Volvo: volvo Air conditioner, ac system, ac compressor

Question
I have a 96 850 turbo wagon.  When i turn my heater on, it only blows hot air out of the left side of the drivers side.  COld air comes out the rest of the vents.  After driving a LONG while, some heat comes out of the other vents.  WHen i turn the AC on and use either the heater or AC, there is a sound coming from where the timing belt is.  SOmething turns on and off. It also revs my car a bit.  So basically, my car warms/cools left to right in a matter of hours.  THe motor is definetly where the timing belt is.  I see it spin and stop.  THe timing belt runs around it.  (this is when the AC is switched ON) whats wrong with my VOLVO!!   thanx

Answer
It sounds like you might have a broken valve inside the ducking of your dash where the air is routed to the multiple vents.  Sometimes, if one of those valves that directs air isn't working, you'll only get the desired flow from some of the vents.  But based on your question there are a few other thoughts.  First off, don't use the heater and have the AC on at the same time, do one or the other.  Second, when the AC is on, what you described the engine doing is comletely normal.  That isn't the timing belt, but the drive belt for the various devices, including the AC compressor, which turns off and on as you saw to maintain pressure in the AC system (thats what keep it cold).  At any rate, it is normal to click on and off, and for your engine to flinch a little bit when that happens.