2005 Mercury Marquis

You are dealing with a vacuum leak in this case. The air direction is changed by vents actuated by vacuum. If there is a leak, what you described happens. What you need to do is check for leaks both under the dash and the hood. If the engine is running, you may get lucky and hear a hissing sound where the leak is.

Let me know if you find it, but I'm confident that is the problem.

Let me know what you find.

Joe

My husband could not find a leak...is there any way to get a diagram of where to look....could it be anything else? Dealership says it is probably the control panel for a cost of $900....I cannot afford that...

There are two systems. One is manual and the other automatic. Here are the schematics for them. THe first is the manual system.

Let me know if this helps. Joe

Thank you for your help with this problem...I cannot view the schematics that you sent...I do not know if it is because it is the internet, but all the letters are blurred.....I think we could figure it out if we could view this.....is there any other way that you could send it so we can print it out?

Thanks..........Colleen

If there is another way, I don't know how. I was told that when you receive it, save it as a picture file and then you can open it under paint and enlarge it. Have you tried that?