Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step verifies that the HVAC control module is able to command the appropriate actuator through its full range of motion.
- 3: This step verifies the position of the actuators.
- 4: If the actuator does not move at all, the problem is likely to be the drive circuitry within the HVAC control module, the actuator or the wiring harness. If the actuator does move, but not within its full range of motion, the problem is likely to be a mechanical binding of the actuator door or actuator door linkage.
- 6: This step drives the actuator in one position. The actuator shaft will not move if the actuator door is already in the position you are attempting to drive it to.
- 7: This step drives the actuator in the opposite direction.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 2 | Install a scan tool. Turn ON the ignition, with the engine OFF. With the scan tool, command the actuators in both directions. Observe the Temp, Mode and Recirc Door Position parameter. Does the scan tool indicate that the value of the Door parameter changes from the minimum specified value to the maximum specified value? | 0 Counts 255 Counts | Go to Step 3 | Go to Step 4 |
| 3 | With a scan tool, recheck the Actuator Position parameter in the HVAC control module data list. Does the scan tool display correct values? | Go to Diagnostic Aids | Go to Step 8 | |
| 4 | Does the scan tool indicate that the value of the appropriate Door Position parameter changes by more than the specified value? | 0-3 Counts | Go to Step 8 | Go to Step 5 |
| 5 | Test the door control A circuit and the door control B circuit for the following: An open A high resistance A short to ground A short to voltage Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 6 | |
| 6 | Turn OFF the ignition. Disconnect the HVAC control module. Connect a 10-amp fused jumper wire between the door control A circuit of the appropriate actuator and battery positive voltage. Connect a 10-amp fused jumper wire between the door control B circuit of the appropriate actuator and a good ground. Does the actuator shaft rotate? | Go to Step 10 | Go to Step 7 | |
| 7 | Connect a 10-amp fused jumper wire between the door control B circuit of the appropriate actuator and battery positive voltage. Connect a 10-amp fused jumper wire between the door control A circuit of the appropriate actuator and a good ground. Does the actuator shaft rotate? | Go to Step 10 | Go to Step 8 | |
| 8 | Inspect the appropriate air temperature, recirc door or mode door actuator for the following conditions: A misaligned actuator Broken or binding linkages or actuator door An obstruction that prevents the actuator door from operating within its full range of motion Missing seals to the actuator door Misaligned seals to the actuator door Did you find and correct the condition? | Go to Step 13 | Go to Step 9 | |
| 9 | Inspect for poor connections at the harness connector of the appropriate actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 11 | |
| 10 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 12 | |
| 11 | IMPORTANT: Perform the recalibration procedure for the appropriate actuator after the replacement. Upon fuse replacement, a recalibration of the actuator will occur. Replace the appropriate actuator. Air temperature actuator-Refer to Air Temperature Actuator Replacement . Mode actuator-Refer to Mode Actuator Replacement . Recirculation actuator-Refer to Recirculation Actuator Replacement . Did you complete the replacement? | Go to Step 13 | ||
| 12 | Replace the HVAC control module. Refer to Control Module References in for replacement, setup and programming. Did you complete the replacement? | Go to Step 13 | ||
| 13 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 3 | System OK | |
| IMPORTANT |
|---|
| Perform the recalibration procedure for the appropriate actuator after the replacement. Upon fuse replacement, a recalibration of the actuator will occur. |
DTC B0248, B0268 or B0408
The numbers below refer to the step numbers on the diagnostic table.
- 4: This step tests for the proper operation of the circuit in the low voltage range.
- 5: This step tests for the proper operation of the circuit in the high voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to ground.
- 6: This step tests for a short to voltage in the 5-volt reference circuit.
- 7: This step tests for a high resistance or an open in the low reference circuit.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 2 | IMPORTANT: The ambient air temperature must be above 4°C (40°F). Turn OFF the ignition. Inspect the A/C compressor for free rotation operation. Start the engine. Place the HVAC control module in the OFF position. Does the A/C compressor operate? | Go to HVAC Compressor Clutch Does Not Disengage | Go to Step 3 | |
| 3 | Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the A/C Refrigerant Pressure-A/C High Side Pressure parameter in the powertrain control module data list. Does the scan tool indicate that the A/C High Side Pressure parameter is within the specified range? | 0.2-4.9 V 9-453 psi | Go to Diagnostic Aids | Go to Step 4 |
| 4 | Turn OFF the ignition. Disconnect the A/C refrigerant pressure sensor. Turn ON the ignition, with the engine OFF. With a scan tool, observe the A/C Refrigerant Pressure-A/C High Side Pressure parameter in the powertrain control module data list. Does the scan tool indicate that the A/C Refrigerant Pressure parameter is less than the specified value? | 0.2 V 9 psi | Go to Step 5 | Go to Step 11 |
| 5 | Turn OFF the ignition. Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the A/C refrigerant pressure sensor and the signal circuit of the A/C refrigerant pressure sensor. Turn ON the ignition, with the engine OFF. With a scan tool, observe the A/C Refrigerant Pressure-A/C High Side Pressure parameter in the powertrain control module data list. Does the scan tool indicate that the A/C Refrigerant Pressure parameter is greater than the specified value? | 4.9 V 453 psi | Go to Step 6 | Go to Step 9 |
| 6 | Disconnect the fused jumper wire. Measure the voltage between the 5-volt reference circuit of the A/C refrigerant pressure sensor and the low reference circuit of the A/C refrigerant pressure sensor. Does the voltage measure less than the specified value? | 4.9 V 453 psi | Go to Step 7 | Go to Step 8 |
| 7 | Turn OFF the ignition. Disconnect the negative battery cable. Measure the resistance from the low reference circuit of the A/C refrigerant pressure sensor to a good ground. Does the resistance measure less than the specified value? | 5 ohms | Go to Step 13 | Go to Step 12 |
| 8 | Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 14 | |
| 9 | Test the 5-volt reference circuit of the A/C refrigerant pressure sensor for a short to ground, a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 10 | |
| 10 | Test the signal circuit of the A/C refrigerant pressure sensor for a short to ground, a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 14 | |
| 11 | Test the signal circuit of the A/C refrigerant pressure sensor for a short to voltage or ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 14 | |
| 12 | Disconnect the powertrain control module (PCM). Test the low reference circuit of the A/C refrigerant pressure sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 14 | |
| 13 | Inspect for poor connections at the harness connector of the A/C refrigerant pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 15 | |
| 14 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 16 | |
| 15 | Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement . Did you complete the replacement? | Go to Step 17 | ||
| 16 | Replace the PCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 17 | ||
| 17 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 2 | System OK | |
| IMPORTANT |
|---|
| The ambient air temperature must be above 4°C (40°F). |
DTC P0532 or P0533
The numbers below refer to the step numbers on the diagnostic table.
- 2: The A/C compressor relay output is disabled if engine coolant temperature is above 128°C (262°F). The instrument panel engine coolant indicator will indicate overheating.
- 3: Place the mode switch in any position except OFF and place the air temperature control switch in a cold setting. Use the bi-level mode for consistent testing of the A/C system operation.
- 6: The HVAC control module is inoperative if the module does not respond to any operator control requests.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The A/C compressor clutch will not engage if an A/C request has been made and a Powertrain DTC has not been set. | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Start the engine. Observe the instrument panel (I/P) coolant temperature indicator and the driver information center. Is the engine coolant temperature indicator indicating an over heat status or is the driver information center indicating low coolant? | Go to Engine Overheating | Go to Step 3 |
| 3 | IMPORTANT: For A/C compressor operation, the ambient air temperature must be above 4°C (40°F). Start the engine. Place the blower motor switch in the maximum speed position. Place the A/C request switch in the ON position. Place the air temperature switch in the coldest position. Does the A/C compressor clutch engage? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 4 |
| 4 | Open the window in order to ventilate the interior of the vehicle. If the A/C system was operating, then wait for approximately 2 minutes. Turn OFF the ignition. Install the J 43600 ACR 2000 Air Conditioning Service Center. Record the ambient air temperature at the vehicle. Record readings of the low and high side STATIC pressures. Compare the low side pressure values and the high side pressure values with the allowable limits for the recorded ambient air temperature. Refer to Air Conditioning (A/C) System Performance Test . Are the pressure values within the allowable limits for the recorded ambient air temperature and within 103 kPa (15 psi) of each other? | Go to Step 5 | Go to Leak Testing |
| 5 | Turn ON the ignition, with the engine OFF. With a scan tool, observe the A/C High Side Pressure Sensor parameter in the powertrain control module data list. Compare the scan tool A/C High Side Pressure parameter to the high side pressure values on the J 43600 . Are the high side pressure values within 103 kPa (15 psi) of each other? | Go to Step 6 | Go to Step 23 |
| 6 | Is the HVAC control module inoperative? | Go to Step 16 | Go to Step 7 |
| 7 | Start the engine. With a scan tool, observe the A/C Request Signal parameter in the powertrain control module (PCM) data list. Place the air temperature switch in the coldest position. Place the A/C request switch in the ON position. Does the scan tool indicate that the A/C Request Signal parameter is YES? | Go to Step 10 | Go to Step 8 |
| 8 | Start the engine. With a scan tool, observe the A/C Switch parameter in the body control module (BCM) data list. Place the air temperature switch in the coldest position. Place the A/C request switch in the ON position. Does the scan tool indicate that the A/C Switch parameter is ON? | Go to Step 9 | Go to Step 18 |
| 9 | Turn OFF the ignition. Test the A/C request signal circuit for a short to voltage, for a high resistance or for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 10 |
| 10 | With a scan tool, command the A/C compressor clutch relay ON and OFF. Does the clutch relay turn ON and OFF with each command? | Go to Step 14 | Go to Step 11 |
| 11 | Turn OFF the ignition. Disconnect the A/C compressor clutch relay. Turn ON the ignition, with the engine OFF. Probe the coil side of the voltage supply circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 12 | Go to Step 26 |
| 12 | Connect a test lamp between the control circuit and the coil side of the voltage supply circuit. With a scan tool, command the A/C compressor clutch relay ON and OFF. Does the test lamp turn ON and OFF with each command? | Go to Step 28 | Go to Step 13 |
| 13 | Does the test lamp remain illuminated with each command? | Go to Step 21 | Go to Step 20 |
| 14 | Turn OFF the ignition. Disconnect the A/C compressor clutch relay. Probe the switch side of the voltage supply circuit with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 15 | Go to Step 25 |
| 15 | Connect a 10-amp fused jumper between the switch side voltage circuit of the clutch relay and the supply voltage circuit of the clutch. Turn ON the ignition, with the engine OFF. Does the A/C compressor clutch engage? | Go to Step 28 | Go to Step 22 |
| 16 | Test the ignition 3 voltage circuit of the HVAC control module for a short to ground, for a high resistance or for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 17 |
| 17 | Test the ground circuit of the HVAC control module for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 30 |
| 18 | Start the engine. Place the A/C request in the ON position. Measure the voltage on the request circuit at the BCM to a good ground. Does the value measure near battery voltage? | Go to Step 31 | Go to Step 19 |
| 19 | Test the A/C request signal circuit for a high resistance, open or a short to ground. Refer to Circuit Testing and to Wiring Repairs . Did you complete the repair? | Go to Step 39 | Go to Step 30 |
| 20 | Test the control circuit of the A/C compressor clutch relay for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 32 |
| 21 | Test the control circuit of the A/C compressor clutch relay for a short to ground. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 32 |
| 22 | Test the supply voltage circuit at the A/C compressor clutch for a short to ground, for a high resistance or for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 24 |
| 23 | Test the ground circuit of the A/C refrigerant pressure sensor for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 27 |
| 24 | Test the ground circuit of the A/C compressor clutch for a high resistance or for an open. Refer to Circuit Testing and to Wiring Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 29 |
| 25 | Repair the switch side voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 39 | |
| 26 | Repair the coil side of the voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 39 | |
| 27 | Inspect for poor connections at the harness connector of the A/C high pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 33 |
| 28 | Inspect for poor connections at the A/C compressor clutch relay. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 34 |
| 29 | Inspect for poor connections at the harness connector of the A/C compressor clutch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 35 |
| 30 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 36 |
| 31 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 37 |
| 32 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs . Did you find and correct the condition? | Go to Step 39 | Go to Step 38 |
| 33 | Replace the A/C refrigerant pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement . Did you complete the replacement? | Go to Step 39 | |
| 34 | Replace the A/C compressor clutch relay. Did you complete the replacement? | Go to Step 39 | |
| 35 | Replace the A/C compressor clutch assembly. Refer to Compressor Clutch Assembly Replacement . Did you complete the replacement? | Go to Step 39 | |
| 36 | Replace the HVAC control module. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 39 | |
| 37 | Replace the BCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 39 | |
| 38 | Replace the PCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 39 | |
| 39 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 4 |
| IMPORTANT |
|---|
| For A/C compressor operation, the ambient air temperature must be above 4°C (40°F). |
HVAC Compressor Clutch Does Not Engage
The numbers below refer to the step numbers on the diagnostic table.
- 2: This test resets HVAC control module and checks for current air temperature actuator DTC.
- 7: Ambient air temperature must be above 3°C (38°F) in order for this A/C Compressor test to be run.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The temperature cannot be adjusted or cooling is insufficient during the A/C operation. | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 2 | Install a scan tool. Turn ON the ignition, with the engine OFF. Recalibrate the motors. Refer to Re-Calibrating Actuators . With a scan tool, observe the current Diagnostic Trouble Code List. Refer to Diagnostic Trouble Code (DTC) List - Vehicle Does the scan tool display DTCs? | Go to Diagnostic System Check - Vehicle | Go to Step 3 | |
| 3 | Place the blower motor switch in each speed position. Does the blower motor operate in any speed position? | Go to Step 4 | Go to Blower Motor Inoperative | |
| 4 | Does the blower motor operate in each speed position? | Go to Step 5 | Go to Blower Motor Malfunction | |
| 5 | Place the blower motor switch in the maximum speed position. Place the mode controls in the bi-level position. Alternately, place the recirculation switch in the outside air and recirculation positions. Does the recirculation door move from the recirculation position to the ambient air position? | Go to Step 6 | Go to Air Recirculation Malfunction | |
| 6 | Place the passenger temperature in the OFF position. Does the Too Hot in Vehicle concern occur when A/C cooling desired? | Go to Step 7 | Go to Step 9 | |
| 7 | IMPORTANT: Ambient air temperature must be above 3°C (38°F). Cover the Ambient light sensor. Start the engine. Open all panel outlets in order to allow maximum air flow. Place the air temperature switch to the coldest position. Place the mode switch in the vent position. Place the blower motor switch in the maximum speed position. Does the A/C compressor operate? | Go to Step 8 | Go to HVAC Compressor Clutch Does Not Engage | |
| 8 | Perform the A/C system performance test. Refer to Air Conditioning (A/C) System Performance Test . Did you find and correct the condition? | Go to Step 24 | Go to Step 9 | |
| 9 | Inspect the upper and lower air temperature sensors for the following conditions: An obstruction to the airflow A damaged or a missing seal to the sensor Misaligned air ducts A misaligned sensor Did you find and correct the condition? | Go to Step 24 | Go to Step 10 | |
| 10 | Turn ON the ignition, with the engine OFF. Inspect for airflow through the inside air temperature assembly by placing a 5-cm (2-in) square piece of paper over the sensor air inlet. Does the paper stay in place? | Go to Step 11 | Go to Step 14 | |
| 11 | Install a thermometer near the upper and lower air sensors and the inside air temperature assembly. With a scan tool, observe the following data parameters in the HVAC Data list: Upper AC Duct Temp. Lower Htr. Duct Temp. Inside Air Temp. For the upper and lower duct temp parameter conversion from counts to temp refer to Sensor Resistance Table .Does the scan tool indicate that the sensor temperatures are within the specifications at the thermometer temperatures? | 3 to +3°C (-5 to +5°F) | Go to Step 12 | Go to Step 17 |
| 12 | Turn the engine OFF. Install a scan tool. Cover the sunload sensor. Start the engine. Place the driver side temperature at 22°C (72°F). With a scan tool, observe the Sunload Sensor data parameter in the HVAC control module sensor data list. Does the scan tool indicate that the Sunload sensor parameter is greater than the specified value? | 224 Counts | Go to Step 13 | Go to Step 19 |
| 13 | Uncover the sunload sensor. Direct a light source at the sunload sensor. Do the counts change? | Go to Step 24 | Go to Step 19 | |
| 14 | Test the Ignition 3 voltage circuit of the HVAC control module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 15 | |
| 15 | Test the battery positive voltage circuit of the HVAC control module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 16 | |
| 16 | Test the ground circuit of the HVAC control module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 20 | |
| 17 | Test the suspect temperature sensor resistance. Refer to Sensor Resistance Table . Does the resistance measure near the Sensor Resistance Table? | Go to Step 20 | Go to Step 18 | |
| 18 | Inspect for poor connections at the harness connector of the suspect air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 21 | |
| 19 | Inspect for poor connections at the harness connector of the sunload sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 22 | |
| 20 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 23 | |
| 21 | Replace the appropriate temperature sensor. Refer to the following procedures: Air Temperature Sensor Replacement - Upper Air Temperature Sensor Replacement - Lower Did you complete the replacement? | Go to Step 24 | ||
| 22 | Replace the ambient light sensor. Refer to Ambient Light Sensor Replacement . Did you complete the replacement? | Go to Step 24 | ||
| 23 | Replace the HVAC control module. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 24 | ||
| 24 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 | |
| IMPORTANT |
|---|
| Ambient air temperature must be above 3°C (38°F). |
Too Hot in Vehicle
- 2: This test resets HVAC control module and checks for current air temperature actuator DTC.
- 8: This checks for proper operation of coolant system to ensure heater output.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The temperature cannot be adjusted or the heating is insufficient. | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 2 | Install a scan tool. Turn ON the ignition, with the engine OFF. Recalibrate the motors. Refer to Re-Calibrating Actuators . With a scan tool, observe the current Diagnostic Trouble Code List. Refer to Diagnostic Trouble Code (DTC) List - Vehicle . Does the scan tool display DTCs? | Go to Diagnostic System Check - Vehicle | Go to Step 3 | |
| 3 | Place the blower motor switch in each speed position. Does the blower motor operate in any speed position? | Go to Step 4 | Go to Blower Motor Inoperative | |
| 4 | Does the blower motor operate at the desired speeds? | Go to Step 5 | Go to Blower Motor Malfunction | |
| 5 | Place the blower motor switch in the maximum speed position. Place the mode controls in the bi-level position. Alternately, place the recirculation switch in the outside air and recirculation positions. Does the recirculation door move from the recirculation position to the ambient air position? | Go to Step 6 | Go to Air Recirculation Malfunction | |
| 6 | Does the Too Cold in Vehicle concern occur when heating or defrosting is desired? | Go to Step 7 | Go to Step 9 | |
| 7 | Start the engine. Place the HVAC control module in the OFF position. Does the A/C compressor operate? | Go to HVAC Compressor Clutch Does Not Disengage | Go to Step 8 | |
| 8 | Inspect the cooling system for the following conditions: A low coolant level A loose or worn accessory drive belt A leaking radiator hose or heater hose A kinked radiator hose or heater hose A missing radiator cap pressure seal A leaking radiator cap Did you find and correct the condition? | Go to Step 24 | Go to Step 9 | |
| 9 | Inspect the upper and lower air temperature sensors for the following conditions: An obstruction to the airflow A damaged or a missing seal in the sensor Misaligned air ducts A misaligned sensor Did you find and correct the condition? | Go to Step 24 | Go to Step 10 | |
| 10 | Turn ON the ignition, with the engine OFF. Inspect for airflow through the inside air temperature assembly by placing a 5-cm (2-in) square piece of paper over the sensor air inlet. Does the paper stay in place? | Go to Step 11 | Go to Step 14 | |
| 11 | Install a thermometer near the upper and lower air sensors and the inside air temperature assembly. With a scan tool, observe the following data parameters in the HVAC Sensor data list: Upper AC Duct Temp. Lower Htr. Duct Temp. Inside Air Temp. For the upper and lower duct temp parameter conversion from counts to temp, refer to Sensor Resistance Table .Does the scan tool indicate that the sensor temperatures are within the specification at the thermometer temperatures? | 3 to +3°C (-5 to +5°F) | Go to Step 12 | Go to Step 17 |
| 12 | Turn the engine OFF. Install a scan tool. Cover the sunload sensor. Start the engine. Place the temperature to 22°C (72°F). With a scan tool, observe the Sunload Sensor data parameter in the HVAC control module sensor data list. Does the scan tool indicate that the sunload sensor parameter is greater than the specified value? | 224 Counts | Go to Step 13 | Go to Step 19 |
| 13 | Uncover the sunload sensor. Direct a light source at the sunload sensor. Do the counts change? | System OK | Go to Step 19 | |
| 14 | Test the ignition 3 voltage circuit of the HVAC control module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 15 | |
| 15 | Test the battery positive voltage circuit of the HVAC control module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 16 | |
| 16 | Test the ground circuit of the HVAC control module for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 20 | |
| 17 | Test the suspect temperature sensor resistance. Refer to Sensor Resistance Table . Does the resistance measure near the Sensor Resistance Table? | Go to Step 20 | Go to Step 18 | |
| 18 | Inspect for poor connections at the harness connector of the suspect air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 21 | |
| 19 | Inspect for poor connections at the harness connector of the sunload sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 22 | |
| 20 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 24 | Go to Step 23 | |
| 21 | Replace the appropriate temperature sensor. Refer to the following procedures: Air Temperature Sensor Replacement - Upper Air Temperature Sensor Replacement - Lower Did you complete the replacement? | Go to Step 24 | ||
| 22 | Replace the ambient light sensor. Refer to Ambient Light Sensor Replacement . Did you complete the replacement? | Go to Step 24 | ||
| 23 | Replace the HVAC control module. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 24 | ||
| 24 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 | |
Too Cold in Vehicle
The number below refers to the step number on the diagnostic table.
- 4: This step drives the actuator in both directions. If the actuator door is already in the position you are attempting to drive it to, reverse the polarity to drive the actuator in opposite direction.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: Air recirculation is inoperative or is always ON. | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Turn ON the ignition, with the engine OFF. Observe the Recirculation and Outside Air Switch. Activate the Recirculation and Outside Air switches. Does the Recirculation and Outside Air Switch change states? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
| 3 | Test the recirculation door control A circuit and the recirculation door control B circuit for the following: An open A high resistance A short to ground A short to voltage Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 4 |
| 4 | Turn OFF the ignition. Disconnect the HVAC control module. Connect a 10-amp fused jumper wire between the actuator door control A circuit of the recirculation actuator and battery positive voltage. Connect a 10-amp fused jumper wire between the actuator door control B circuit of the recirculation actuator and a good ground. Reverse the polarity between the recirculation actuator control A and B circuits. Does the actuator shaft rotate in both directions? | Go to Step 5 | Go to Step 6 |
| 5 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 6 | Inspect for poor connections at the harness connector of the recirculation actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 7 | Replace the recirculation actuator. Refer to Recirculation Actuator Replacement . Did you complete the replacement? | Go to Step 9 | |
| 8 | Replace the HVAC control module. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 9 | |
| 9 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
Air Recirculation Malfunction
Air Delivery Description and Operation
The air delivery controls are divided into 4 areas
- HVAC control components
- Air speed
- Air distribution
- Recirculation operation
- Automatic operation
Recirculation Operation
The HVAC control module controls the air intake through the recirculation actuator. Recirculation is not available when the mode is in bi-level through defrost. The operator must activate the blower for Recirculation operation.
Automatic Operation
In automatic operation, the HVAC control module will maintain the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, mode actuator and recirculation.
To place the HVAC system in automatic mode, the following is required
- The blower motor switch must be in the AUTO position.
- The air temperature switch must be in any other position other than 60 or 90 degrees.
- The mode switch must be in the AUTO position.
Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators will automatically adjust to maintain the temperature selected. The HVAC control module performs the following functions to maintain the desired air temperature
- Regulate blower motor speed
- Position the air temperature actuator
- Position the mode actuator
- Position the recirculation actuator
- Request A/C operation
When the warmest position is selected in automatic operation the blower speed will increase gradually until the vehicle reaches normal operating temperature. When normal operating temperature is reached the blower will stay on high speed and the air temperature actuators will stay in the full heat position. When the coldest position is selected in automatic operation the blower will stay on high and the air temperature actuators will stay in the full cold position.
In cold temperatures, the automatic HVAC system will provide heat in the most efficient manner. The vehicle operator can select an extreme temperature setting but the system will not warm the vehicle any faster. In warm temperatures, the automatic HVAC system will also provide air conditioning in the most efficient manner. Selecting an extreme cool temperature will not cool the vehicle any faster.
Remote Vehicle Start HVAC Operation
The HVAC preset RVS settings are as follows
- Inside air temperature input below 22°C (72°F) the HVAC system will set the blower motor speed to high speed, set the mode door to the defrost position, set the temperature door to the full hot position and set the recirculation door to the outside air position.
- Inside air temperature input above 26°C (79°F) the HVAC system will set the blower motor speed to high speed, set the mode door to the panel position, set the temperature door to the full cold position, request A/C compressor operation and set the recirculation door to the recirculate position.
- Inside air temperature input between 22°C (72°F) and 26°C (79°F) the HVAC system will set the blower motor speed to a medium speed, set the mode door to the panel position, set the temperature door to the full cold position, request A/C compressor operation and set the recirculation door to the outside air position.
When you transition from remote start to normal operation (by entering car, inserting key and turning on) the C68 control head reverts to the prior remote start function settings.
Air Temperature Description and Operation
The air temperature controls are divided into 4 primary areas
- Radio - Driver Information Center (DIC)
- Automatic operation
- The Heating and Air Conditioning System
- The A/C cycle
Heating and A/C Operation
The purpose of the heating and A/C system is to provide the following
- Heated air
- Cooled air
- Remove humidity from the interior of the vehicle
- Reduce windshield fogging
Regardless of the temperature setting, the following can effect the rate that the HVAC system can achieve a desired temperature
- Recirculation actuator setting
- Difference between inside and desired temperature
- Difference between ambient and desired temperature
- Blower motor speed setting
- Mode setting
The HVAC control module commands or monitors the following actions when an air temperature setting is selected
- Warmest position-The air temperature actuator door position directs maximum air flow through the heater core.
- Coldest position-The air temperature actuator door position directs maximum air flow around the heater core.
- Between the warmest and coldest position-The following sensors are monitored to direct the appropriate amount of air through the heater core to achieve the desired temperature: Sunload Ambient temperature Inside temperature Lower duct temperature Upper duct temperature
The A/C system is engaged by selecting the A/C or auto switches for the blower motor and the mode switch on the HVAC control module. The HVAC control module sends a A/C request message to the body control module (BCM) which sends a class 2 message to the powertrain control module (PCM) or engine control module (ECM) for A/C compressor clutch operation. The following conditions must be met in order for the PCM or ECM to turn on the compressor clutch
- HVAC control module Evaporator temperature is more than 4°C (39°F). The control module operating range is 9-16 volts.
- BCM Battery voltage between 9-16 volts A/C request from the HVAC control module
- PCM or ECM Engine coolant temperature (ECT) is less than 114°C (237°F). Engine RPM is between 0-5,000 RPM. A/C pressure is between 248-2997 kPa (36-435 psi).
Once engaged, the compressor clutch will be disengaged for the following conditions
- Throttle position is 100 percent.
- A/C pressure is more than 2997 kPa (435 psi).
- A/C pressure is less than 248 kPa (36 psi).
- ECT is more than 120°C (248°F).
- Engine speed is more than 5,000 RPM.
- Transmission shift
- The PCM or ECM detects excessive torque load.
- The PCM or ECM detects insufficient idle quality.
- The PCM or ECM detects a hard launch condition.
When the compressor clutch disengages, the compressor clutch diode protects the electrical system from a voltage spike.
In automatic operation, the HVAC control module will maintain the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, mode actuator and recirculation.
To place the HVAC system in automatic mode, the following is required
- The blower motor switch must be in the AUTO position.
- The air temperature switch must be in any other position other than 60 or 90 degrees.
- The mode switch must be in the AUTO position.
Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators will automatically adjust to maintain the temperature selected. The HVAC control module performs the following functions to maintain the desired air temperature
- Regulate blower motor speed
- Position the air temperature actuator
- Position the mode actuator
- Position the recirculation actuator
- Request A/C operation
When the warmest position is selected in automatic operation the blower speed will increase gradually until the vehicle reaches normal operating temperature. When normal operating temperature is reached the blower will stay on high speed and the air temperature actuators will stay in the full heat position. When the coldest position is selected in automatic operation the blower will stay on high and the air temperature actuators will stay in the full cold position.
In cold temperatures, the automatic HVAC system will provide heat in the most efficient manner. The vehicle operator can select an extreme temperature setting but the system will not warm the vehicle any faster. In warm temperatures, the automatic HVAC system will also provide air conditioning in the most efficient manner. Selecting an extreme cool temperature will not cool the vehicle any faster.
The HVAC preset RVS settings are as follows
- Inside air temperature input below 22°C (72°F) the HVAC system will set the blower motor speed to high speed, set the mode door to the defrost position, set the temperature door to the full hot position and set the recirculation door to the outside air position.
- Inside air temperature input above 26°C (79°F) the HVAC system will set the blower motor speed to high speed, set the mode door to the panel position, set the temperature door to the full cold position, request A/C compressor operation and set the recirculation door to the recirculate position.
- Inside air temperature input between 22°C (72°F) and 26°C (79°F) the HVAC system will set the blower motor speed to a medium speed, set the mode door to the panel position, set the temperature door to the full cold position, request A/C compressor operation and set the recirculation door to the recirc air position.
When you transition from remote start to normal operation (by entering car, inserting key and turning on) the HVAC control head reverts to the prior remote start function settings.