Diagnosis And Testing - Rear Window Defogger Switch

For instructions on how to use the DRB III(R) scan tool or the a/c heater control self-diagnostics to test the control, (Refer to DIAGNOSIS AND TESTING ). The problem is not with the a/c heater control if no trouble codes are found. The next step should be to check the rest of the system after the MTC or ATC head is checked.