A noisy problem recently reared it's ugly head. When my '07 LX is not warm (1st startup of the day), it goes into high idle mode (1500 rpm) for about 15 seconds then starts slowing down normally. However, if the AC is engaged, a noisy racket is present. I can shut off AC and it immediately goes away. AC blows very, very cold air regardless. When it's good and warm, no problems at startup whatsoever after that. What's the consensus here? Thanks.