Jed has provided the information you need.
The whistling sound is probably a bearing on its way out. If you are not comfortable inspecting the accessory belt system, take it to a shop.
The extra noise may be your A/C compressor in an impending failure mode. There is an alternative explanation that will require you to open the hood and try to isolate the source of the noise. If the noise is coming from the throttle body are when the A/C compressor engages, you have an idle air control valve that is exhibiting symptoms of "moosing".
Jed,
One correction. Fans are wired in parallel and are two-speed. A/C always forces high speed operation.
You're right, I liked it better when I had to turn on the controls for what I wanted. I'm no dummy...
Steve
