hello, my Daughters 2008 fous has 65,000 miles on it and started having idle problems while running the a/c. what happens is the car ,when stopped at stoplights or sign, will idle rough or fluctuate from 900rpm down to 500rpm and jump back and forth.she took it into the dealer and for $99.00 they did a pcm update and said the car was fine. When she left and went down the road and stopped,the car still had the problem so they didn't fix anything. i called them and they said we could bring the car back and they'll check it again, of course with no new fee. This only does it while using the a/c, any ideas or experience with this? thanks Randy

 

Sounds like the IAC (Idle Air Controller) isn't working properly. It just might need a cleaning.

 

Valid point - I just wanna add that some IACs can not be cleaned and must be replaced. A misbehaving IAC though should misbehave at all times, and not only when A/C kicks in. Try this: put the car in neutral, take your foot off the gas and then put it in drive without stepping on the gas. If the RPMs bounce up and down, then the IAC is bad. If the idle stays while the car starts moving, the problem is elsewhere ... let us know what you find.

Good luck!