I am new member. Just bought a 2001 ZR2 for my daughter. When I turn on the AC I hear an extremely loud noise. Cannot tell if it is coming from the dash or from the compressor. When I turn the blower switch just to the vents the noise goes away. Then when I turn the switch to defrost the noise comes back. I tried to look up a thread of something similar but could not locate any. Probably from my search criteria. Anyone have thoughts or direction.

 

Could be your fan. I know in my '94, the "low" setting makes the fan make a really annoying noise, but if I turn it up to Med. or Med Hi, it goes away. It's not bad enough to make me want to try to tear apart the dash and fix it though!