AUTOMATIC A/C TROUBLESHOOTING STRATEGY
Use these steps to plan your diagnostic strategy. If you follow them carefully, you will be sure that you have exhausted most of the possible ways to find a heater, air conditioning and ventilation fault.
- Gather information from the customer.
- Verify that the condition described by the customer exists.
- Find the malfunction by following the Symptom Chart. (Refer to «SYMPTOM CHART»(ref-394962-S05066547882011040900000) )
- Verify malfunction is eliminated.
HOW TO CONNECT THE SCAN TOOL (M.U.T.-III)
Required Special Tools
- MB991958: Scan Tool (M.U.T.-III Sub Assembly) MB991824: Vehicles Communication Interface (V.C.I.) MB991827: M.U.T.-III USB Cable MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
| CAUTION | To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. |
Scheme 1
- Ensure that the ignition switch is at the "LOCK" (OFF) position.
- Start up the personal computer.
- Connect special tool MB991827 to special tool MB991824 and the personal computer.
- Connect special tool MB991910 to special tool MB991824
- Connect special tool MB991910 to the data link connector.
- Turn the power switch of special tool MB991824 to the "ON" position. NOTE: When the special tool MB991824 is energized, the special tool MB991824 indicator light will be illuminated in a green color.
- Start the M.U.T.-III system on the personal computer. NOTE: Disconnecting scan tool MB991958 is the reverse of the connecting sequence, making sure that the ignition switch is at the "LOCK" (OFF) position.
HOW TO READ AND ERASE DIAGNOSTIC TROUBLE CODES
Required Special Tools
- MB991958: Scan Tool (M.U.T.-III Sub Assembly) MB991824: Vehicles Communication Interface (V.C.I.) MB991827: M.U.T.-III USB Cable MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
| CAUTION | To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. |
Note. If the battery voltage is low, diagnostic trouble codes will not be set. Check the battery if scan tool MB991958 does not display.
- Connect the scan tool MB991958 to the data link connector.
- Turn the ignition switch to the "ON" position.
- Select "System select" from the start-up screen.
- Select "From 2006 MY" of "Model Year." When the "Vehicle Information" is displayed, check the contents.
- Select "Air Conditioner" from "System List", and press the "OK" button. NOTE: When the "Loading Option Setup" list is displayed, check the applicable item.
- Select "Diagnostic Trouble Code" to read the DTC.
- If a DTC is set, it is shown.
- Choose "Erase DTCs" to erase the DTC.
HOW TO PERFORM ACTUATOR TEST
Required Special Tools
- MB991958: Scan Tool (M.U.T.-III Sub Assembly) MB991824: Vehicles Communication Interface (V.C.I.) MB991827: M.U.T.-III USB Cable MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
| CAUTION | To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. |
- Connect the scan tool MB991958 to the data link connector.
- Turn the ignition switch to the "ON" position.
- Select "System select" from the start-up screen.
- Select "From 2006 MY" of "Model Year." When the "Vehicle Information" is displayed, check the contents.
- Select "Air Conditioner" from "System List", and press the "OK" button. NOTE: When the "Loading Option Setup" list is displayed, check the applicable item.
- Select "Actuator Test."
- Choose an appropriate item and select the "OK" button.
HOW TO DIAGNOSE THE CAN BUS LINE
Required Special Tools
- MB991958: Scan Tool (M.U.T.-III Sub Assembly) MB991824: Vehicles Communication Interface (V.C.I.) MB991827: M.U.T.-III USB Cable MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
| CAUTION | To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. |
- Connect scan tool MB991958 to the data link connector.
- Turn the ignition switch to the "ON" position.
- Select "CAN bus diagnosis" from the start-up screen.
- When the vehicle information is displayed, confirm that it matches the vehicle whose CAN bus lines will be diagnosed. If they match, go to Step 8 . If not, go to Step 5.
- Select "view vehicle information" button.
- When the vehicle information is displayed, confirm again that it matches the vehicle which is being diagnosed. If they match, go to Step 8. If not, go to Step 5 .
- Press the "OK" button.
- When the options are displayed, choose the options (mark the check) and then select "OK".
DIAGNOSTIC TROUBLE CODE CHART
| CAUTION | During diagnosis, a DTC code associated with another system may be set when the ignition switch is turned on with connector(s) disconnected. After completing the repair, confirm all systems for DTC code(s). If DTC code(s) are set, erase them all. |
| Diagnostic trouble code No. | Diagnostic item | Reference |
|---|---|---|
| B10C0 | Interior temperature sensor system (short circuit) | |
| B10C1 | Interior temperature sensor system (open circuit) | |
| B1000 | Control panel communication error | Refer to DIAGNOSTIC TROUBLE CODE CHART |
| B1003 | Mode dial SW error | |
| B1018 | Temperature control dial SW error | |
| B1021 | Fan dial SW error | |
| B1031 | Air thermo sensor system (short circuit) | |
| B1032 | Air thermo sensor system (open circuit) | |
| B1034 | Ambient air temperature sensor system (short circuit) | |
| B1035 | Ambient air temperature sensor system (open circuit) | |
| B1079 | Refrigerant leaks | |
| B2214 | Control panel failure | |
| B223B | Control panel improperly assembled | |
| U1415 | Coding not completed | |
| U0019 | Bus off (CAN1) | |
| U0141 | ETACS-ECU time-out | |
| U0151 | SRS-ECU time-out | |
| U0154 | Occupant classification-ECU time-out | |
| U0155 | Combination meter time-out | |
| U0168 | WCM time-out | |
| U0184 | Audio time-out | |
| U0195 | Satellite radio tuner time-out | |
| U0197 | Hands free module time-out | |
| *: This diagnostic trouble code will be set even if the system is normal. | ||
DIAGNOSTIC TROUBLE CODE CHART
Scheme 2
DTC SET CONDITION
- DTC B10C0 is set if there is a short circuit in the interior temperature sensor input circuit.
- DTC B10C1 is set if there is a defective connector connection, or if there is an open circuit in the harness.
Current trouble
- The A/C-ECU, the interior temperature sensor, or connector(s) or wiring between the two may be defective.
Past trouble
- If DTC B10C0 or B10C1 is stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) between the A/C-ECU and the interior temperature sensor. If the connectors and wiring are normal, and obviously the ECU is the cause of the trouble, replace the ECU. If in doubt, do not replace the ECU.
TROUBLESHOOTING HINT
- Malfunction of connector.
- Malfunction of the harness.
- Malfunction of the interior temperature sensor.
- Malfunction of the A/C-ECU.
DIAGNOSIS
Required Special Tool
- MB991958: Scan Tool (M.U.T.-III Sub Assembly) MB991824: Vehicle Communication Interface (V.C.I.) MB991827: M.U.T.-III USB Cable MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
Scheme 3
- STEP 1. Using scan tool MB991958, diagnose the CAN bus line. CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. Use scan tool MB991958 to diagnose the CAN bus lines. Connect scan tool MB991958. Refer to " «HOW TO CONNECT THE SCAN TOOL (M.U.T.-III)»(ref-394962-S23924378092011040900000) ." Turn the ignition switch to "ON" position. Diagnose the CAN bus line. Q: Is the check result satisfactory? YES: Go to Step 2. NO: Repair the CAN bus lines. Repair the CAN bus lines (Refer to «CAN BUS DIAGNOSTIC CHART»(ref-394933-S26474456552011040900000) ).
- STEP 2. Recheck for diagnostic trouble code. Recheck if the DTC is set. Erase the DTC. Turn the ignition switch to "ON" position. Check if the DTC is set. Q: Is the check result satisfactory? YES: It can be assumed that this malfunction is intermittent. Refer to «HOW TO COPE WITH INTERMITTENT MALFUNCTIONS»(ref-394932-S20634559392011040900000) . NO: Go to Step 3.
- STEP 3. Check interior temperature sensor connector C-122 and A/C-ECU connector C-109 for loose, corroded or damaged terminals, or terminals pushed back in the connector. Q: Are interior temperature sensor connector C-122 and A/C-ECU connector C-109 in good condition? YES: Go to Step 4. NO: Repair or replace the connector. Refer to «HARNESS CONNECTOR INSPECTION»(ref-394934-S10458162582011040900000) .
- STEP 4. Check the wiring harness between A/C-ECU connector C-109 (terminals 17 and 19) and interior temperature sensor connector C-122 (terminals 2 and 1). Check the sensor signal line and ground line for open and short circuit. Q: Is the wiring harness between A/C-ECU connector C-109 (terminals 17 and 19) and interior temperature sensor connector C-122 (terminals 2 and 1) in good condition? YES: Go to Step 5. NO: Repair the wiring harness.
- STEP 5. Check the interior temperature sensor. Measure the resistance between connector terminals 1 and 2 under at least two different temperatures. The resistance values should generally match those in the graph. NOTE: The temperature at the check should not exceed the range in the graph. Q: Is the interior temperature sensor in good condition? YES: Replace the A/C-ECU. Then go to Step 6. NO: Replace the interior temperature sensor. Then go to Step 6.
- STEP 6. Recheck for diagnostic trouble code. Check again if the DTC is set. Connect scan tool MB991958 to the data link connector Turn the ignition switch to the "ON" position. Check if the DTC is set. Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the check result satisfactory? YES: The procedure is complete. NO: Return to Step 1 .
SYMPTOM CHART
| CAUTION | During diagnosis, a DTC code associated with another system may be set when the ignition switch is turned on with connector(s) disconnected. On completion, confirm all systems for DTC code(s). If DTC code(s) are set, erase them all. |
| Symptom | Inspection procedure | Reference |
|---|---|---|
| When the A/C is operation, temperature inside the passenger compartment does not decrease (Cool air is not emitted). | 1 | Refer to SYMPTOM CHART |
| Malfunction of the A/C power supply system. | 2 | |
| The compressor does not work. | 3 | |
| Blower fan and motor do not turn. | 4 | |
| Blower air amount cannot be changed. | 5 | |
| Outside/inside air changeover is not possible. | 6 | |
| A/C outlet air temperature does not increase. | 7 | |
| Air outlet vent cannot be changed. | 8 | |
| Rear window defogger does not operate. | 9 | |
| Blower motor power supply system. | 10 |
SYMPTOM CHART
ACTUATOR TEST REFERENCE
| Item No. | Check items | Driven content |
|---|---|---|
| 2 | Idle up request | Idle-up request signal |
| 5 | In/out select damper | The moving position of outside/inside air selection damper motor |
| 6 | Air mix damper motor | The moving position of air mix damper motor |
| 7 | Front blower fan | The amount of blower motor rotation |
| 8 | Air outlet c/o damper | Air outlet changeover damper motor moving position |
| 10 | Condenser fan (1) | The amount of condenser fan rotation |
| 11 | Air conditioning switch (1) | A/C switch selection position |
| 12 | Rear defogger switch | Rear window defogger switch selection position |
| 13 | A/T lock up open request | A/T lock open request signal |
| 14 | PTC heater | |
| (1) When the engine is not running these function do not work. | ||
| (1) | When the engine is not running these function do not work. |
ACTUATOR TEST REFERENCE CHART
Scheme 4
| Terminal No. | Check items | Check conditions | Normal conditions |
|---|---|---|---|
| 1 | Power transistor (DRAIN) | Air volume control dial: Maximum air volume | 0 to 2 V |
| 2 | Power transistor (GATE) | Air volume control dial: Maximum air volume | Battery positive voltage |
| 3 - 8 | |||
| 9 | A/C control panel (input) | ||
| 10 - 12 | |||
| 13 | Battery power supply | Always | Battery positive voltage |
| 14 | Ground | Always | 1 V or less |
| 15 | IG1 power supply | Ignition switch: IG1 | Battery positive voltage |
| 16 | A/C pressure sensor input | Refer to ON-VEHICLE SERVICE . | Refer to ON-VEHICLE SERVICE . |
| 17 | Interior temperature sensor | Sensor probe temperature: 25°C (77°F) (4.0 kohms) | 2.1 to 2.7 V |
| 18 | Photo sensor input | ||
| 19 | Sensor ground | Always | 1 V or less |
| 20 | A/C pressure sensor power supply | Ignition switch: IG2 | 5 V |
| 21 | Air thermo sensor ground | Always | 1 V or less |
| 22 | Air thermo sensor | Sensor probe temperature: 25°C (77°F) (4.0 kohms) | 2.1 to 2.7 V |
| 23 | |||
| 24 | Motor for air outside/inside air circulation switching damper | ||
| 25 | Motor for air outside/inside air circulation switching damper | ||
| 26 | Motor for air outside/inside air circulation switching damper | ||
| 27 | Motor for air outside/inside air circulation switching damper | ||
| 28 | Air mix damper motor | ||
| 29 | Motor power supply | ||
| 30 | Air outlet changeover damper motor | ||
| 31 | Air outlet changeover damper motor | ||
| 32 | Air outlet changeover damper motor | ||
| 33 | Air outlet changeover damper motor | ||
| 34 | Air mix damper motor | ||
| 35 | Air mix damper motor | ||
| 36 | Air mix damper motor |
A/C-ECU TERMINALS REFERENCE CHART