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Automatic A/C System Functional Check

  1. Perform these steps to verify A/C control system is functioning properly, or after performing temperature air valve recalibration. See ADJUSTMENTS. If any problems are encountered, diagnose and repair them before proceeding through following steps.
  2. With outside temperature at least 50°F (10°C), idle engine until it is warm. Place system in AUTO mode and set temperature for maximum heat. After 30 seconds, check for a strong flow of warm air from the floor outlet. This indicates blower high speed is working.
  3. Change temperature to maximum cooling. Blower speed should diminish momentarily, then increase again to high speed. During the shift, air should begin to flow from instrument panel outlets. Air flow from floor outlet should stop. Operate at maximum cooling for one minute. Discharge temperature at center outlet should be at least 20°F (7°C) lower than ambient temperature.
  4. With engine still running, change temperature setting to any number higher than inside vehicle temperature. Air inlet valve should close. Valve closing should be heard and a reduction of blower motor speed should be noticed.
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