A/C Signal: Description and Operation

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