My mom took our 2002 Chevy Trailblazer LT into the shop to diagnose a problem we've been having with our truck for a while. The problem is generally this: the truck shows the "reduced power" and "service engine soon" light when we are driving and we put on the A.C. It guzzles gas like no other and makes a rattling sound when accelerating. The shop said it was a fan clutch problem and are asking for $900 to fix it. Is this a rip off? Is the fan clutch the actual problem? Thanks for any info given!