A/C only coming out of defrost vents

first thing to do is see if you have a vacuum line off. then check to see if there is a hole in the line going to the heater, that includes from the engine to block on the firewall and from there to the heater control. It could be your control, but i do not know if you will hear it with the engine running. you may be able to feel it though. check on your fender wells for the canister. it can also be down outside in the tire area. there also should be a check valve between the engine and heater control. Here is a guide to help you see what to look for so you can fix the problem.

https://www.2carpros.com/articles/air-vents-stay-in-the-defrost-position

Please run down this guide and report back

Cheers

Okay sorry, i have not been able to work on it for a while. found the vacuum canister, tested it with a hand operated pump, and it seems to be working just fine. i also replaced the switch on the dash which controls where the air is directed. same problem still exists.

the leak must be before the switch that was replaced, but i do not know which hose is supposed to supply the vacuum to the switch, or where it comes from.

i guess i need a diagram of the vacuum system so i can try and track down the leak. any ideas on where i might be able to obtain one?

thanks again for the help.

there is a check valve that may have gone bad, those are usually one way to keep vacuum in the system. I am sending a diagram along and you can blow it up or print it. I would check to see if you are getting vacuum to the motor that moves the air as usually when the vacuum goes out the defrost stays on.

Check out the diagrams (Below). Please let us know what you find.

I found the break at the tee in the vacuum line under the hood near the evaporator core :) all fixed. I love this site.