Inspection Procedure 31

INSPECTION PROCEDURE 31: A/C System

A/C Circuit:

COMMENT
- When the A/C is "ON" the PCM turns "ON" the power transistor in the PCM. 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 shorted harness wire.
- Malfunction of the PCM.

DIAGNOSIS

STEP 1. Check harness connector B-21 at 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 PCM connector B-21.







1. Disconnect the connectors B-21 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 PCM. When 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 [Manual A/C], Manual A/C Diagnosis Automatic A/C Diagnosis - Introduction To Heater, Air Conditioning And Ventilation Diagnosis [Automatic A/C]. Automatic Air Conditioning Then confirm that the malfunction symptom is eliminated.