Hello E60 experts. Whenever I use my AC ( snowflake button) my idle jumps to 700-750, plus it has an unusual sound. My best description of the sound is its like a leaf blower but not as loud of course. I would like to know what is causing my idle to jump up and stop the engine from sounding like a leaf blower.

 

Is this a trick question? How long have you owned the car? Are you toying with us?

- Idle jumps to compensate for the compressor load
- Leaf blower sound is A/C cooling fan

 

^ +1

When you turn on AC, it puts load on engine and as a result slight increase in RPM is expected. If the noise is more than usual AC compressor noise, you [or your mechanic] need to drop the drive belt and spin the AC compressor pulley by hand and hear for any unusual noise.

Or leaves are stuck in the fan and making that leaf blower noise :-)

 

Perhaps I'm extra paranoid because it just reached 100k miles. I was worried it might be signs of a bad thermostat or water pump. My other cars that I've owned didn't make such a noticeable sound. Even my lady had asked is there something wrong with the car.
Thanks for the reassurance fellas and pardon me being a " noob"