automatic air conditioning control unit power circuit inspection

1. Automatic air conditioning control unit power circuit inspection

If a malfunction is found in the auto A/C control unit power supply circuit and ground circuit, because trouble diagnosis cannot be accurately carried out, perform the control unit circuit inspection.

1. Fuse inspection

1) Inspect the meter fuse, and replace if the fuse is blown out.

2) If the fuse blows out again, check and repair the cause of the fuse blowout.

2. Inspection of circuit

1) Disconnect the connector from the control panel.

2) Start the engine.

3) Measure the voltage between the control panel connector No. 4 terminal and the ground.

Specified value: Battery voltage

If the reading is less than or equal to the standard value, repair the open circuit between the meter fuse and the control panel harness connector No. 4 terminal.
If the reading is more than or equal to the standard value, inspect the continuity between the control panel harness connector No. 18 terminal and the ground.
If there is no continuity, repair the open circuit between the control panel harness connector No. 18 terminal and the ground.

4) Turn OFF the ignition switch.

5) Measure the voltage between control panel connector No. 3 and the ground.

Specified value: Battery voltage

If the reading is less than or equal to the standard value, repair the open circuit between the meter fuse and the control panel connector No. 3 terminal.