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Ever since I've owned this car the HVAC controls have not worked right. I thought it may be the actuators, but I pulled a vacuum successfully on each of the lines going to every single actuator and they functioned fine.
I am currently just trying to get defrost to work as a starting point. To make sure everything would work, I directly connected port 1's hose (which is what gives vacuum to the whole system as I understand it) to port 3's hose. The defrost vents worked flawlessly when directly connected like that. But when connected to the actual control, nothing works at all. Just air blowing onto the floor.
On both the new one and the old one, the vacuum seems to be leaking out of this tiny hole, but I can't be too sure of that, it also seems that it's supposed to do that with certain settings.
Any thoughts or advice will be much appreciated. Thanks
The replacement valves are known to leak. Carefully disassemble the valve. Put a small amount of rubber lube on the rubber disc. Replace the plastic dart with a small screw and nyloc nut. You can then adjust the tension on the disc.
I went digging for pictures of mine. But looks like I didn't save them. You'll need a pair of little fender washers as well. Wide washer with a small hole. It's pretty straightforward.
Below is another shot of a NOS GM vacuum switch verifying OP provided vacuum diagram port numbers ...
Right side labeling is for A/C equipped cars...
The original switch port numbers were embossed in the plastic next to the port...
You will notice #2 port is capped off on the vacuum manifold...
If you were to open the switch and follow port #2 channeling maze that path ends at the small hole, that small hole is the exhaust port...
I agree with others, your switch is either leaking or the slider selector is not stopping perfectly aligned with the circuit path (maze)...
On a A/C car there are NO double sided actuators (2 hoses connected to 1 actuator) so to release energy from a circuit there must be an exhaust path...
Here is a Amazon link of the vacuum grease most use:
HVAC Control Help
