I have an 83 Chevy S10 that the a/c and heater doesn't work correctly. The fan turns on. There's no a/c and the air doesn't work out any of the other modes except the defrost. I can slide the control to any position, but will blow out the defroster. I've tested all the electrical and seems to be fine. There doesn't seem to be any vacuum to any of the units under the dash and I can't find where the vacuum lines goes through the firewall and to where the vacuum lines will be connected to the engine. I'd rather not remove the dash just to locate the vacuum lines. Can you or anyone help?

find your vacuum tank under the hood and make sure your getting vacuum to that

I'm getting vacuum at both sides of the vacuum ball. There's vacuum on the big tube and I can blow and suck through the small tube.

sounds like a dash issue then...you'll have to remove the head and manually check everything