I had the problem of the air coming out of my defrosters (whenever it wanted to)
I used the following link to help fix this problem:
I cut out both plugs and used three tees and normal vacuum lines instead of reusing the plugs
Hopefully this will help someone.
Don't call the dealer for a new one they are over $1000.00 dollors.
Used ones $75.00 and up
Change the vacuum lines and plugs $15.00