Hello friends ... I have a little problem in my 91 Firebird v6 ...
When I put the air conditioning, there is no air coming from the central or lateral diffusers, only air comes out in the direction of the feet and towards the front window.
I do not hear the lid move when the air conditioner is operated.

However everything works well, cold air, hot air ...

The only problem is that, there is no air coming from the central and lateral diffusers.

Any ideas? Why do not I hear the "lid" heard when the air conditioner or fan is operated?

Forgive me if I have not expressed myself clearly.

 

Is the vacuum line hooked up under the hood? It defaults to defrost if no vacuum is present

 

Yes, everything works correctly. In fact, I get the air through the diffuser of the front window, and also the diffusers in the direction of the feet.
The only problem is that I do not get through the central diffusers.

 

You will get air in those locations if the vacuum is lost. Here's some pictures. Find the 2 hard lines under the hood at the firewall center/pass area. 1 of those hard lines goes to the Heater Control Valve, the other is Tee'd to vacuum port on plenum.

 

Thanks everyone for your help. I will try to see if I can solve the problem and tell you how I have gone.

 

Hello again friends ... I've finally been able to fix the air leak. The problem was that one of the plastic tubes, the red wire was broken. I removed the piece and fixed the piece with glue. Correct result. Everything works again. Thank you all!!!!

 

Good deal! Did you hear it hissing?

 

Yes ... that's how I discovered where the problem came from