the selector that lets you determine which vent the air will blow through seems to be malfunctioning in my car. either that, or something related. switching between the first couple selections doesn't make much difference, air blows out of top and floor vents, even in the a/c recirculation mode and top-only mode. i figure this is either some sort of vacuum problem, or the flap that i usually hear moving when i change the selection is stuck.

does anyone have tips on troubleshooting either of these problems?

where is the flap that closes to allow air to recirculate or flow to the bottom vents?

if it's a vaccum leak, where should i start looking for the vacuum lines related to hvac?

this also might be related - when i'm accelerating with the a/c on, somewhere around the middle of 2nd gear the a/c seems to kick off for a few seconds until i've reached a constant speed. the fan still blows, but the the air is noticeably warmer for a few seconds.

thanks j-body.

oh, the car is a 2000 z-24

Sounds like what happened to my car after I took out the dash and put it back in. Vacuum needed to build up again. Check for a leak in your HVAC vaccuum lines...