Inspection Procedure 29

INSPECTION PROCEDURE 29: A/C Condenser Fan is Inoperative

A/C Condenser Fan Circuit:

CIRCUIT OPERATION
- The battery positive voltage is applied on the ECM (terminal No. 31) from the condenser fan control relay (LO).
- The battery voltage is applied on the ECM (terminal 30) from the condenser fan control relay (HI).
- When the ECM switches on those power transistors, the condenser fan control relay coil is energized, causing current to flow in the circuit.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Malfunction of the condenser fan control relay.
- Malfunction of the condenser fan motor.
- Improper connector contact, open or short-circuited harness wire.
- ECM failed.

DIAGNOSIS




STEP 1. Check harness connector C-121 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. Measure the output voltage at ECM harness side connector C-121.




1. Disconnect the connector C-121 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminal No. 31 and ground.
- Voltage should be battery positive voltage.

4. Check the condenser fan condition.
- When the terminal No. 31 is disconnected, the fan should stop.
- When the terminal No. 31 is grounded by the jumper cable, the fan should run.

5. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the voltage and fan condition normal?

YES: Go to Step 3.

NO: Refer to, Introduction to Heater, Air Conditioning and Ventilation Diagnosis in heating and Air Conditioning/Testing/Diagnosis By Symptom.

STEP 3. Measure the output voltage at ECM harness side connector C-121.




1. Disconnect the connector C-121 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminal No. 30 and ground.
- Voltage should be battery positive voltage.

4. Check the condenser fan condition.
- When the terminal No. 30 is disconnected, the fan should stop.
- When the terminal No. 30 is grounded by the jumper cable, the fan should run.

5. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the voltage and fan condition normal?

YES: Replace the ECM. Then confirm that the malfunction symptom is eliminated.

NO: Refer to, Introduction to Heater, Air Conditioning and Ventilation Diagnosis in heating and Air Conditioning/Testing/Diagnosis By Symptom.