03 - Inspection Procedure

When the A/C is Operating, Temperature Inside the Passenger Compartment does not Decrease (Cool Air is not Emitted)

A/C Compressor And Air Thermo Sensor Circuit:

Connectors Part 1:

Connectors Part 2:

CIRCUIT OPERATION
If cool air is not distributed when the A/C switch is on, the air thermo sensor or the A/C compressor relay system may be defective.

TROUBLESHOOTING HINTS
- Malformation of the air thermo sensor
- Malformation of the dual pressure switch
- Malformation of the A/C compressor relay
- Malformation of the A/C refrigerant temperature switch
- Malformation of the magnetic clutch
- Malformation of the A/C-ECU
- Malformation of the A/C-ECU
- Malformation of the ECM or PCM

DIAGNOSIS

Required Special Tools:
- MB991223: Test Harness Set

STEP 1. Check the refrigerant level.

Q: Is the refrigerant level correct?

YES: Go to Step 2.

NO: Correct the refrigerant level. (Refer to On-vehicle Service) Check that the air conditioning works normally.

STEP 2. Check the A/C compressor relay continuity.

Q: Is the A/C compressor relay in good condition?

YES: Go to Step 3.

NO: Replace the A/C compressor relay. Check that the air conditioning works normally.

STEP 3. Check the refrigerant temperature switch.

1. Immerse the refrigerant temperature sensor probe into engine oil to heat the sensor probe.

CAUTION: Does not heat the sensor probe than necessary.

2. If the oil temperature reaches the standard value, there should be continuity between the switch terminals.

Q: Is the refrigerant temperature switch operating properly?

YES: Go to Step 4.

NO: Replace the refrigerant temperature switch. Check that the air conditioning works normally.

STEP 4. Check the magnetic clutch operation.

Connect the positive battery terminal to the compressor magnetic clutch connector terminal and ground the battery (-) terminal to the body of the compressor.

Q: Can the sound of the magnetic clutch (click) be heard?

YES: Go to Step 5.

NO: Replace the compressor magnet clutch. Check that the air conditioning works normally.

STEP 5. Check the air thermos sensor (outlet side)
1. Measure the resistance between air thermo sensor (outlet side) terminal numbers 4 and 5 at two points or more.
2. Check that the measured value corresponds with approximately the shown value.

Q: Is the air thermos sensor (outlet side) in good condition?

YES: Go to Step 6.

NO: Replace the air thermo sensor. Check that the air conditioning works normally.

STEP 6. Check the air thermo sensor (inlet side)

1. Measure the resistance between air thermo sensor (inlet side) terminal numbers 1 and 3 at two points or more.
2. Check that the measured value corresponds with approximately the shown value.

Q: Is the air thermo sensor (inlet side) in good condition?

YES: Go to Step 7.

NO: Replace the air thermo sensor. Check that the air conditioning works normally.

STEP 7. Check the dual pressure switch operation.

1. Remove the dual pressure switch connector and connect the high/low pressure side terminals located on the harness side as shown in the illustration.
2. Install a gauge manifold to the high-pressure side service valve of the refrigerant line.

3. When the high/low pressure sides of the dual pressure switch are at operation pressure (ON) and the resistance is less than two ohms between the respective terminals, then the condition is normal. If open loop, replace the switch.

Q: Is the dual pressure switch operating properly?

YES: Go to Step 8.

NO: Replace the dual pressure switch. Check that the air conditioning works normally.

STEP 8. Check air thermo sensor connector C-10 and A/C ECU connector C-16 for damage.

Q: Are air thermo sensor connector C-10 and A/C ECU connector C-16 in good condition?

YES: Go to Step 9.

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

STEP 9. Check the wiring harness between air thermo sensor connector C-10 and A/C-ECU connector C-16.

Q: Are the wiring harness between air thermo sensor connector C-10 and A/C ECU connector C-16 in good condition?

YES: Go to Step 10.

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

STEP 10. Measure the voltage at A/C compressor relay connector B-13X.

1. Disconnect A/C compressor connector B-13X and measure the voltage at the wiring harness side.
2. Measure the voltage between terminal 1 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 13.

NO: Go to Step 11.

STEP 11. Check A/C compressor weary connector B-13X for damage.

Q: Is A/C compressor relay connector B-13X in good condition?

YES: Go to Step 12.

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

STEP 12. Check the wiring harness between A/C compressor relay connector B-13X and the battery.

NOTE: Also check intermediate connector A-13. If intermediate connectors A-13 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between A/C compressor relay connector B-13X and the battery in good condition?

YES: Check that the air conditioning works normally.

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

STEP 13. Measure the voltage at A/C compressor relay connector B-13X.

1. Disconnect A/C compressor connector B-13X and measure the voltage at the wiring harness side.
2. Ignition switch: ON
3. Measure the voltage between terminal 2 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 16.

NO: Go to Step 14.

STEP 14. Check A/C compressor relay connector B-13X for damage.

Q: Is A/C compressor relay connector B-13X in good condition?

YES: Go to Step 15.

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

STEP 15. Check the wiring harness between A/C compressor relay connector B-13X and the ignition switch (IG2).

NOTE: Also check intermediate connector C-122, joint connector C-101, junction block connectors C-210 and C-211.
If intermediate connector C-122, joint connector C-101 or junction block connectors C-210 or C-211 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between A/C compressor relay connector B-13X and the ignition switch (IG2) in good condition?

YES: Check that the air conditioning works normally.

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

STEP 16. Check A/C compressor relay connector B-13X and A/C compressor connector B-115 for damage.

Q: Is A/C compressor relay connector B-13X and A/C compressor connector B-115 in good condition?

YES: Go to Step 17.

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

STEP 17. Check the wiring harness between A/C compressor relay connector B-13X and A/C compressor connector B-115.

Q: Is the wiring harness between A/C compressor relay connector B-13X and A/C compressor connector B-115 in good condition?

YES: Go to Step 18.

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