[Richard]

I am going to dogpile on this one for hope that it will help someone in the future.

My dash air flow was abysmally low. I had too problems. One the fan motor was poorly grounded. The giveaway was that a jolt in the highway would result in a change in air flow. A big a Ha on that one. The fan ground was into a a flimsy piece of aluminum on the front wall. I ran a ground to the big ground post in the front passenger kick well.

The second and bigger problem was the air dampers themselves. I removed the air damper box and put it on the bench. I used one of the those hand vacuum generators available in at any car parts store. It was evident that the dampers were not sealing tight when activated due to two reasons. One the foam used to seal had long given up the ghost, and there were also some mechanical interferences that prevented them from fully closing. These damper boxes were custom jobs, and mine was probably less than optimum from the factory. I used the pump and fine tuned until they sealed off when activated.

It was a two day project but well worth the time. Like Steve said removing the dash and gaining access is not an easy job, but if you have the stuff out of the way, you might want to check the operartion of the damper box.