Here's the new deal. I had issues with the blower motor and heater control unit earlier today. I have since replaced the fuse for the blower motor and the heater control unit is no longer locked in one position.

However, when I slide from one position (AC for example) to another (blended heat and defrost for example) there is no change in air flow. The air flow is constantly flowing through the defrost and heat vents. This is not a major problem at this time considering it is winter in the midwest. But...Since I "coersed" the heater control slider to go from AC back to blended heat and defrost, the thing sounds like an annoyed cottonhead. I realize that because of my assistance I lent to the slider switch, I have probably broken something internally and this unit will need to be replaced. However, for the time being please help me with these two questions. Why is this thing constantly hissing at me? And what can I do about it?

Any help would be greatly appreciated...Guss