I have a 1981 vette just repaired a/c all working but a/c only blowing to floor. Does anyone know where the switch is inside the duct system to divert the air to the ventss ? I have the dash apart and main vents and ducts out, cant find switch. PLEASE HELP ITS HOT DOWN HERE

 

Should be vaccuum operated. Check vaccuum source and lines.

 

The problem is that heater is the default position (no vac. or vac. leak) due to being designed in the north. Vent should be default. Very safe bet the problem is 1 OR 2:
1) The vac. line from engine is damaged from heat - a small plastic tube that goes in below the hood theft switch into wiper valley. Replacing most of engine side w/ hose will fix. OR
2) The vac. switch itself is not switching due to vac. leak as the usually plastic rivet is not holding the 2 main switch parts together well. Besides replacing, it is also possible to tighten this &/or lube w/ a thin layer of white lithium grease or vasoline to fix.
3) If you have a heater, the small hose to heater hose valve underhood probably also needs replacing. Block w/o heater.

PS The design problem comment is not intended to be offensive to any of our northern friends.

 

thanks for the help, I have located the vacuum line in the engine side can you tell me where the vacuum switch is located so I can lube it while I have the dash out ?
Thanks

 

i had the same problem ... what i did was GET A ASSEMBLY MANUAL... there are very good pictures of the vaccume system showing all the diaphrams and what color vaccume line go to which diaphram---i used colored pencils and color coated all the lines too match the same color of the stripe on each line--- it was very straight forward and i got all my diaphrams to open and close ,,,diverting the air flow---- it also shows all the componits such as the vaccume switch(its the switch in the console that has all the vaccume lines going to it----1 line going to that switch is the source vaccume(vaccume feed to the switch)the rest are loads opening and closing different vaccume diaphrams---such as heat/defrost----another closes the flapper in the wiper tray while opening the passenger footwell diaphram(to recirulate cabin air)--- if you get the manual and color coat the lines on the diagram you will have no problem figuring it out-- actually it was pretty e-z--- find the source vaccume line(one of the lines will have suction on it(hopefully) then i took a small coulping for splicing 2 vaccume lines toughter and started taking one line (load) at a time and connected it to the source vaccume line and it would operate a diaphram and so on

 

GREAT thanks know where i can get the assembly manual ?

 

Most vette parts stores carry the assembly manuals, try ecklers.com, I know they have it.

 

I had the same problem on my 69. It turned out to be one of the heater acuators. Don't know if your's is the same set up but you can test them by puting a vac. hose on it and suck on it by mouth, and see if works it. Another good idea that I use to find a vac leak is to blow cigarette smoke through it. If it's got a hole, you'll find it. I would say it is the acuator though.

 

Ebay sells shop manuals too

 

The vac. control switch is in the console attached to the Vent/A/C control lever.

 

I found two kinks in the vacuum line near the distributor housing. I would start your search there first. It does sound like a low or no vacuum condition. Taking the ignition shield on and off has a tendency to damage the vacuum line. Good luck finding the problem. I hope it is an easy fix like mine was.

Ron