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Home >> Pontiac >> 1971 >> Grand Prix 6.6L Eng, Eng CD WS, Automatic Trans >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Automatic Temperature Control >> Descriptions. Operation >> Controls >> ATC Programmer
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ATC Programmer

Unit is located on the heater core and case assembly. Varying signals from the sensor string are amplified by the D.C. amplifier and open and close relays which control an electric motor in the programmer. Movement of the motor controls vacuum, blower motor speed and position of the temperature door. No adjustments can be made on the programmer itself, but the link from the programmer to the temperature door may be adjusted.

Fig 1: ATC Vacuum Schematic - Grand Prix
G09311441Courtesy of GENERAL MOTORS COMPANY
Fig 2: Temperature Door Adjustment
G09311442Courtesy of GENERAL MOTORS COMPANY