[stuartnh]

Acceleration earlier did matter but now the ac comes out of the defroster vents all of the time, no matter what. I removed the radio and center consol, checked for leaks and reseated the lines at the switch and at the vacuum motors I manually moved the vents at the motors with normal resistance. I followed the vacuum line as close to the firewall on the passenger’s side as I could (the blower motor prevents seeing the last few inches). I then checked the vacuum line at the motor for blockage & leaks, I see no blockage or leaks.
An article I found on-line mentioned it could be a bad canister check valve. I went to a Ford dealer today and they said they never sold any nor did any dealers close by us have any of these valves. The dealer did give me the part number though! Any ideas would be appreciated.