I have a '97 Mercury Cougar. The climate control system was working fine, and it still puts out cold air, or hot air, depending on whether you select heating or cooling. But now when I turn on the climate control the force of air only comes out through the defroster vents and not through the dash vents no matter what position I put the selector switch on. Before, when I would switch from A/C to defroster or panel setting, you could hear a vent "door" on the passenger side near the firewall closing or opening to channel the air one way or the other to the different vents. I don't hear that sound anymore and I can't figure out where that door is located. I checked all the fuses and they look good. Is there a solenoid that controls the opening and closing of that vent door? Maybe it's just stuck in one position and needs cleaning. Any ideas? Thanks.