Air flow from vents while rolling but not when stopped.

[meekdog]

When I'm driving I get air flowing through the AC vents even if the heater or AC is switched off. The faster I go, the more air comes in. If I'm stopped no air comes in. If its hot ouside I get hot air. If its cold ouside the air seems to be a little warmer than the outside air. I'm sure its a flap or valve or something but I have no idea where to start without tearing everything apart to find the problem. PS, I also have constant vacuum to the tube which goes to the passenger side kick panel vent. I'm guessing thats not normal either. Thanks for any help you can give, Meekdog.

[JimKshortstep4x4]

I would suggest making sure the air door in the cowl is closed. There is a vacuum operator that closes the door and it may not be working. Check for vacuum at the operator.

Jim

[eightbanger]

I've been messing around for a while now with mine so here goes under the dash in the cab where all the heater box stuff is there is one part called the A/Conditioning upper lower diverter box its the one that the S-Plenum is attached to. In this box is a flap that controls whether your air is diverted to the windshield or the floor vent when you select it on the control panel, these fail and the flap stays open letting the air come through your A/C diverter balls and cener vent (this was my problem) I would say your diverter box is the prob as well. The passenger kick panel vent should have vacuum to it keeping it closed and when you select inside air the vent will open, also check the vent door under your cowl look through the slots on the cowl on the passenger side and see if it is open or closed this might have some bearing on your outside air prob. Have a look at5 this thread.
http://67-72chevytrucks.com/vboard/s...d.php?t=283860

There you go Jim helped me.