Hello all, I am working on a 09 Chevrolet bus with a 6.0. Think it's just a express front clip. I am having problems with ac only blowing out the defrost. So far I have replaced the blender door as it wasn't working. And have checked the vacuum lines from the motor to the ball. What else can I look for?

 

you're still losing vacuum somewhere.
All you need to check for strong vacuum is your finger.
You can also use a smoke machine and handheld vacuum pump.