i have a 99 zr2 and the heat works great but it wont go to the floor what would cause this
i looked behind the glove box and the and that seeems to be moving fine . what else could be the pro blem



thanks for the help guys

 

So when you change the modes (defrost, vent, etc..) it will go, but when you put it in the floor it doesn't work? If that is the case, then you may have a bad vacuum actuator for the floor blend door.

If it only comes out through the defrost, you most likely have a vacuum supply problem to the HVAC control head.

 

I noticed for my blazer that if I am going from the face vents (vents on the dash) to the floor it takes about 15-20 seconds for to fully change over.

 

My bet is the floor blend door is broken. The arm snaps off of the door itself. On a '99 Blazer, you can check this by removing the plastic panel that contains the 12V outlets and then sticking your head up into the dash over by the throttle pedal. If you look up in there (again on the driver's side) you can see a white arm sticking out of the HVAC module with a torsion spring on it. Then there's a rod going down to the vacuum actuator. If you start the truck up and turn the right side HVAC dial from vent to heat, you can see the vacuum actuator do its thing and then see if the arm rotates or just flops around.

The bad news is, as far as I know, you have to basically disassemble the vehicle to remove the HVAC module in order to replace this door. $15 part, but it's like finding a buried treasure to get at it.

 

chris in NY is right on on this one...I've changed at least 15 of these for this concern.