I am working on a 1990 Jaguar XJS Convertible. The problem has to do with ducting warmed air to the middle//upper tier of the system. I cannot get any warm air to either the center side vents or the defroster vents at the top of the dash. This while the lower vents in the knee area are blowing heated air strongly.
The air speed also seems anemic at the side vents although stronger at the top vents (defrost) than the sides. The temperature selected is the highest (when the temp knob is all the way clockwise) and the knee vents are blowing accordingly, but I am getting A/C cold from side and defroster outlets.

 

taperguy,

I've moved your question from General Tech Help to XJS forum. Members here with the same model will be able to help.

Graham