I think you are describing the aspirator hose to the in car temp sensor located just above the two center vents. that hose takes the cars inside air and sends it to the programmer to compare in car temp with temperature set on the roller wheel of the automatic climate control. If that hose is off at either end the comparison will be inaccurate and the system will not modulate the temperature and fan speed accurately. With the glove box insert removed, reach to the left inside the dash were the hose connects to the sensor base. Twist the collar clockwise I believe and that should allow the sensor to lift up out of the dash. and if its disconnected there just push up on the hose and twist the collar to secure it to the sensor. Any leaks in that hose will cause the system to be slow to act or be inaccurate. There is a "thermister" in that little grille of the sensor that changes value electrically to modulate temperature of air discharged and which direction air flows i.e. dash or floor or a combination of both.