HVAC System - Automatic Chevrolet Malibu VII

Fastener Tightening Specifications

Sensor Resistance Table (Inside Air Temperature Sensor)

Sensor Resistance Table (Upper and Lower Duct Temp Sensors)

Sensor Resistance Table (Duct Temp conversion temp to counts)

Sensor Resistance Table (Ambient Air Temp Sensor)

The Tech 2 will display sensor value as a voltage. This gives the approximate voltage expected at different ambient temperatures as well as what should be read with an ohmmeter connected to the sensor. Since this is raw data any heat from underhood that changes ambient temp around the sensor might skew the reading, so let the engine compartment cool.

Scheme 43

Scheme 44

Scheme 45

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The body control module (BCM) monitors the ambient air temperature sensor to display ambient air temperature. The temperature sensor is a 2-wire negative temperature co-efficient thermistor. The BCM applies 5 volts to an internal input resistor that is connected to the signal circuits of the ambient air temperature sensor. The BCM provides the ground to the ambient air temperature sensor through the low reference circuit. The BCM monitors the voltage drop across the ambient air temperature sensor and uses the input for automatic control calculations. When the ambient air temperatures are cold, the resistance of the sensor is high and the voltage signals are high. When the ambient air temperatures are hot, the resistance of the sensors is low and the voltage signals are low. The BCM converts the voltage value to a temperature value of Celsius and Fahrenheit that will be displayed by the driver information center (DIC).

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

1. The BCM detects the sensor signal circuit is less than 0.05 volt.
2. The BCM detects the sensor signal circuit is greater than 4.9 volts.

Action Taken When the DTC Sets

1. The default value of 85°C (185°F) will be substituted for the ambient air temperature sensor data by the HVAC control module.
2. The DIC will display actual temperature.

Conditions for Clearing the DTC

1. The DTC will become history if the BCM no longer detects a failure.
2. The history DTC will clear after 100 fault-free ignition cycles.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
2. «Air Delivery Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool HVAC Control Module Ambient Air Temp Sensor parameter. The reading should be between -35 and 85°C (-39 and +185°F) and change with air temperature changes.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ambient air temperature sensor.
2. Ignition OFF, test for less than 10 ohms between the following low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
3. Ignition ON, verify the scan tool BCM Ambient Air Temp Sensor parameter is greater than 4.8 volts. If less than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool BCM Air Temp Sensor parameter is less than 0.20 volt. If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the ambient air temperature sensor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Ambient Air Temperature Sensor Replacement»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
2. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Inside Air Temperature Sensor

The inside air temperature sensor is internal to the HVAC control module.

Upper and Lower Air Duct Temperature Sensors

The HVAC control module supplies the air duct temperature sensors with a low reference circuit and 5-volt signal circuit. The HVAC control module determines the voltage drop across the sensor, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases and the voltage signal decreases. As the air temperature decreases, the sensor resistance increases and the voltage signal increases.

Ignition ON.

The HVAC control module detects the air temperature sensor signal circuit is less than 5 counts or greater than 250 counts.

The Auto feature of the HVAC control module will be inoperative.

1. The DTC will become history if the HVAC control module no longer detects a failure.
2. The history DTC will clear after 100 fault-free ignition cycles.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
2. «Air Delivery Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

B1063

Verify DTC B1063 is not set.

1. If the DTC is set, replace the HVAC control module.

B0173 or B0178

Ignition ON, observe the appropriate scan tool Duct Air Temp. Sensor parameter. The reading should be between 5-250 counts and change with inside passenger compartment or upper or lower air duct air temperature changes.

1. Ignition OFF, disconnect the harness connector at the appropriate air duct temperature sensor.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
3. Ignition ON, verify that both the appropriate scan tool Duct Air Temp. Sensor parameter is less than 5 counts. If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the appropriate scan tool Duct Air Temp. Sensor parameter is greater than 250 counts. If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
5. If all circuits test normal, test or replace the appropriate air temperature sensor.

Component Testing

1. A thermometer can be used to test the sensor off the vehicle in warm and or cold water. Refer to «Sensor Resistance Table (Inside Air Temperature Sensor)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table-inside-air-temperature) or «Sensor Resistance Table (Upper and Lower Duct Temp Sensors)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table-upper-and-lower) or «Sensor Resistance Table (Duct Temp conversion temp to counts)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table-duct-temp-conversion) or «Sensor Resistance Table (Ambient Air Temp Sensor)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table-ambient-air-temp) for this test.
2. Test the ambient air temperature sensor by varying the sensor temperature while monitoring the sensor resistance.
3. Compare the readings with the Temperature vs Resistance table and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Duct Air Temperature Sensor Replacement - Upper»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
2. «Duct Air Temperature Sensor Replacement - Lower»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
3. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit Description

The sunload sensor is a 2-wire photo diode. The vehicle uses a single sunload sensor. The sensor is integrated into the sunload sensor assembly along with the ambient light sensor. Body ground and signal circuits enable the sensor to operate. As the sunload increases, the sensor signal decreases. The sensor operates within an intensity range between completely dark and very bright. The sensor signal varies between 0-5 volts. The body control module (BCM) converts the signal to a range between 0-255 counts. The sunload sensor provides the HVAC control module with a measurement of the amount of light shining on the vehicle. Bright or high intensity light causes the vehicles interior temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle.

Ignition ON.

The BCM detects the signal circuit is less than 0.09 volt (5 counts) or greater than 4.90 volts (250 counts).

The HVAC control module will operate the system as if no sunload condition exists.

1. The DTC will become history if the BCM no longer detects the condition that set the DTC.
2. The history DTC will clear after 50 fault-free ignition cycles.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
2. «Air Delivery Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Sunload Sensor parameter. The reading should be between 5-250 counts and change with sunlight changes.

1. Ignition OFF, disconnect the harness connector at the sunload sensor.
2. Test for less than 10 ohms between the ground circuit terminal C and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, test for 4.8-5.2 volts between the ground circuit terminal C and the signal circuit terminal A. If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the BCM. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, test or replace the sunload sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Ambient Light Sensor Replacement»(/chevrolet/malibu/vii-2008-2012/remont/exterior-lights/#lighting-system)
2. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM and HVAC control module replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The actuators operate using 5 circuits. A 5-volt reference, low reference, signal circuit and two bi-directional 0 or 12 volt control circuits. The HVAC control module supplies a low reference and 5-volt reference to the potentiometer. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. As the actuator door changes position the door position signal circuit voltage also changes. The two bi-directional control circuits enable the actuator to operate. Both circuits are set to 0 volts when the HVAC control module detects, from the feedback potentiometer, that the actuator is in the desired position. In order to move the actuator, the HVAC control module switches the appropriate control circuit to 12 volts.

1. DTC B0248 is for the mode actuator.
2. DTC B0268 is for the recirculate actuator.
3. DTC B0408 is for the air temperature actuator.

1. Ignition ON.
2. Ignition voltage is between 9-16 volts.
3. The HVAC module is ON.

The actual door position differs from the commanded door position by more than 4 counts or the HVAC control module detects the door position signal circuit is less than 7 counts or greater than 250 counts.

Driver A and driver B circuits are deactivated for the appropriate actuator.

1. The DTC becomes history when the HVAC control module no longer detects the condition that set the DTC.
2. The history DTC will clear after 100 fault-free ignition cycles.
3. The DTC can be cleared with a scan tool.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)
2. «Air Delivery Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the appropriate actuator in both directions with a scan tool. The scan tool Door Position parameter reading should be between 5 and 250 counts.

1. Ignition OFF, disconnect the harness connector at the appropriate actuator.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 10 and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 8 and ground. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.
4. Verify the appropriate scan tool Door Position parameter is greater than 250 counts. If less than the specified range, test the signal circuit terminal 9 for a short to ground. If the circuit tests normal, replace the HVAC control module.
5. Install a 3A fused jumper wire between the signal circuit terminal 9 and the low reference circuit terminal 10. Verify the appropriate scan tool Door Position parameter is less than 3 counts. If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
6. Ignition OFF, test for less than 10 ohms between the control circuit terminal 6 and ground. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the HVAC control module.
7. Ignition OFF, test for less than 10 ohms between the control circuit terminal 5 and ground. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If circuit tests normal, replace the HVAC control module.
8. Connect a test lamp between control circuit terminal 5 and control circuit terminal 6.
9. Command the appropriate actuator door in both directions with a scan tool. The test lamp should turn ON and OFF when commanded in both directions. If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, replace the HVAC control module.
10. If both circuits test normal, test or replace the actuator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Air Inlet Valve Actuator Replacement»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
2. «Mode Valve Actuator Replacement»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
3. «Temperature Valve Actuator Replacement»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
4. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. The ECM supplies a 5-volt reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the A/C refrigerant pressure sensor signal to the ECM to vary. When the pressure is low, the signal voltage is low. When the pressure is high, the ECM commands the cooling fans on. When pressure is too high or too low, the ECM will not allow the A/C compressor clutch to engage.

1. The engine is running.
2. The battery voltage is between 11-18 volts.

1. The ECM detects that the A/C pressure is less than 9 psi (0.02 volt).
2. The ECM detects that the A/C pressure is more than 453 psi (4.90 volts).

1. The ECM will not illuminate the malfunction indicator lamp (MIL).
2. The ECM stores the failure records.
3. The A/C compressor clutch is disabled.

1. The history DTC will clear after 40 consecutive ignition cycles have occurred without a malfunction.
2. The DTC or DTCs can be cleared by using the scan tool.
3. The DTC will become history if the ECM no longer detects a failure.

Diagnostic Aids

A malfunction within the refrigerant system causing high pressure can cause this DTC to set.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Air Delivery Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)
2. «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool A/C High Side Pressure parameter in the ECM. The reading should be between 0.1-4.90 volts (1-425 psi), and change with pressure.

1. Ignition OFF, disconnect the harness connector at the A/C refrigerant pressure sensor.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 1 and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground. If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Verify the scan tool A/C High Side Pressure Sensor parameter is less than 0.1 volts (1 psi). If greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM.
5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference circuit terminal 2. Verify the scan tool A/C High Side Pressure Sensor parameter is greater than 4.90 volts (425 psi). If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the A/C refrigerant pressure sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
2. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

When the A/C switch is pressed, the HVAC control assembly sends a serial data message to the engine control module (ECM) for an A/C request. This input will request the ECM to ground the A/C compressor clutch relay control circuit, which will switch the A/C CLTCH relay. With the relay contacts closed, battery voltage is supplied to the A/C compressor clutch assembly.

1. The ignition voltage is between 9-18 volts.
2. The engine speed is more than 600 RPM.
3. An A/C request is made.

1. A short to ground on the A/C compressor clutch relay control circuit
2. A short to voltage on the A/C compressor clutch relay control circuit
3. An open circuit on the A/C compressor clutch relay control circuit or relay
4. An internally shorted or excessively low resistance A/C clutch relay coil

1. The A/C clutch relay is commanded OFF.
2. The conditions for which the DTC was set will be stored in the Failure Records data only. No information will be stored as Freeze Frame data.

The history DTC will clear after 40 fault-free ignition cycles.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Air Delivery Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)
2. «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, disconnect the A/C relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the ignition circuit terminal 85 and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or a open/high resistance. If the circuit tests normal and ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.
4. Verify that a test lamp illuminates between the relay B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or a open/high resistance. If the circuit tests normal and B+ circuit fuse is open, replace the A/C clutch relay.
5. Disconnect the harness connector at the A/C clutch coil.
6. Test for less than 1 ohm between the ground circuit terminal A and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the A/C clutch coil.
8. Connect a 10-amp fused jumper wire between the B+ circuit terminal 30 and control circuit terminal 87. Verify the A/C clutch is activated. If the A/C clutch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the A/C clutch.
9. Connect a test lamp between the ignition circuit terminal 85 and the control circuit terminal 86.
10. Command the A/C relay output function ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.
11. If all circuits test normal, test or replace the A/C clutch relay.

1. Ignition OFF, disconnect the A/C COMP relay.
2. Test for 60-180 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
4. Install a 30-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Air Conditioning Compressor Replacement (LZ4, LZE)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) or «Air Conditioning Compressor Replacement (LY7)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) or «Air Conditioning Compressor Replacement (LAT)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
2. «Relay Replacement (Attached to Wire Harness)»(/chevrolet/malibu/vii-2008-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/chevrolet/malibu/vii-2008-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
3. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module and ECM replacement, setup, and programming

Symptoms - HVAC Systems - Automatic

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to: «Air Delivery Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation) «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to «Checking Aftermarket Accessories»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Verify the A/C compressor clutch turns freely and is not seized.
4. Verify that the customer is using the correct key to enable personalization and is not inadvertently activating steering wheel or passenger HVAC controls.
5. The A/C compressor will not operate in cold outside air temperatures. Refer to «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation) .
6. The following conditions may cause window fogging: Wet carpet or mats High humidity Interior water leak Blocked A/C evaporator drain tube Maximum passenger capacity Blocked body pressure relief valves
7. Inspect the air distribution system for causes of reduced air flow: Obstructed or dirty passenger compartment air filter, if equipped Blocked or damaged air inlet or outlet vents

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Air Conditioning Compressor Malfunction»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
2. «Blower Motor Malfunction»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
3. «Leak Testing»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
4. «Defrosting Insufficient»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__defrosting-insufficient)
5. «Noise Diagnosis - Blower Motor»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-blower-motor)
6. «Noise Diagnosis - Air Conditioning (A/C) System»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-air-conditioning-ac)
7. «Odor Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__odor-diagnosis)
8. «Noise Diagnosis - HVAC Module»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__noise-diagnosis-hvac-module)

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

When the A/C switch is pressed, the HVAC control assembly sends a serial data message to the engine control module (ECM) for an A/C request. This input will request the ECM to ground the A/C compressor clutch relay control circuit, which will switch the A/C CLUTCH relay. With the relay contacts closed, battery voltage is supplied to the A/C compressor clutch assembly.

The following conditions must be met in order for the ECM to turn on the compressor clutch

1. The battery voltage is between 9-18 volts.
2. The engine coolant temperature (ECT) is less than 123°C (253°F).
3. The engine speed is less than 4,760 RPM.
4. The engine speed is more than 600 RPM.
5. The A/C high side pressure is between 2929-269 kPa (425-39 psi).
6. The throttle position is less than 100 percent.
7. The evaporator temperature is greater than 0°C (32°F).
8. The ECM does not detect excessive torque load.
9. The ECM does not detect insufficient idle quality.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Air Temperature Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, disconnect the A/C CLUTCH relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the ignition circuit terminal 85 and ground. If the test lamp does not illuminate, test the ignition circuit for a short to ground or a open/high resistance.
4. Verify that a test lamp illuminates between the relay B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or a open/high resistance.
5. Disconnect the harness connector at the A/C clutch coil.
6. Test for less than 1 ohm between the ground circuit terminal A and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the A/C clutch coil.
8. Connect a 10-amp fused jumper wire between the B+ circuit terminal 30 and control circuit terminal 87. Verify the A/C clutch is activated. If the A/C clutch does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the A/C clutch.
9. Connect a test lamp between the ignition circuit terminal 85 and the control circuit terminal 86.
10. Command the A/C relay output function ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.
11. If all circuits test normal, test or replace the A/C clutch relay.

1. Ignition OFF, disconnect the A/C COMP relay.
2. Test for 60-180 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
4. Install a 30-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Relay Replacement (Attached to Wire Harness)»(/chevrolet/malibu/vii-2008-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) or «Relay Replacement (Within an Electrical Center)»(/chevrolet/malibu/vii-2008-2012/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
2. «Air Conditioning Clutch Assembly Replacement»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
3. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The blower motor control module is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive and ground circuits enable the control module to operate. The HVAC control module provides a variable voltage to the blower motor control module to request the selected blower speed. The blower motor control module provides a pulse width modulation (PWM) signal to the blower motor in order to control the blower motor speed. The module supplies 12 volts to the blower motor through the blower motor voltage supply circuit.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Air Temperature Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the blower motor ON and OFF with a scan tool. Monitor/feel the operation of the blower motor.

1. Ignition OFF, disconnect the harness connector at the blower motor control module.
2. Test for less than 1.0 ohm between the ground circuit terminal A and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal C and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse (HVAC BLWR 40-amp) in the underhood fuse block is open, test all components connected to the B+ circuit and replace as necessary.
4. Connect a DMM between the control circuit terminal B and voltage.
5. Cycle the blower motor from OFF to HIGH. The voltage should increase while changing between the commanded states. If voltage remains greater than 11.5 volts while changing between the commanded states, test the control circuit for a short to ground. If the circuit test normal, replace the HVAC control module. If voltage remains less than 1.0 volts while changing between the commanded states, test the control circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module. If voltage is between 1.0-11.5 volts and does not increase when changing between the commanded states, replace the HVAC control module.
6. Ignition OFF, reconnect the harness connector at the blower motor control module. Disconnect the harness connector at the blower motor.
7. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the blower motor control module.
8. Connect a test lamp between the control circuit terminal B and the B+ circuit terminal A.
9. Turn the blower motor on high speed then to low speed. The test lamp intensity should be bright when in high speed and very dim or off when the blower is on low speed. If the test lamp intensity does not vary, test the control circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the blower motor control module.
10. If all circuits test normal, test or replace the blower motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Blower Motor Replacement»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning)
2. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/chevrolet/malibu/vii-2008-2012/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Air Temperature Sensors

The air temperature sensors are a 2-wire negative temperature co-efficient thermistor. The vehicle uses the following air temperature sensors

1. Ambient air temperature sensor
2. Upper air temperature sensor
3. Lower air temperature sensor

A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal voltage decreases as the resistance decreases. The sensor operates within a temperature range between -40 to +101°C (-40 to +215°F). The sensor signal varies between 0-5 volts. The input of the duct air temperature sensors are different from the ambient and inside air temperature sensors. The HVAC control module converts the signal to a range between 0-255 counts. As the air temperature increases the count value will decrease.

Sun Load Sensor Assembly

The sunload sensor is a 2-wire photo diode. The vehicle uses a single sunload sensor. The sensor is integrated into the sunload sensor assembly along with the ambient light sensor. Body ground and signal circuits enable the sensor to operate. As the sunload increases, the sensor signal decreases. The sensor operates within an intensity range between completely dark and very bright. The sensor signal varies between 0-5 volts. The body control module (BCM) converts the signal to a range between 0-255 counts. The sunload sensor provides the HVAC control module with a measurement of the amount of light shining on the vehicle. Bright or high intensity light causes the vehicles interior temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

1. «Air Delivery Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-delivery-description-and-operation)
2. «Air Temperature Description and Operation»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__air-temperature-description-and-operation)

Electrical Information Reference

1. «Circuit Testing»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures)
4. «Wiring Repairs»(/chevrolet/malibu/vii-2008-2012/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, cover the sunload sensor assembly with a shop towel or other suitable item. Verify the scan tool Right Sunload Sensor and Left Sunload Sensor parameters are within 3 counts of each other. If not within the specified range, refer to «Sun Load Sensor Circuit Malfunction»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sun-load-sensor-circuit-malfunction) .
2. Measure actual outside air temperature using a thermometer. Compare this value to the scan tool Ambient Air Temp Sensor parameter. The measured temperature should be within 5 degrees of parameter. If not within the specified range, refer to «Ambient Air Temperature Sensor Circuit Malfunction»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__ambient-air-temperature-sensor-circuit-malfunction) .
3. Measure actual temperature using a thermometer at each of the duct temperature sensors. Compare this value to the appropriate scan tool Duct Actual parameter. The measured temperature should be within 5 degrees of appropriate Duct Actual parameter. If not within the specified range, refer to «Duct Temperature Sensor Circuit Malfunction»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__duct-temperature-sensor-circuit-malfunction) .

Sun Load Sensor Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the sunload sensor.
2. Test for less than 10 ohms between the ground circuit terminal C and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, test for 4.8-5.2 volts between the ground circuit terminal C and the appropriate signal circuit terminal A. If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the HVAC control module. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.
4. If all circuits test normal, test or replace the sunload sensor.

Ambient Air Temperature Sensor Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the ambient temperature sensor.
2. Test for less than 1 ohm between the low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
3. Ignition ON, verify the appropriate scan tool Ambient Air Temp Sensor Voltage parameter is greater than 4.9 volts or 250 counts. If less than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Temp Sensor Voltage parameter is less than 0.1 volt or 5 counts. If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the appropriate temp sensor.

Duct Temperature Sensor Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate air duct temperature sensor.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal B and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
3. Ignition ON, verify that both the appropriate scan tool Duct Air Temp. Sensor parameter is less than 5 counts. If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the HVAC control module.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the appropriate scan tool Duct Air Temp. Sensor parameter is greater than 250 counts. If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
5. If all circuits test normal, test or replace the appropriate air temperature sensor.

1. A thermometer can be used to test the sensor off the vehicle in warm and or cold water. Refer to «Sensor Resistance Table (Inside Air Temperature Sensor)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table-inside-air-temperature) or «Sensor Resistance Table (Upper and Lower Duct Temp Sensors)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table-upper-and-lower) or «Sensor Resistance Table (Duct Temp conversion temp to counts)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table-duct-temp-conversion) or «Sensor Resistance Table (Ambient Air Temp Sensor)»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic__sensor-resistance-table-ambient-air-temp) for this test.
2. Test the appropriate temperature sensor by varying the sensor temperature in water while monitoring the sensor resistance.
3. Compare the readings with the Temperature VS Resistance table and verify that the resistance is within 5 percent of the specification. If not within the specified range, replace the sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Duct Air Temperature Sensor Replacement - Upper»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
2. «Duct Air Temperature Sensor Replacement - Lower»(/chevrolet/malibu/vii-2008-2012/remont/automatic-hvac-system/#hvac-system-automatic)
3. «Ambient Light Sensor Replacement»(/chevrolet/malibu/vii-2008-2012/remont/exterior-lights/#lighting-system)
4. «Control Module References»(/chevrolet/malibu/vii-2008-2012/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM and HVAC control module replacement, setup, and programming

Afterblow Enabling

The afterblow mode can be enabled using the scan tool. The afterblow mode allows the blower motor to operate after the engine has been turned off. This operation of the blower motor dries the evaporator core, which reduces the amount of microbial growth which can create undesirable odors.

Use the following procedure in order to enable the afterblow mode

1. Connect the Scan Tool.
2. Turn ON the ignition, with the engine OFF.
3. Select HVAC Module.
4. Select HVAC Systems Automatic.
5. Select BCM.
6. Select Module Setup.
7. Select Afterblow Option.
8. Upon selecting the afterblow option a asterix will appear next to the word afterblow meaning the function is enabled.
9. Select the save option in the lower left of the screen.

When afterblow has been enabled by the scan tool the blower motor will operate at 68 percent blower speed for 2 minutes 30 seconds to 4 minutes after the engine has been in Key OFF for 30 minutes.

The following conditions must be met for the HVAC module to operate the afterblow

1. The outside air temperature must be at least 21°C (70°F).
2. The A/C compressor must have operated during the latest key cycle.
3. The engine must be turned off for at least 30 minutes.
4. The system voltage must be at least 12 volts.

Actuator Recalibration

When replacing an air temperature, mode, recirculation actuator or HVAC control module the following calibration process needs to be performed

1. Place the ignition switch to the OFF position.
2. Disconnect the battery.
3. Disconnect the scan tool.
4. Install the HVAC control module or appropriate actuator.
5. Connect all previously disconnected components.
6. Connect the battery.
7. Place the ignition switch to the ON position.
8. Calibration of the air temperature, recirculation and mode doors happens taking roughly 13 seconds.
9. Verify that no DTCs have set as current DTCs.

Scheme 46

Scheme 47

Scheme 48

Scheme 49

Scheme 50

Scheme 51

Removal Procedure

1. Remove the right front floor console extension panel. Refer to «Front Floor Console Extension Panel Replacement - Right Side»(/chevrolet/malibu/vii-2008-2012/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .
2. Twist and pull the lower air temperature sensor from the center floor air outlet duct.
3. Remove the lower air temperature sensor wire harness.

Installation Procedure

1. Install the lower air temperature sensor wire harness.
2. Install the lower air temperature sensor.
3. Install the right front floor console extension panel. Refer to «Front Floor Console Extension Panel Replacement - Right Side»(/chevrolet/malibu/vii-2008-2012/remont/exteriorinterior-trim/#instrument-panel-trim-and-console-trim) .

Scheme 52

Air Delivery Description and Operation

The air delivery controls are divided into 4 areas

1. HVAC control components
2. Air speed
3. Air distribution
4. Recirculation operation
5. Automatic operation

HVAC Control Module

The HVAC control module is a GMLAN device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The control module communicates on the low-speed data bus. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, then all HVAC DTCs and settings will be erased from KAM. The temperature display reading at the control head can be converted from °C to °F by pressing the Auto button for a minimum of 3 seconds. The ignition 3 voltage circuit provides a device on signal. The control module supports the following features

Mode/Recirculation Actuator

The mode and recirculation actuators are 5-wire bi-directional electric motors that incorporate a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuators to operate. The control circuits use either a 0 or 12-volt value to coordinate the actuators movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts.

Blower Motor Control Processor

The blower motor control processor is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive voltage and ground circuits enable the control processor to operate. The HVAC control module provides a pulse width modulation (PWM) signal to the control processor in order to command the blower motor speed. The processor supplies 12 volts to the blower motor through the blower motor voltage supply circuit. The control processor uses the blower motor ground as a low side control to adjust the blower motor speed.

Air Speed

The blower motor forces air to circulate within the vehicles interior. The vehicle operator determines the blower motors speed by placing the blower motor switch in a desired speed position. The blower motor will only operate if the blower motor switch is in any position other than OFF, and the ignition switch is in the RUN position.

Once a blower speed is selected, the blower speed remains constant until a new speed is selected.

As the requested blower speed increases, the following conditions occur

1. The HVAC control module increases the amount of time that the blower motor speed control circuit is modulated to ground.
2. The voltage and duty cycle, measured between the blower motor speed control circuit and ground, decrease.

As the requested blower speed decreases, the following conditions occur

1. The HVAC control module decreases the amount of time that the blower motor speed control circuit is modulated to ground.
2. The voltage and duty cycle, measured between the blower motor speed control circuit and ground, increase.

Afterblow

Afterblow is a feature that dries the evaporator core by operating the blower motor after the engine is turned off. This reduces the amount of microbial growth that can create undesirable odors. The vehicle does not come equipped with the afterblow feature turned on. If the afterblow feature is required due to an odor concern, it must be turned on by the scan tool. Any C68 HVAC control head built before part number 25782408 will not support the afterblow enabling process. These control heads will need a reflash of the HVAC control head to update older software, then enabling of the afterblow process through the scan tool can be enabled.

The following conditions must be met for afterblow to operate

1. The A/C compressor operated during the latest key cycle.
2. The system voltage is at least 11 volts to start and 10 volts to continue to run.
3. The ignition has been in the OFF position for at least 30 minutes.

Once the above conditions have been met the following sequence of events will occur

1. The blower will run for 150 seconds (2 minutes 30 seconds) at 68 percent blower speed.
2. The recirculation door moves to outside air position.
3. The mode valve moves to the floor position.

Air Distribution

The HVAC control module controls the mode actuator in order to distribute airflow to a desired outlet. The mode switch provides the vehicle operator with the ability to override the automatic setting. When the mode switch is moved to the bi-level through defrost positions, the A/C compressor clutch engages and the recirculation actuator will be moved to the outside air position. When VENT is pressed, the following will occur

1. The mode valve will be moved to the panel position.
2. The recirculation actuator will follow user request if blower is on and power mode is in run.
3. The A/C compressor will follow user request if blower is on and power mode is in run.

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

1. The blower motor switch must be in the AUTO position.
2. The air temperature switch must be in any other position other than 60 or 90 degrees.
3. 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

1. Regulate blower motor speed
2. Position the air temperature actuator
3. Position the mode actuator
4. Position the recirculation actuator
5. 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

1. 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.
2. 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.
3. 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

1. Radio - Driver Information Center (DIC)
2. Automatic operation
3. The Heating and Air Conditioning System
4. The A/C cycle

Radio Display

This vehicle is equipped with a driver information center (DIC) and it displays outside temperature through the radio display. If an outside temperature display concern occurs please refer to Outside Air Temperature Display Inaccurate or Inoperative .

The Radio/IPC displays the outside air temperature value that it receives through a Low Speed GMLAN message. The scan tool has the ability to update the displayed ambient air temperature. The HVAC Manual Tech 2 shows the ambient air temperature sensor feedback voltage under Body and Accessories / Data Display / BCM. The HVAC Auto System there is a temperature reading under HVAC / Data Display / HVAC / Sensor Data. Both readings are unfiltered so it is possible that the temperature read on the tech 2 will differ from the temperature displayed on the DIC/Radio without there being a problem with the vehicle. The DIC/Radio only displays the reading being sent from the BCM. The outside air temperature value is displayed or updated under the following conditions

The HVAC control module is a GMLAN device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The control module communicates on the low-speed data bus. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, then all HVAC DTCs and settings will be erased from KAM. The temperature display reading at the control head can be converted from °C to °F by pressing the Auto button for a minimum of 3 seconds. The HVAC control module during defrost modes will change the A/C compressor LED status from on to off. The ignition 3 voltage circuit provides a device on signal or backup indication as to the vehicles wake up power mode. The control module supports the following features

Air Temperature Actuator

The air temperature actuator is a 5-wire bi-directional electric motor that incorporate a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuator to operate. The control circuits use either a 0 or 12-volt value to coordinate the actuators movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts.

The air temperature sensors are 2-wire negative temperature co-efficient thermistors. The vehicle uses the following air temperature sensors

1. Ambient
2. Inside
3. Upper duct air temperature sensor
4. Lower duct air temperature sensor

A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor signal decreases as the resistance decreases. The sensor signal varies between 0-5 volts. The HVAC control module converts the signal to a range between 0-255 counts.

The inside air temperature sensor is located within the HVAC control module. Replacement of this sensor involves the replacement of the HVAC control module. The inside air temperature sensor operates within a temperature range between -40 to +185°C (-40 to +365°F). If the sensor is shorted to ground, voltage, or an open, the system will operate using an estimated default value to allow the system to operate. The ambient temperature sensor operates within a temperature range between -40 to +87.5°C (-40 to +189.5°F). The sensor signal is read by the body control module (BCM), scaled appropriately and transmitted to the HVAC control module through the Low Speed bus. If the sensor is shorted to ground, voltage, or an open, the system will operate using a signal scaled appropriately to allow the system to operate.

The duct temperature sensor temperature response is different from the ambient and inside sensors. A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases the sensor resistance decreases. The sensor operates within a temperature range between -40 to +80°C (-40 to +176°F).

Sunload Sensor

The sunload sensor is a 2-wire photo diode. The vehicle uses a single sunload sensor. The sensor is integrated into the ambient light sensor assembly along with the ambient light sensor. Low reference and signal circuits enable the sensor to operate. As the sunload increases, the sensor signal decreases. The sensor operates within an intensity range between completely dark and bright. The sensor signal varies between 0-5 volts. The sensor signal is read by the BCM, scaled appropriately and transmitted to the HVAC control module through the GM LAN Low Speed bus. Bright, or high intensity, light causes the vehicles inside temperature to increase. The HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle.

A/C Refrigerant Pressure Sensor

The A/C refrigerant pressure sensor is a 3-wire piezoelectric pressure transducer. A 5-volt reference, low reference, and signal circuits enable the sensor to operate. The A/C pressure signal can be between 0-5 volts. When the A/C refrigerant pressure is low, the signal value is near 0 volts. When the A/C refrigerant pressure is high, the signal value is near 5 volts.

The A/C refrigerant pressure sensor prevents the A/C system from operating when an excessively high or low pressure condition exists.

If the powertrain control module (PCM) or engine control module (ECM) detects a failure in the A/C refrigerant pressure sensor or A/C High Side Pressure sensor circuit, the GM LAN Low Speed bus message sent to the HVAC control module will be invalid.

The afterblow function is not enabled from the factory. To enable function the following must occur. As soon as ignition is turned OFF, and all active processes are complete, the controller is put into sleep or low power mode. A high voltage wakeup is generated on the low speed GMLAN by the BCM and the HVAC virtual network is activated. Embedded in GMLAN message is Afterblow control logic bit (Aftrblw_Active). The afterblow resides in the BCM. The BCM has a timer that tells the HVAC Control module to go to Hi blower. The HVAC afterblow function is used to eliminate the odor associated with A/C usage. The "After Blow" is a method where by the HVAC blower is run for a few minutes after the vehicle is turned OFF in order to physically blow off excess condensation and eliminate odors.

Replacement of the inside air temperature sensor means replacing the HVAC control module. The inside air temperature sensor is an integral part of the HVAC control module. The HVAC control module monitors the passenger compartment inside air temperature through an inside air temperature sensor. When the air is cold, the sensor resistance and the signal voltage are high. When the air is warm, the sensor resistance and the signal voltage are low. The HVAC control module requests A/C compressor clutch engagement and controls the air temperature actuator door positions in order to maintain the selected air temperature. The HVAC control module sends out a 5-volt reference signal to the inside air temperature sensor over the 5-volt reference circuit. A thermistor varies the reference voltage back to the HVAC control module through the low reference circuit. The sensor is capable of sensing a temperature range of -40 to +85°C (-40 to +185°F).

Heating and A/C Operation

The purpose of the heating and A/C system is to provide the following

1. Heated air
2. Cooled air
3. Remove humidity from the interior of the vehicle
4. Reduce windshield fogging

Regardless of the temperature setting, the following can effect the rate that the HVAC system can achieve a desired temperature

1. Recirculation actuator setting
2. Difference between inside and desired temperature
3. Difference between ambient and desired temperature
4. Blower motor speed setting
5. Mode setting

The HVAC control module commands or monitors the following actions when an air temperature setting is selected

1. Warmest position-The air temperature actuator door position directs maximum air flow through the heater core.
2. Coldest position-The air temperature actuator door position directs maximum air flow around the heater core.
3. 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 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

1. HVAC control module-The control module operating range is 9-16 volts.
2. 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).
3. BCM-Battery voltage between 9-16 volts.

Once engaged, the compressor clutch will be disengaged for the following conditions

1. Throttle position is 100 percent.
2. A/C pressure is more than 2997 kPa (435 psi).
3. A/C pressure is less than 248 kPa (36 psi).
4. ECT is more than 120°C (248°F).
5. Engine speed is more than 5,000 RPM.
6. Transmission shift
7. The PCM or ECM detects excessive torque load.
8. The PCM or ECM detects insufficient idle quality.
9. 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

1. The blower motor switch must be in the AUTO position.
2. The air temperature switch must be in any other position other than 60 or 90 degrees.
3. 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

1. Regulate blower motor speed
2. Position the air temperature actuator
3. Position the mode actuator
4. Position the recirculation actuator
5. 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

1. 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.
2. 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.
3. 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.

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Component Connector End Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Ambient Light Sensor Replacement
• Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement
• Relay Replacement (Attached to Wire Harness)
• Checking Aftermarket Accessories
• Defrosting Insufficient
• Noise Diagnosis - Blower Motor
• Noise Diagnosis - Air Conditioning (A/C) System
• Odor Diagnosis
• Noise Diagnosis - HVAC Module
• Instrument Panel Accessory Trim Plate Replacement
• Fastener Caution
• Communication Interface Module Replacement
• Radiator Center Grille Replacement (Lower)
• Outside Air Temperature Display Inaccurate or Inoperative
• DTC B0158
• Air Temperature Description and Operation
• Air Delivery Description and Operation
• Sensor Resistance Table (Inside Air Temperature Sensor)
• Sensor Resistance Table (Upper and Lower Duct Temp Sensors)
• Sensor Resistance Table (Duct Temp conversion temp to counts)
• Sensor Resistance Table (Ambient Air Temp Sensor)
• Sun Load Sensor Circuit Malfunction
• Ambient Air Temperature Sensor Circuit Malfunction
• Duct Temperature Sensor Circuit Malfunction