Where is those pics is a vacuum line missing?
I looked at them and cannot see anything missing.
If you are having problems with the air not switching from defrost you should verify there is no vacuum coming into the programmer, which to do so you need to open the glove box, and push back the rubber stops so it will open up enough for you to get in behind it, then towards the body/firewall of the car you should see a vacuum hose coming in, attaching to a plastic adapter, then running into the programmer, if you disconnect the black vacuum line from the plastic adapter that leads it to the programmer you should be able to verify if it has vacuum.
See this site for some pics, and better info detailing what I am talking about.
A/C Service Tech Tip: How to redirect the cooled air in late model GM cars
If you can get some better pics showing where the missing line goes I can better advise you how to proceed.