A/C Signal: Description and Operation

This signal is sent from the A/C control module. When the A/C clutch is energized the A/C control module will make the signal line voltage low that is in series with the A/C vacuum switching valve solenoid (A/C VSV). The ECM uses this signal to adjust air/fuel mixture for the lean condition the A/C VSV solenoid creates. The vehicles engine speed will be increased slightly to prevent stalling.