weird noise when AC is on.

i started getting this strange noise coming from my engine compartment when the ac is on and during acceleration "around 1500-2000 rpm's". it does not do it when the AC is off. another thing. i switched the settings from outside air to recirculating the inside air, and its louder when i have it on recirculating. it almost sounds like a spitting sound. has anyone ever heard of this before?

Have you checked to see if it was coming from your compressor? Have someone in the truck, turn the a/c, rev it up some and see if you can hear where the noise is coming from.

It is probably your AC compressor acting normal. Especially when my truck hasnt been running long, the compressor will make a blowing noise at RPMs you mention. When the truck is at operating temperature, it will be less apparent. And when the AC is off and the truck is at operating temperature, I won't hear it at all.

It is annoying, I'll give you that. I'd rather listen to the sweet sound of the Flowmaster than that ugly whine coming from beneath the hood.

Hey I have the same problem except my truck will have an annoying squeeky noise. Does it have anything to do with the AC compressor belt? Mine looks like it needs to be changed. How about the AC compressor clutch(pulley thingy)? I hate to replace it all!

I said this in another post....I have the same problem in my 03 yukon. I've talked to people on the gm-trucks forum. From what other people say, it sounds like it's something to do with the ac director ( not sure what it's actually called) . Something in the gears that move it.. Mine sounds like morse code or something. I think it's probably something i'll live with. I'm not sure if it's something you can fix, unless you just replace the part I'll probably just live with it... :\ turn the music up... But my 40series does the trick pretty well