hi, I'm new to the mercury forum, & hoping to find some help. A/c works good after driving down the road. Sitting still,or slow moving traffic, not so good. Dealer said it's a bad blend actuator door. Is there more than 1 ? How hard is is to replace ? , where might it be ? Dealer wanted $650.00 to replace it. Any help would be greatly appreciated. Starting to get mighty toasty in NC