2003 Ford F-150 Q&A
2003 Ford F-150 Question: Why does a/c blow out of defrost?
You have a vacuum leak somewhere in the dash. Check all vacuum hoses under the dash to make sure they are connected. - DaveJHM
Go to this web site and following the instructions. Its simple and it fixes the problem. Cost very little. I did it and it did fix the same problem your having. http://www.fordf150.net/forums/viewtopic.php?t=72104 - Visitor
The under dash blower and under hood blower, run/blows air when AC is selected all speeds. When controller is slid to heat, the under dash blower stops, but under hood blower continues to run and ...