Inspection Procedure 4

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 Part 1:

A/C Compressor And Air Thermo Sensor Circuit Part 2:

TECHNICAL DESCRIPTION (COMMENT)
If cool air is not distributed when the A/C switch is on, the air thermo sensor or the A/C compressor clutch relay system may be defective.

TROUBLESHOOTING HINTS
- Malfunction of the air thermo sensor
- Malfunction of the dual pressure switch
- Malfunction of the A/C compressor clutch relay
- Malfunction of the A/C refrigerant temperature switch
- Malfunction of the A/C compressor clutch
- Malfunction of the heater control
- Malfunction of the ECM
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.

DIAGNOSIS

Required Special Tools:
- MB991223: Test Harness Set

STEP 1. Check the rear window defogger and outside/inside air selection damper control motor operation.

Q: Do the rear window defogger and outside/inside air selection damper control motor work normally?

YES: Go to Step 2.

NO: Refer to Inspection procedure 9 "Malfunction of the heater control power supply system".

STEP 2. Check the blower motor operation.

Q: Does the blower motor work normally?

YES: Go to Step 3.

NO: Refer to Inspection procedure 5 "Blower Fan and motor does not turn."

STEP 3. Check the A/C compressor.
Check the A/C compressor for compressor oil leaks.

Q: Is the check result satisfactory?

YES: Go to Step 4.

NO: Replace the A/C compressor or the expansion valve.







STEP 4. Check the A/C compressor clutch relay continuity.
Follow the table to check the A/C compressor clutch relay for continuity.

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

YES: Go to Step 5.

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

STEP 5. Measure the voltage at A/C compressor connector A-36.




1. Disconnect A/C compressor connector A-36 and measure the voltage at the harness side.







2. Disconnect engine control module connector C-121, and ground terminal 8.
3. Turn the ignition switch to the "ON" position.




4. Measure the voltage between terminal 1 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts?

YES: Go to Step 16.

NO: Go to Step 6.

STEP 6. Measure the voltage at A/C compressor clutch relay connector B-13X.




1. Disconnect A/C compressor connector B-13X and measure the voltage at the relay box side.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminal 2 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts?

YES: Go to Step 9.

NO: Go to Step 7.




STEP 7. Check A/C compressor clutch relay connector B-13X for loose, corroded or damaged terminals, or terminals pushed back in the connector.

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

YES: Go to Step 8.

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




STEP 8. Check the wiring harness between A/C compressor clutch relay connector B-13X (terminal 2) and the ignition switch (IG2).









NOTE: Also check intermediate connector C-124, joint connector 2. C-101, junction block connectors C-210 and C-211. If intermediate connector C-124, joint connector 2. C-101, or junction block connectors C-210 or C-211 is loose, corroded or damaged terminals, or terminals pushed back in the connector., repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between A/C compressor clutch relay connector B-13X (terminal 2) and the ignition switch (IG2) in good condition?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Cope with intermittent Malfunctions.

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

STEP 9. Measure the voltage at A/C compressor clutch relay connector B-13X.




1. Disconnect A/C compressor clutch relay connector B-13X and measure the voltage at the relay box side.




2. Measure the voltage between terminal 1 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts?

YES: Go to Step 12.

NO: Go to Step 10.




STEP 10. Check A/C compressor clutch relay connector B-13X for loose, corroded or damaged terminals, or terminals pushed back in the connector.

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

YES: Go to Step 11.

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




STEP 11. Check the wiring harness between A/C compressor clutch relay connector B-13X (terminal 1) and the battery.






NOTE: Also check intermediate connector A-29. If intermediate connector A-29 is loose, corroded or has damaged terminals, or terminals pushed back in the connector, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between A/C compressor clutch relay connector B-13X (terminal 1) and the battery in good condition?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Cope with intermittent Malfunctions.

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







STEP 12. Check A/C compressor clutch relay connector B-13X and A/C compressor connector A-36 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is A/C compressor clutch relay connector B-13X and A/C compressor connector A-36 in good condition?

YES: Go to Step 13.

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










STEP 13. Check the wiring harness between A/C compressor clutch relay connector B-13X (terminal 4) and A/C compressor connector A-36 (terminal 1).

NOTE: Also check intermediate connector A-13. If intermediate connector A -13 is loose, corroded or has damaged terminals, or terminals pushed back in the connector., repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between A/C compressor clutch relay connector B-13X (terminal 4) and A/C compressor connector A-36 (terminal 1) in good condition?

YES: Go to Step 14.

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







STEP 14. Check engine control module connector C-121 and A/C compressor clutch relay connector B-13X for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are engine control module connector C-121 and A/C compressor clutch 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 engine control module connector C-121 (terminal 8) and A/C compressor clutch relay connector B-13X (terminal 3).

Q: Is the wiring harness between engine control module connector C-121 (terminal 8) and A/C compressor clutch relay connector B-13X (terminal 3) in good condition?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Cope with intermittent Malfunctions.

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




STEP 16. Check the A/C compressor clutch operation.
Connect the positive battery terminal to the compressor A/C compressor clutch connector terminal and ground the battery (-) terminal to the body of the compressor.

Q: Can the sound of the A/C compressor clutch (click) be heard?

YES: Go to Step 17.

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

STEP 17. Check the refrigerant temperature switch.

CAUTION: Do not heat more than necessary.




1. Dip the metal part of the refrigerant temperature switch into engine oil and increase the oil temperature using a gas burner or similar.







2. When the oil temperature reaches the standard value, check that voltage is supplied between the terminals.

NOTE: When the oil temperature is 150 °C (302 °F) or more and there is no continuity, the resistance will not be 2 Ohm or lower until the oil temperature reduces to 120 °C (248 °F) or less.

Q: Is the refrigerant temperature switch operating properly?

YES: Go to Step 18.

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

STEP 18. Measure the voltage at heater control connector C-16.




1. Disconnect heater control connector C-16 and measure the voltage at the relay box side.
2. Turn the ignition switch to the "ON" position.
3. Turn the blower switch to the "1(Lo)" position.




4. Measure the voltage between terminal 8 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts?

YES: Go to Step 21.

NO: Go to Step 19.




STEP 19. Check blower switch connector C-125 and heater control connector C-16 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is blower switch connector C-125 and heater control connector C-16 in good condition?

YES: Go to Step 20.

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




STEP 20. Check the wiring harness between blower switch connector C-125 (terminal 1) and heater control connector C-16 (terminal 8).

Q: Is the wiring harness between blower switch connector C-125 (terminal 1) and heater control connector C-16 (terminal 8) in good condition?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Cope with intermittent Malfunctions.

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

STEP 21. 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 22.

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

STEP 22. 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 23.

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







STEP 23. Check air thermo sensor connector C-10 and heater control connector C-16 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are air thermo sensor connector C-10 and heater control connector C-16 in good condition?

YES: Go to Step 24.

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







STEP 24. Check the wiring harness between air thermosensor connector C-10 (terminals 1, 3, 4 and 5) and heater control connector C-16 (terminals 14,16 and 13).

Q: Are the wiring harness between air thermo sensor connector C-10 (terminals 1, 3, 4 and 5) and heater control connector C-16 (terminals 14,16 and 13) in good condition?

YES: Go to Step 25.

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

STEP 25. 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) the resistance should less than two ohms between the terminals. If open circuit, replace the switch.

Q: Is the dual pressure switch operating properly?

YES: Go to Step 26.

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







STEP 26. Check dual pressure switch connector A-25 and heater control connector C-16 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are dual pressure switch connector A-25 and heater control connector C-16 in good condition?

YES: Go to Step 27.

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







STEP 27. Check the wiring harness between dual pressure switch connector A-25 (terminal 1) and heater control connector C-16 (terminal 4).






NOTE: Also check intermediate connector C-111 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-111 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between dual pressure switch connector A-25 (terminal 1) and heater control connector C-16 (terminal 4) in good condition?

YES: Go to Step 28.

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







STEP 28. Check dual pressure switch connector A-25 and engine control module connector C-119 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are dual pressure switch connector A-25 and engine control module connector C-119 in good condition?

YES: Go to Step 29.

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










STEP 29. Check the wiring harness between dual pressure switch connector A-25 (terminal 2) and engine control module connector C-119 (terminal 45).

NOTE: Also check intermediate connectors C-111 and C-124 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-111 or C-124 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between dual pressure switch connector A-25 (terminal 2) and engine control module connector C-119 (terminal 45) in good condition?

YES: Go to Step 30.

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







STEP 30. Check heater control connector C-16 and engine control module connector C-121 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are heater control connector C-16, engine control module connector C-121 in good condition?

YES: Go to Step 31.

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







STEP 31. Check the wiring harness between heater control connector C-16 (terminal 5) and engine control module connector C-121 (terminal 24).






NOTE: Also check intermediate connector C-124 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-124 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between heater control connector C-16 (terminal 5) and engine control module connector C-121 (terminal 24) in good condition?

YES: Go to Step 32.

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

STEP 32. Check the refrigerant level.
Use the refrigerant recovery station to remove all of the refrigerant, and then calculate the amount of the refrigerant and charge it.

Q: Is the refrigerant level correct?

YES: Go to Step 33.

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

STEP 33. Replace the heater control.

Q: Do the air conditioning work normally?

YES: No action is necessary and testing is complete.

NO: Replace the engine control module connector. Check that the air conditioning works normally.