95 Heater/AC controls not working right

[Bigbad1967]

My A/C works fine. Move the control to Heat and nothing happens. The doors under the dash close but heat dosnt come out of the floor vents. Who ever had this van before me had a sorry A** mechanic working on it? What I would like to have is a complete diagram of how all the Heater/Ac controls work and a diagram of the vacuum lines for a 1995 Chevy astro Tiara conversion van. Thanks for any help. It is surly apprieciated

[Kings-x59]

Man, that's really the rub isn't it...
I don't think I've ever seen a "complete" vacuum hose diagram. I've never seen more than the basic emissions related vacuum hoses in a diagram.
But, you are on the right track. If the AC blows, then the blower is working, so it has to be a stuck damper problem. And, most likely a vacuum hose specifically. My van is a fair bit older than yours, but I had a problem with the dampers not moving. What I found was a vaccum chamber for the AC system, buried down near the right front wheel well with the hose dry rotted and split. The only way I've found to trace vacuum problems is to grab a hose and trace it to both ends. if it's a rubber hose the problems is usually at one end or the other. usually a spit, sometimes on the inside face of the hose. If it's a molded plastic vacuum tube, I've found chafed, or abraded holes from rubbing against metal. Unfortunately you need to trace them all. Vacuum leaks are quirky. The leak might not be right at the AC.
One last thought -I've read a few posts regarding the more recent year models about a vacuum hose that routes up and over on the firewall that gets toasted by engine heat that has caused similar problems. Where vacuum lines are concerned, patience is the best tool in your box... a couple of beers don't hurt either.
you'll find it.

[Bigbad1967]

Thanks. Also the air blows fine when idling and going down the road under light conditions, but going up hills or putting the engine under strain the vents stop blowing and seem to stop blowing from anywhere. One more thing, When I put the control on defrost the control hisses pretty loudly from the vacuum sucking air. ?????? Thanks again for any help...