Inspection Procedure 4
When the A/C is Operating, Temperature Inside the Passenger Compartment does not Decrease (Cool Air is not Emitted).A/C-ECU And Air Thermo Sensor Circuit Part 1:
A/C-ECU 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 refrigerant temperature switch
- Malfunction of the A/C compressor clutch
- Malfunction of the A/C-ECU
- Malfunction of the PCM
DIAGNOSIS
Required Special Tools:
- MB991223: Test Harness Set
STEP 1. Check the defogger and outside/inside air selection damper control motor operation.
Q: Do the 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 A/C-ECU 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 A/C compressor connector B-117 and powertrain control module connector C-114 for damaged.
Q: Are A/C compressor connector B-117 and powertrain control module connector C-114 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to Harness Connector Inspection. Check that the air conditioning works normally.
STEP 5. Measure the voltage at A/C compressor connector B-117.
1. Disconnect A/C compressor connector B-117 and measure the voltage at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Disconnect powertrain control module connector C-114, and ground terminal 16.
4. Measure the voltage between A/C compressor connector B-117 terminal 1 and ground.
- The value should measure approximately 12 volts (battery positive voltage).
Q: Does the measured voltage correspond with this range?
YES : Go to Step 6.
NO : Refer to Inspection procedure 10 "A/C compressor clutch power supply system."
STEP 6. Check A/C-ECU connector C-05 for damage.
Q: Is A/C-ECU connector C-05 in good condition?
YES : Go to Step 7.
NO : Repair or replace the connector. Refer to Harness Connector Inspection. Check that the air conditioning works normally.
STEP 7. Measure the voltage at A/C-ECU connector C-05.
1. Disconnect A/C-ECU connector C-05 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" position.
4. Measure the voltage between terminal 8 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 10.
NO : Go to Step 8.
STEP 8. Check blower switch connector C-06 for damage.
Q: Is blower switch connector C-06 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 blower switch connector C-06 (terminal 1) and A/C-ECU connector C-05 (terminal 8).
Q: Is the wiring harness between blower switch connector C-06 (terminal 1) and A/C-ECU connector C-05 (terminal 8) in good condition?
YES : Check that the air conditioning works normally.
NO : Repair the wiring harness. Check that the air conditioning works normally.
STEP 10. Check air thermo sensor connector C-15 for damage.
Q: Is air thermo sensor connector C-15 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 air thermo 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 thermo sensor (outlet side) in good condition?
YES : Go to Step 12.
NO : Replace the air thermo sensor. Check that the air conditioning works normally.
STEP 12. 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 13.
NO : Replace the air thermo sensor. Check that the air conditioning works normally.
STEP 13. Check the wiring harness between air thermo sensor connector C-15 (terminals 1, 3, 4 and 5) and A/C-ECU connector C-05 (terminals 14, 16 and 13).
Q: Are the wiring harness between air thermo sensor connector C-15 (terminals 1, 3, 4 and 5) and A/C-ECU connector C-05 (terminals 14, 16 and 13) in good condition?
YES : Go to Step 14.
NO : Repair the wiring harness. Check that the air conditioning works normally.
STEP 14. Check dual pressure switch connector A-28 for damage.
Q: Is dual pressure switch connector A-28 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 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 16.
NO : Replace the dual pressure switch. Check that the air conditioning works normally.
STEP 16. Check the wiring harness between dual pressure switch connector A-28 (terminal 1) and A/C-ECU connector C-05 (terminal 4).
NOTE: Also check intermediate connector C-107. If intermediate connectors C-107 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between dual pressure switch connector A-28 (terminal 1) and A/C-ECU connector C-05 (terminal 4) in good condition?
YES : Go to Step 17.
NO : Repair the wiring harness. Check that the air conditioning works normally.
STEP 17. Check powertrain control module connector C-112 for damage.
Q: Is powertrain control module connector C-112 in good condition?
YES : Go to Step 18.
NO : Repair or replace the connector. Refer to Harness Connector Inspection. Check that the air conditioning works normally.
STEP 18. Check the wiring harness between dual pressure switch connector A-28 (terminal 2) and powertrain control module connector C-112 (terminal 69).
NOTE: Also check intermediate connectors C-116 and C-107. If intermediate connectors C-116 or C-107 are damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between dual pressure switch connector A-28 (terminal 2) and powertrain control module connector C-112 (terminal 69) in good condition?
YES : Go to Step 19.
NO : Repair the wiring harness. Check that the air conditioning works normally.
STEP 19. Check the wiring harness between A/C-ECU connector C-05 (terminal 5) and powertrain control module connector C-112 (terminal 78).
NOTE: Also check intermediate connector C-116. If intermediate connector C-116 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between A/C-ECU connector C-05 (terminal 5) and powertrain control module connector C-112 (terminal 78) in good condition?
YES : Go to Step 20.
NO : Repair the wiring harness. Check that the air conditioning works normally.
STEP 20. 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 21.
NO : Replace the compressor magnet clutch. Check that the air conditioning works normally.
STEP 21. 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 22.
NO : Replace the refrigerant temperature switch. Check that the air conditioning works normally.
STEP 22. Replace the A/C-ECU.
Q: Do the air conditioning work normally?
YES : No action is necessary and testing is complete.
NO : Replace the powertrain control module. Check that the air conditioning works normally.