Hey guys. Just found this site yesterday and see a lot of good info here. I hope someone can help me before I tear the dash out of this thing. I have a 94 GM new to me about 4 months. Retired my other 94 GM with over 250,000 and using it for parts on this car and my 95 GM. My problem is with the air flow through the heater plenum. I've done a lot of reading on this site and others over the last several days. I have manual slide controls. My air flow is through the vents only. Looking down into the plenum through the vent to the right of the temp. control, I can see the blend door operating properly as heat and cold is not an issue. I can see the actuator with the blue vac line operate when you change to vent and floor or defrost. I see that this door allows air to the floor and defrost ducts. My problem is that air blows through the vents all the time therefore not forcing enough air flow to the floor or defroster ducts. Where is the door located that closes off the dash vents? What actuates it and where is this actuator located? Should I be able to see this door close by looking down into the plenum through the vent? I changed the heater core in my now retired other GM but not looking forward to having to pull the dash out again. Any help would be greatly appreciated.