For anyone that is using the MegaSquirt for closed loop idle control and still wants to use their air conditioning, there is hope. The latest Alpha code (pre3.3 Alpha5) has functionality to control the A/C compressor and open the IAC to premptively compensate for the load. This eliminates dips and flares in RPM, not to mention prevent embarassing stalls in traffic. I was so happy with the code that I put together a wiki article here: A/C Idle Up
There is also a bit on the adaptive idle advance code which is very nice as well. The Alpha code has been stable for my application, so I suggest you give it a shot rather than wait for these features to be put into full release code.
