The air will not blow out of my dash vents...defrost and floor only. I have had this same problem twice on a 2008 Grand Marquis, and the repair shop said it was the blend door and charged me about $600 each time to fix it. I was talking to a friend today who said that the blend door does not change the direction of the air, only the temperature of the air. Whoa...if that's true, I have wasted a lot of money. I did the self test and got an 888. So, I'm wondering where to start my search under the hood of a 2010 Grand Marquis. From what I have read on this site, I need to be looking for vacuum related things. I opened the hood to check it out, but don't know where to start. Your thoughts would be appreciated.

 

Here's a great test procedure I used to troubleshoot. http://www.sparkys-answers.com/2012/...-will-not.html

This led me to install new o-rings on the EATC

 

There's 4 #007 (9/32's) O rings needing to be replaced. Mine were dry and edgy and resulted in your symptoms. Pull the trim panel off carefully, being aware of the air bag light on the pass side, unclip it. The panel should hang low enough (with ash tray closed) to allow room to work. The head (EATC) unit comes out with 4 bolts. 8mm, I believe, and slide it out, like a stereo. 3 sets of wire connectors, pop them out, then the vacuum manifold, pull it STRAIGHT off, don't break the plastic nipples!

Now the unit is out you remove the 2 #15 torx screws to remove the inspection cover. Then the fun begins...It's quite simple, cuz I did it in less than an hour. And WOW am I happy I did! If you can tolerate this guy's ramblings, he has a great tutorial on this procedure. Here's the video link
621d534a4b7ffe248c2c054c1862fa7090ec4615
My Orings were outrageous, .89Cents each!! See the video on youtube!

 

or here... short version >

 

Location under the hood 07 Marquis a/c vaccum lines