I have a 1996 chevy tahoe that the ac has started acting funny in. It is making a strange winning noise at certain rpms mostly sous 2000 or at shift points, does anyone know what this points too. Other than that it seems to be working fine.

 

Are you sure it is not the Alternator ? It will make that type of noise especially under load when AC is on.
David g.

 

Pretty sure but not positive, is there a way to tell? Can't seem to get it to replicate the noise unless I'm moving

 

This sounds strange but it has worked for a long time. Use a broom handle or similar, @ just over 1,000 rpm's, hold one end on the AC Compressor and the other end to your ear. Compare the noise you hear from the Alternator to the AC for the loudest. JMHO.
David g.

 

Awwww yes the stethoscope method I will try that, thanks.