Inspection Procedure 23: 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 condenser fan relay, A/C compressor relay and engine-ECU, A/C compressor relay and A/C compressor, and open circuit between A/C compressor relay and relay box)
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, and earth terminal No. 40.
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. 40) 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 .

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 ).