't blow cold. Guess I can take it to Nissan to get looked at but I was hoping someone has been down this road and knew the reason for this off hand. I'm driving an '08 Maxima SE. Bought it used and as far as I know no custom set up...everything should be stock.