i have a2007 mercury grand marquis and when I drive the a/c blows out the defroster instead of the vents
2 Answers
if your selector switch is in the correct position for vent/dash divert and it blows out the windshield only then its a electrical diverter door or switch control that is not working, if it blows out the vent/dash but then switches to the windshield when your driving its a vacuum leak to one of your hoses under the dash which are extremely hard to locate not recommended for a novice, seek a mechanic for this preferably your Ford dealer.
FordMasterTech answered 12 years ago
The EATC module is at fault. These can be repaired or replaced on eBay pretty cheap. The guy who did mine was eatc-man on ebay. He has a store Ford EATC and more on eBay as well. He offers both repair and replacement. Here is the link http://stores.ebay.com/Ford-EATC-and-more.