AC is stuck on defrost and floor which is default. What needs to be done to get the air blowing thru vents?

George Shapleton

Asked by George Apr 12, 2013 at 03:48 PM about the 2009 Mercury Grand Marquis

Question type: Maintenance & Repair

3 Answers


I found a similar problem in our database. It seems like the Ford products have a module that can fail. GM products use vacuum tube which fail. You can't win sometimes.


It most likely has a vacuum leak. Only a few times have i seen the control head go bad. you need to take the control head out and see if you have vacuum to it. and if not track down the broken hose

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Tom Demyan

The guys are right, a vacuum hose has popped off or cracked.

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