I have a 2 door 1992 grand am se with the six cylinder and auto trans. I developed a problem where the tempature for the heater, vent, or AC is the same. I took some of the dash apart and all the vacuum lines apear to be working. The cable to the tempature control is moving. But no matter what temp setting I put the control to the temp stays at the constant temp as if it was set to the center temp. (not cold or warm). Any info would be appreciated. Thanks
Most likely is that the control unit is just broken, but you may have a bad heater control valve and a bad a/c unit. Check to see if the a/c compressor spins when the a/c is turned on.