heat/ac control problem

Well, I finally decided to register here rather than just lurk around from time to time. I just started to fix a few things on my 97 gt after letting it sit for about 4 months. One thing I replaced is the blower motor resistor switch and that worked but I am still having problems. My heat/ac blow out of everything no matter what setting it is on. Is this just the control switch or is there something more I should be checking before I buy a new Climate Control Panel???? Thanks in advance for any guidance.

Put your head up under the dash and move the controls. Listen for hissing. You may have a vacuum leak.

well that is a good question, because I thought I heard hissing a while back but I dont now, and the problem remains.