Inspection Procedure 32

INSPECTION PROCEDURE 32: A/C system










COMMENT

- When the A/C is "ON" the ECM[ M/T] or the PCM[ A/T] turns "ON" the power transistor in the ECM[ M/T] or the PCM[ A/T]. The ECM[ M/T] or the PCM[ A/T] delays A/C engagement momentarily while it increases idle r/min. Then the A/C compressor clutch relay coil will be energized.
With this, the A/C compressor clutch relay turns "ON", and the A/C compressor clutch operates.

TROUBLESHOOTING HINTS (The most likely causes for this case: )

- Malfunction of the A/C control system.
- Improper connector contact, open circuit or shorted harness wire.
- Malfunction of the ECM[ M/T] or the PCM[ A/T].

DIAGNOSIS

STEP 1. Check harness connector B-20 at ECM [M/T] or PCM [A/T] for damage.





Q. Is the harness connector in good condition?

YES Go to Step 2.

NO Repair or replace it. Harness Connector Inspection.
Then confirm that the malfunction symptom is eliminated.

STEP 2. Check the circuit at ECM [M/T] or PCM [A/T] connector B-20.





(1)Disconnect the connectors B-20 and measure at the harness side.
(2)Turn the ignition switch to the "ON" position.





(3)Measure the voltage between terminal No. 81 and ground.

- Voltage should be battery positive voltage.
(4)Using a jumper wire, connect terminal No. 81 to ground.

- A/C compressor clutch relay should turn "ON".
(5)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the voltage and A/C compressor relay condition normal?

YES Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Encrypted Code Registration Criteria Table.
Then confirm that the malfunction symptom is eliminated.

NO : Introduction [Manual A/C], 55B, Automatic A/C Diagnosis - Introduction To Heater, Air Conditioning And Ventilation Diagnosis Introduction [Automatic A/C]. Then confirm that the malfunction symptom is eliminated.