Ford Repair: Air Condition/Heating, ford f 250, vacuum hoses

Question
I own a 2001 Ford F-250 Powerstroke 7.3T
Problem: My Air Conditioning and Heater only blows through the defrost ports.  The floor and dash ports has no air flow no matter where you set the switch to. I have not attempted to repair the problem due to my lack of knowledge of where to begin.  The control switch on the panel appears to be switching from heat to air conditioning.  The temperature control switch appears to be working properly.  I feel that this maybe a vacuum issue or a switch underneath the dash that controls the main damper and it is stuck allowing air to only flow to the defrost ports.

If you have any ideas on repairing the problem your expert advice would be greatly appreciated.  I live in Greenwood Indiana and the forecast is going into the high 80' to low 90's by the end of this week.

Answer
Yes, sounds like a vacuum leak. Check under the dash for any small vacuum hoses that have fallen off; see if you can find the vacuum hose under the hood and make sure it is connected, should be a small black plastic line. Make sure the vacuum pump is working too.