This has been going on for about almost a year now where when I switch my air (doesn't matter if its AC or just regular air) from anyposition to Vents (off -> vents, heater -> vents etc, it doesn't matter) i hear the sound the car should make of the air flow being redirected and then all of a sudden something in there is SLAMMED (like the air redirecting parts.. or whatever goes on back there i'm not familiar with it) as the air goes to vent mode. Anyoen know if this is just an old age thing where I can fix it quickely or something?
thanks again
mike diaz

Its pretty much normal when you switch your vents to hear noise coming out of the back sometimes the odd pop sound to , i think all the bonnevilles in this years do that noise right guys?

You mean like a POP, Pop, pop ? Mine did the same thing until I adjusted the link on the defrost/vent diverter servo. When vaccuum is off the servo moves to the defost position and if adjusted too log will wedge the valve in the a/c duct. The POP is when it comes loose - canwatch the servo bend everything as it tries to unstick the valve.

I just reached up in the dash (servo link is above the gas pedal and points up at about 60 degrees) with an ignition wrench - might have been 7 mm - loosened the adjustment in the middle of the rod, and shortened a bit. No more clatter.

mine used to do that too. also when i would go up a hill or when ever i was drawing hp from the engine like that for a long time, the vacuum would drop, and my vents would close up, but after i was over the hill, the vents would open back up, i assume cuz there was more vacuum to force them open. this problem went on for years and it turned out that there was a leak under the hood in the vacuum lines. i fixed that and it doesnt do that anymore, no more pops or loud noises when the vents change. check to see ifyou have any leaks in your lines.

I'm looking at my servo today and I see it move smoe and then finally break open the vents i guses as it does that POP, pop, pop, pop.... sound. How exactly did you adjust it? What'* an ignition wrench if you dont' mind me asking? how'd you shorten the adjustment... and what'* the adjustment ? I know i know its a lot of dumb questions but I'm a little confused on its parts. but rest assured i know where and what the servo is.
Thanks a bunch!
Mike Diaz

there is a two piece linkage about eight inches long that connects the servoactuater (vaccuum thingie) to the diverter valve. Just about in the middle of the link there is a machine screw that AFAIR takes a 7 mm wrench. Loosen the screw and the two pieces of the rod can slide to either shorten (what you want to do) or lengthen the rod.

An ignition wrench is a short (about 3" long) thin wrench in small sizes originally for adjusting distributers. Sears has a nice metric set #9-4308 that goes from 5 mm to 11 mm.

DONE!!!
Removed under dash panels (7mm bolts) then saw the servo, loosened its screw, shortened the length by as much as posslbe, retightened into new position, no more loud POPPOPpop!

Thanks again guys!
Mike Diaz