A/C "on"

AC/ACC Status:

Cars without TCS:

When A/C has been activated (manually by means of the AC switch or automatically by the ACC control unit), battery voltage is applied to pin 59 of the TRIONIC control unit.

A/C Status:

Cars with TCS:

When A/C has been activated (manually by means of the A/C switch or automatically by the ACC control module), battery positive voltage is applied to pin 37 of the ETS control module.