With the help of the FAQ & BB search, I believe I've tracked down the ECC problem that causes the dash vents to go off when climbing a steep hill. Clamping off the yellow hose at the solenoid valve bank allows the system to maintain vacuum even when the supply is disconnected. This appears to be one side of the dual-acting servo. Also, depressing the recirc button (while still clamping the yellow hose) allows vacuum to bleed off when the supply is disconnected. So I assume this means there's a leak in the recirc servo. All the other settings seem to hold vacuum ok.
Does this all sound correct? I obviously was able to remove the under-dash trim from the passenger footwell to get to the valve bank, however I'm unable to remove the driver's side trim under the steering wheel and around the airbox. Can someone give me some information on how to do this without breaking any of the 11 year old plastic? Once I'm in there, it appears that I can access the dual-acting servo with the instructions from the FAQ and then proceed to slice and dice my way into the replacement. Where is the physical location of the recirc servo and is it practical to replace it? Thanks for your help.
Marlin