- Turn the ignition switch OFF.
- Remove the A/C diode C from the right side of dash.
- Check for current flow in both directions between the No.1 and No.2 terminals of the A/C diode C.
A/C DIODE C
Is there current flow in only one direction?
YES - Go to step 20.
NO - Replace the A/C diode C. 
- Turn the ignition switch ON (II).
- Measure the voltage between the No.2 terminal of the A/C diode C 2P connector and body ground.
A/C DIODE 2P SOCKET
Wire side of female terminals
Is there battery voltage?
YES - Go to step 22.
NO - Repair open in the wire between the A/C thermostat and the A/C diode C.
- Turn the ignition switch OFF.
- Reinstall the A/C diode C.
- Disconnect the push switch 10P connector.
- Turn the ignition switch ON (II).
- Measure the voltage between the No. 3 terminal of the push switch 10P connector and body ground.
PUSH SWITCH 10P CONNECTOR
Wire side of female terminals
Is there battery voltage?
YES - Go to step 27.
NO - Repair open in the wire between the A/C diode C and the push switch.
- Turn the ignition switch OFF.
- Disconnect the heater fan switch 7P connector.
- Check for continuity between the No. 4 terminal of the push switch 10P connector and the No. 3 terminal of the heater fan switch 7P connector.
PUSH SWITCH 10P CONNECTOR
Wire side of female terminals
HEATER FAN SWITCH 7P CONNECTOR
Wire side of female terminals
Is there continuity?
YES - Go to step 30.
NO - Repair open in the wire between the push switch and the heater fan switch.