1998 Olds 88 a/c. Weird problem.

My gf`s 88 is doing something really weird. When you turn the a/c on,it immediately makes this vibrating/banging noise from the engine compartment somewhere. The engine will shake,try to sputter and die,and smoke starts coming from someplace. I tried to watch the engine and a/c compressor while she turned the a/c on and off with the engine running but I can`t tell where the problem is. Any ideas????? I`ve never had a car do this before so I don`t know where to begin.

Wanted to add........if it`s just idling it`s not as bad,but if you rev the motor,it gets REALLY bad and loud,like a knocking sound. But as soon as you turn off the a/c,the noise immediately stops. I`m guessing the clutch on the a/c compressor is going bad? Could that be where the smoke came from......the clutch causing resistance on the serpentine belt causing slippage?

This is hard to diagnose without seeing or hearing! It may be a blockage in the orifice screen causing excessive head pressure on the compressor, or the harmonic balancer outer ring separated from the inner ring. You need to get some expert on-site advice from a trusted mechanic.

The harmonic balancer..........I didn`t think of that. Makes sense though seeing as the ac still blows cold and it`s not shaking or vibrating when I`m watching it. I`ll check it out and see what happens.