GM-GMC: a/c dashboard access, vent option, dash vents

Question
my 1989 blazr will not blow air out the dash vents. How do I get at the routing system inside the dash? Is there a drawing somewhere?

Answer
Tom,

  You did not mention wehter-or-not it blows out all the other vents. I'm assuming it does. I would just do a quick check to make sure that you mode selector on the dash is working properly, if it does seem to be "selecting" the dash vent option it will probably turn out be be a ModeDoor in side you heater Box or a blockage somewhere along the way. You will need to remove the entire AirBox to examine the blend/mode doors and a repair manual like a chilton manual or equivalent would be a great help. This is a fairly big job, since alot of the dash will need to be removed to access. I also hear that a site called WWW.Alldata.com will for a one time fee supply tou with you entire vehicle manual on line that you can access as many times as you want. hope this helps!