Originally Posted by bobinyelm
I didn't check that only because the other servos work fine, moving the air to the defroster vents, or the heater outlets.
Bill is right. Check the rubber ends on the plastic 1/8 inch lines. They age and rot with heat. A leak lowers the vacuum available. There also are connections on that plastic line at the T in front of the accumulator (take off the relay center cover to see the bundle of electric wires and the plastic vacuum line) and are connections at the storage tank under the right front fender in front of the wheel. That tank may be cracked.
Then you're inside the car where the black line goes through the firewall on the right side. Take off the plastic hush panel under the dash. The violet vacuum line connects to the black line from the engine side. They pull apart. Check your vacuum there if you want. Check for vacuum there with the motor running.
Also before pulling that apart, run the motor to build vacuum. Turn it off and leave key at ON so the blower motor works. Then push different buttons on the dash control and listen for the sounds of the diaphragms moving. If you hear the diaphragms for about 20 seconds of push and they slowly weaken, you've probably got a good vacuum storage tank and connectors at the T and inside.
Most likely you've got the nipples inside the plastic connector on the corner of the programmer box sucking shut. The AC blue line does it first as theplastic softens with age and heat.
This is an early article about cutting the plastic connector out of the lines. The programmer box comes out and the top snaps off and your have access easily to put in short lines to connect the inside and outside colors--make a list first: the colors inside the programmer are different than the outside line to the diaphragms.