Inspection Procedure 33

INSPECTION PROCEDURE 33: A/C system.

A/C Circuit:

COMMENT
- When the A/C is "ON" the ECM or the PCM turns "ON" the power transistor in the ECM or the PCM . The ECM or the PCM 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 short-circuited harness wire.
- Malfunction of the ECM or the PCM .

DIAGNOSIS

STEP 1. Check harness connector B-20 at ECM or PCM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 2.

NO: Repair or replace it. Then confirm that the malfunction symptom is eliminated.

STEP 2. Check the circuit at ECM or PCM 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. Then confirm that the malfunction symptom is eliminated.

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