2000 Chevrolet Blazer

Heater problem
2000 Chevy Blazer 6 cyl Two Wheel Drive Automatic 133800 miles

Hi, I have no heat going to floor, or defrost+floor, or floor+panel. I have heat on defrost and panel. When I have it on floor it goes to defrost since it is the default. So the heat seems to be working fine just the door is not opening properly.
I read in the other thread to follow a small black line under the hood, but I think it was for a no heat problem.
I opened the dashboard, and can see several colored lines, could someone tell me what these lines do:


If I am not mistaken Black is the source. As far as I can see under, it is not broken. Could it be the climate control unit not signaling to open? Is there a quick way to test these lines out? I tried removing one by one to see what they do but could not get much further. Any help would be appreciated.
January 10, 2008.

Finally I had a chance to look under the driver and passanger seats. There are vacuum lines to open and close doors. The lever seems to move when I change switch to floor from panel or defrost implying the lines are not leaking. The lines have a small vacuum pressure. The lever to open floor door may be broken. And there is no easy way to tell. Dealer is asking 3.5 hrs of labor and other place wants 8 hrs of labor to repair. They will remove dash board and anything to get to the door. To me this repair cost of about $400 is not worth fixing the floor heat. So I will open it myself, when I have the time to do it.

There is one thing that worries me. Can anyome please tell me if I should be aware of anythig in particulr about airbags? It appears that I have to take out passengar air bag, but not driver side airbag. Are they easy to take off? Any advice would be appreciated.

Jan 17, 2008.
My blazer has a similar problem. Lots of hot air through the defrost and dash, just no floor heat. I checked behind the glove box too. No problems there. I followed the vacuum lines around and the blue and red ones went to the heat/defrost door in question directly above the accelerator pedal. It appeared the lever was flopping around. I will try to make a repair without removing the whole dash. Read my post to see if the problem is the same. You can access this actuator by just removing the cover below the steering column. Quick and easy to get at the actuator.

I'll post when I figure something out this weekend.

Apr 4, 2008.
My 2000 blazer just developed the same problem a couple days ago when it got cold. I have tracked it down to a broken door for the floor vents. It looks like it moves, but the door doesn't move. The cam for the door moves.

Apr 4, 2008.
I end up taking a 14-gauge electric wire about 2 feet long and sticking up through the driver side botton vent. I had to bend it to make it go through the vent and I was able to open the door. The heat came right through the vent. Woo hoo! I left the wire there for another day to remove and fix the problem correctly. It has been a few week and just waiting to get a chance to spare a few hours to do something about it.

Apr 6, 2008.
Pay close attention when putting it back together. You don't want to have to do it a second time.

Apr 7, 2008.