temp control on AC stays on full cold on 1993 Chevrolet Caprice

temp control on AC system stays full cold no matter where you slide the adjustment lever. When on heater it is still cold. no heat or even warm air blows. Compressor goes on and off with switch.

Asked by for the 1993 Chevrolet Caprice
Check to see if the temperature control cable is moving when you slide the adjustment lever, the temperature control door under the dash should move from hot to cold when you move the temp control lever. If the temperature door operation is OK then check the heater hoses under the hood. With the engine warm, both heater hoses should be warm. If only one hose is warm then you have a coolant flow issue through the heater core. This could be caused by a faulty heater water valve if equipped or a restricted heater core.