01 - Inspection Procedure

Air Conditioner does not Operate

A/C-ECU Power Supply Circuit:

Connector:

CIRCUIT OPERATION
The power supply circuit (including the ground) to the A/C-ECU may be faulty.

TROUBLESHOOTING HINTS
- Malfunction of the A/C-ECU
- Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:
- MB991223: Test Harness Set







STEP 1. Measure the voltage at A/C-ECU connector C-16 in order to check the line from the ignition switch (IG2).

1. Disconnect A/C-ECU connector C-16, and measure the voltage at the wiring harness side.
2. Ignition switch: ON
3. Measure the voltage between terminal 10 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).

Q: Does the measured voltage correspond with this range?

YES: Go to Step 4.

NO: Go to Step 2.




STEP 2. Check A/C-ECU connector C-16 for damage.

Q: Is A/C-ECU connector C-16 in good condition?

YES: Go to Step 3.

NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the air conditioning works normally.







STEP 3. Check the wiring harness between A/C-ECU connector C-16 and the ignition switch (IG2).

NOTE: Also check junction block connectors C-211 and C-214. If junction block connectors C-211 or C-214 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between A/C-ECU connector C-16 and the ignition switch (IG2) in good condition?

YES: Go to Step 4.

NO: Repair the wiring harness. Check that the air conditioning works normally.







STEP 4. Measure the resistance at A/C-ECU connector C-16 in order to check the ground circuit to the A/C-ECU.

1. Disconnect A/C-ECU connector C-16, and measure at the wiring harness side.
2. Measure the resistance between terminal 12 and ground.
- The measured value should be 2 ohms or less.

Q: Does the measured resistance value correspond with this range?

YES: Replace the A/C-ECU, and check that the air conditioning works normally.

NO: Go to Step 5.




STEP 5. Check A/C-ECU connector C-16 for damage.

Q: Is A/C-ECU connector in good condition?

YES: Go to Step 6.

NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the air conditioning works normally.







STEP 6. Check the wiring harness between A/C-ECU connector C-16 and the ground.

NOTE: Also check joint connector C-06. If joint connector C-06 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between A/C-ECU connector C-16 and the ground in good condition?

YES: Replace the A/C-ECU, and check that the air conditioning works normally.

NO: Repair the wiring harness. Check that the air conditioning works normally.