Inspection Procedure 21: A/C compressor relay system








OPERATION



  • When the A/C switch "ON" signal is input to the engine-ECU, the engine-ECU places the engine control 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 pressure switch
  • Damaged harness (Open circuit between A/C compressor relay and ignition switch, A/C compressor relay and engine-ECU, A/C compressor relay and A/C compressor, and open circuit between A/C compressor relay and battery)
  • Damaged connector (A/C compressor relay connector, A/C compressor connector, Engine-ECU connector)
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: D-213 engine-ECU connector

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

STEP 2. Confirmation of A/C compressor clutch driving.

  • Disconnect D-213 engine-ECU connector, Short-circuit terminal No. 19 to earth.
  • Ignition switch: ON
OK: The A/C compressor clutch drives

Q. Is the check result normal?
Go to Step 4 .
Go to Step 3 .

STEP 3. Check harness between B-16X (terminal No. 3) A/C compressor relay connector and D-213 (terminal No. 19) engine-ECU connector.

Q. Is the check result normal?
Check A/C system (Refer to GROUP 55 - Troubleshooting - Check Chart for Trouble Symptoms ).
Repair the harness wire.

STEP 4. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item 27: A/C relay

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, the vehicle equipped with the closed type DPF carries out the forcible DPF regeneration. (Refer to GROUP 17 - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).