Inspection Procedure 22: A/C compressor relay system












OPERATION



  • The battery voltage is applied to the A/C compressor relay (terminal No. 5).
  • The battery voltage is applied to the A/C compressor relay (terminal No. 1) from the ignition switch. The engine-A/T-ECU (terminal No. 8) makes the power transistor in the unit be in ON position and makes currents go on the A/C compressor relay coil, and that makes the relay be in ON position.
  • When the A/C compressor is in ON position, the battery voltage is supplied to the A/C compressor (terminal No. 1) from the A/C compressor relay assembly (terminal No. 4).

FUNCTION



  • When the A/C switch ON signal is input to the engine-A/T-ECU, the engine-A/T-ECU places the A/C compressor relay in the ON position. Accordingly, the battery voltage supplied to the A/C compressor operates the magnet clutch.

PROBABLE CAUSES



  • Failed A/C compressor relay
  • Failed A/C compressor magnet clutch
  • Open/short circuit in A/C compressor relay circuit or loose connector contact
  • Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-16X A/C compressor relay connector

Q. Is the check result normal?
Go to Step 2 .
Repair or replace the connector.

STEP 2. A/C compressor relay check.

  • Check A/C compressor relay (Refer to GROUP 55 - On-vehicle Service - Power Relay Check ).

Q. Is the check result normal?
Go to Step 3 .
Replace the A/C compressor relay.

STEP 3. Perform voltage measurement at B-16X A/C compressor relay connector.

  • Remove relay, and measure at relay box side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 5 .
Go to Step 4 .

STEP 4. Connector check: D-309 ignition switch connector

Q. Is the check result normal?

    Check intermediate connectors D-230, D-401 and D-403 and repair if necessary. If intermediate connectors are normal, check and repair harness between B-16X (terminal No. 1) A/C compressor relay connector and D-309 (terminal No. 4) ignition switch connector.

    • Check power supply line for open/short circuit.
Repair or replace the connector.

STEP 5. Perform voltage measurement at B-16X A/C compressor relay connector.

  • Remove relay, and measure at relay box side.
  • Voltage between terminal No. 5 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6 .

    Check intermediate connector A-05, and repair if necessary. If intermediate connector is normal, check and repair harness between B-16X (terminal No. 5) A/C compressor relay connector and battery.

    • Check power supply line for open/short circuit.

STEP 6. Connector check: B-22 A/C compressor assembly connector

Q. Is the check result normal?
Go to Step 7 .
Repair or replace the connector.

STEP 7. Perform voltage measurement at B-22 A/C compressor assembly connector.

  • Disconnect connector, and measure at harness side.
  • Remove B-16X (terminal No. 4 and No. 5) A/C compressor relay and short-circuit of harness side connector.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 8 .

    Check and repair harness between B-22 (terminal No. 1) A/C compressor assembly connector and B-16X (terminal No. 4) A/C compressor relay connector.

    • Check output line for open/short circuit.

STEP 8. Perform voltage measurement at D-212 engine-A/T-ECU connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 8 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 12 .
Go to Step 9 .

STEP 9. Connector check: D-212 engine-A/T-ECU connector

Q. Is the check result normal?
Go to Step 10 .
Repair or replace the connector.

STEP 10. Check harness between B-16X (terminal No. 3) A/C compressor relay connector and D-212 (terminal No. 8) engine-A/T-ECU connector.

  • Check earthing line for open/short circuit.

Q. Is the check result normal?
Go to Step 11 .
Repair the damaged harness wire.

STEP 11. M.U.T.-III data list

  • Item 93: A/C compressor relay

  1. Engine: Idling
  2. A/C set temperature:

    Maximum Cool when temperature in cabin is 25°C or more
    Maximum Hot when temperature in cabin is 25°C or less
OK:
    ON (when A/C is ON)
    OFF (when A/C is OFF)

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-A/T-ECU.

STEP 12. Connector check: D-212 engine-A/T-ECU connector

Q. Is the check result normal?
Go to Step 13 .
Repair or replace the connector.

STEP 13. Check harness between B-16X (terminal No. 3) A/C compressor relay connector and D-212 (terminal No. 8) engine-A/T-ECU connector.

  • Check earthing line for damage.

Q. Is the check result normal?
Go to Step 14 .
Repair the damaged harness wire.

STEP 14. Connector check: D-309 ignition switch connector

Q. Is the check result normal?
Go to Step 15 .
Repair or replace the connector.

STEP 15. Check harness between D-309 (terminal No. 4) ignition switch connector and B-16X (terminal No. 1) A/C compressor relay connector.
note Before checking harness, check intermediate connectors D-230, D-401 and D-403, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 16 .
Repair the damaged harness wire.

STEP 16. Check harness between battery and B-16X (terminal No. 5) A/C compressor relay connector.
note Before checking harness, check intermediate connector A-05, and repair if necessary.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 17 .
Repair the damaged harness wire.

STEP 17. Check harness between B-16X (terminal No. 4) A/C compressor relay connector and B-22 (terminal No. 1) A/C compressor assembly connector.

  • Check output line for damage.

Q. Is the check result normal?
Replace the A/C compressor magnet clutch.
Repair the damaged harness wire.