A/C Signal: Testing and Inspection

NOTE: A number of problems, in addition of a defective A/C switch, can cause A/C system malfunctions.

1. With engine at operating temperature and running at idle, probe ECM terminal E19-15 (green wire) with positive voltmeter lead and ground negative lead.
2. Turn A/C switch "ON." Meter should read battery voltage, indicating that switch is functioning properly and A/C request signal is reaching the ECM.
3. If problems are indicated, check wiring circuits and connections. For complete diagnosis and repair information on the air conditioning system, refer to HEATING, VENTILATION AND AIR CONDITIONING.