HVAC System - Automatic Buick Encore I

Scheme 66

Scheme 67

Scheme 68

Scheme 69

Scheme 70

HVAC Component Replacement Reference

HVAC Component Replacement Reference

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

DTC Descriptors

For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The ambient light/sunload sensor integrates the sunload and passenger compartment temperature functions within a single assembly.

The solar sensor uses 4 unique circuits as detailed below

1. Low reference circuit - This is a common ground for the ambient light/sunload sensor assembly.
2. Temperature signal circuit - This is the signal circuit for the temperature sensor.
3. Clock signal circuit - This has 2 functions, via a high side PWM signal, the HVAC control module supplies power to the sensor as well as a clock input for the sensor microprocessor.
4. Sunload signal circuit - This is used as an output from the solar sensor to the HVAC control module to transmit sun heat (IR) intensity, elevation, and azimuth data.

The passenger compartment temperature sensor is a negative temperature coefficient thermistor. As the air temperature increases, the sensor resistance decreases. The sensor signal varies between 0-5 V.

Bright or high intensity light causes the vehicles interior temperature to increase. The automatic HVAC system compensates for the increased temperature by diverting additional cool air into the vehicle.

Conditions for Running the DTC

1. Ignition ON
2. The HVAC control module is ON.

Conditions for Setting the DTC

B0163 02

The input signal is out of range. The HVAC control module detects voltage less than 0.1 V on the temperature signal circuit.

B0163 05

The input signal is out of range. The HVAC control module detects voltage greater than 4.9 V on the temperature signal circuit.

B0183 02

The input signal is out of range. The HVAC control module detects voltage less than 0.1 V on the solar sensor signal circuit.

B0183 05

The input signal is out of range. The HVAC control module detects voltage greater than 4.9 V on the solar sensor signal circuit.

B1405 02

The input signal is out of range. The HVAC control module detects voltage less than 10 V on the clock/power supply circuit.

B1405 05

The input signal is out of range. The HVAC control module detects a short to voltage or an open the clock/power supply circuit.

Action Taken When the DTC Sets

B0163 02, B0163 05, B0183 02, B0183 05

The system will use the last valid values as a default.

B1405 02, B1405 05

If no value is read at the time of fault, the HVAC control module uses 0 W/m 2 as intensity.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify DTCs B0163 and B0183 are not both set concurrently. If both DTCs are set Refer to Low Reference Test. If both DTCs are not set
2. Verify DTC B0163, B0183, or B1405 is not set. If one of the DTCs is set Refer to the appropriate diagnostic in Circuit/System Testing. If none of the DTCs are set
3. Verify the B10B Ambient Light/Sunload Sensor is accurate. If the sensor is not accurate Perform the following Circuit/System Testing in the order listed below: Circuit/System Testing - Low Reference Test Circuit/System Testing - DTC B0163 Circuit/System Testing - DTC B1405 Circuit/System Testing - DTC B0183 If the sensor is accurate
4. All OK.

Circuit/System Testing

Low Reference Test

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B10B Ambient Light/Sunload Sensor. It may take up to 10 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal 6 and ground. If 10 ohms or greater Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If less than 10 ohms
3. Test or replace the B10B Ambient Light/Sunload Sensor.

DTC B0163

1. Ignition OFF, disconnect the harness connector at the B10B Ambient Light/Sunload Sensor, ignition ON.
2. Verify the scan tool Passenger Compartment Air Temperature (Unfiltered) parameter is less than -37°C (-35°F). If -37°C (-35°F) or greater Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module. Test for infinite resistance between the signal circuit terminal 3 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K33 HVAC Control Module. If less than -37°C (-35°F)
3. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 6.
4. Verify the scan tool parameter Passenger Compartment Air Temperature (Unfiltered) parameter is greater than 78°C (172°F). If 78°C (172°F) or less Ignition OFF, remove the jumper wire and disconnect the harness connector at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Ignition OFF. Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If greater than 78°C (172°F)
5. Test or replace the B10B Ambient Light/Sunload Sensor.

DTC B0183

1. Ignition OFF, disconnect the harness connector at the B10B Ambient Light/Sunload Sensor, ignition ON.
2. Test for 4.8-5.2 V between the signal circuit terminal 4 and ground. If less than 4.8 V Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module. Test for infinite resistance between the signal circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If greater than for 5.2 V Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K33 HVAC Control Module. If between 4.8-5.2 V
3. Test or replace the B10B Ambient Light/Sunload Sensor.
4. Verify DTC B0183 did not reset. If DTC B0183 reset Replace the K33 HVAC Control Module. If DTC B0183 did not reset
5. All OK.

DTC B1405

1. Ignition OFF, disconnect the harness connector at the B10B Ambient Light/Sunload Sensor, ignition ON.
2. Test for greater than 10 V between signal circuit terminal 2 and ground. If less than 10 V Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module. Test for infinite resistance between signal circuit terminal 2 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If 10 V or greater
3. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module, ignition ON.
4. Test for less than 1 V between the signal circuit terminal 2 and ground. If 1 V or greater Repair the short to voltage on the circuit. If less than 1 V
5. Test or replace the B10B Ambient Light/Sunload Sensor.
6. Verify DTC B1405 did not reset. If DTC B1405 reset Replace the K33 HVAC Control Module. If DTC B1405 did not reset
7. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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

1. Air temperature sensor - left upper
2. Air temperature sensor - left lower
3. Air temperature sensor - right upper
4. Air temperature sensor - right lower
5. A/C evaporator temperature sensor

This sensor operates using signal and low reference circuits. As the air temperature surrounding the sensor increases, the sensor resistance decreases. The sensor sends a signal voltage between 0-5 V. If the HVAC control module detects a malfunctioning sensor the software uses a default air temperature value. The default action ensures that the HVAC system can adjust the inside air temperature near the desired temperature until the condition is corrected.

1. Ignition ON.
2. The HVAC control module is ON.

The HVAC control module detects the sensor signal out of range. The signal voltage is less than 0.1 V or greater than 4.9 V for more than 50 ms.

The system operates using a default value.

The sensor signal is within specified range between 0.1-4.9 V.

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON.
2. Verify DTC B3933 is not set. If DTC B3933 is set Refer to Circuit/System Testing - Without Scan Tool Support. If DTC B3933 is not set
3. Verify the appropriate temperature sensor has a parameter displayed in HVAC scan tool information. If there is no scan tool parameter Refer to Circuit/System Testing - Without Scan Tool Support. If there is a scan tool parameter
4. Refer to Circuit/System Testing - With Scan Tool Support

With Scan Tool Support

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate temperature sensor. It may take up to 10 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal B and ground. If 10 ohms or greater Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If less than 10 ohms
3. Ignition ON.
4. Verify the appropriate scan tool temperature sensor parameter is less than -37°C (-35°F) If greater than -37°C (-35°F) Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module. Test for infinite resistance between the signal circuit terminal A and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K33 HVAC Control Module. If -37°C (-35°F) or less
5. Install a 3 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B.
6. Verify the scan tool temperature sensor parameter is greater than 77°C (170°F). If less than 77°C (170°F) Ignition OFF, remove the jumper wire and disconnect the harness connectors at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Ignition OFF Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If 77°C (170°F) or greater
7. Test or replace the temperature sensor.

Without Scan Tool Support

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate temperature sensor. It may take up to 10 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal B and ground. If 10 ohms or greater Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If less than 10 ohms
3. Test for 4.8-5.2 V between the signal circuit terminal A and ground. If less than 4.8 V Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module. Test for infinite resistance between the signal circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If greater than 5.2 V Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the signal circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K33 HVAC Control Module. If between 4.8-5.2 V
4. Test or replace the temperature sensor.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
6. Verify the DTC does not set. If the DTC sets Replace the K33 HVAC Control Module. If the DTC does not set
7. All OK

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

For symptom byte information, refer to Symptom Byte List .

The windshield temperature and inside moisture sensor includes the relative humidity sensor, windshield temperature sensor and humidity sensing element temperature sensor all in one assembly.

This sensor assembly provides information about

1. Relative humidity level at the windshield inside the vehicle
2. Temperature of the windshield inside the vehicle
3. Temperature of the humidity sensor element

The relative humidity sensor measures the relative humidity of the compartment side of the windshield. It also detects the temperature of the windshield surface on the compartment side. Both values are used as control inputs for the HVAC control module application to calculate the fog risk on windshield compartment side and ability to reduce fuel consumption by decreasing A/C compressor usage to a minimum without causing any fog. The sensor will also enable partial recirculation mode in order to improve heat-up performance of the passenger compartment under cold ambient temperature conditions without the risk of mist build-up on the windshield. The humidity sensor element temperature sensor supplies the temperature of the humidity sensor element. It is only needed if the thermal contact between the humidity sensing element and the inside windshield surface is not sufficient.

1. Ignition ON.
2. The HVAC control module is ON.

B018A 02, B048C 02, or B048F 02

The HVAC control module detects the sensor signal out of range. The signal voltage is less than 0.1 V for more than 50 ms.

B018A 05, B048C 05, B048F 05 or B1395 07

The HVAC control module detects the sensor signal out of range. The signal voltage is greater than 4.9 V for more than 50 ms.

B1395 03

The HVAC control module detects the 5 V reference voltage out of range. The 5 V reference voltage is less than 4.5 V for more than 50 ms.

B1395 07

The HVAC control module detects the 5 V reference voltage out of range. The 5 V reference voltage is greater than 5.5 V for more than 50 ms.

1. The system will use the last valid values as default.
2. If no value is read at the time of fault, the HVAC control module uses 60% for humidity.

The condition for setting the DTC is no longer present.

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B160 Windshield Temperature and Inside Moisture Sensor. It may take up to 10 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal 3 and ground. If 10 ohms or greater Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If less than 10 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground. If less than 4.8 V Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module. Test for infinite resistance between the 5 V reference circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the 5 V reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If greater than 5.2 V Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the 5 V reference circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K33 HVAC Control Module. If between 4.8-5.2 V
5. Verify the scan tool parameters listed below are less than -37°C (-35°F). Windshield Temperature Passenger Compartment Humidity Sensor Temperature If -37°C (-35°F) or greater Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module. Test for infinite resistance between the signal circuit terminals listed below and ground: Windshield temperature sensor signal terminal 4 Passenger compartment humidity sensor temperature signal terminal 5 If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K33 HVAC Control Module. If less than -37°C (-35°F)
6. Install a 3 A fused jumper wire between the low reference circuit terminal 3 and each signal circuit terminal listed below: Windshield temperature sensor signal terminal 4 Passenger compartment humidity sensor temperature signal terminal 5
7. Verify the appropriate scan tool parameter listed below is greater than 114°C (238°F). Windshield Temperature Passenger Compartment Humidity Sensor Temperature If 114°C (238°F) or less Ignition OFF, remove the jumper wire and disconnect the harness connectors at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the signal circuit terminals listed below and ground: Windshield temperature sensor signal terminal 4 Passenger compartment humidity sensor temperature signal terminal 5 If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If greater than 114°C (238°F)
8. Remove the jumper wire.
9. Verify the scan tool Passenger Compartment Humidity parameter is greater than 95%. If 95% or less Ignition OFF, disconnect the harness connectors at the K33 HVAC Control Module, ignition ON. Test for infinite resistance between the signal circuit terminal 2 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K33 HVAC Control Module. If greater than 95%
10. Install a 3 A fused jumper wire between the passenger compartment humidity signal circuit terminal 2 and the low reference circuit terminal 3.
11. Verify the scan tool Passenger Compartment Humidity Sensor parameter is less than 5%. If 5% or greater Ignition OFF, remove the jumper wire and disconnect the harness connectors at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the signal circuit terminal 2 and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If less than 5%
12. Test or replace the B160 Windshield Temperature and Inside Moisture Sensor.

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/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 control module has 4 circuits: a B+ input, a signal input from the HVAC control module, a B+ output to the blower motor, and a low side pulse width modulation (PWM) output. The HVAC control module provides a low side (PWM) signal to the blower motor control module in order to request the blower motor speed. The blower motor control module grounds the blower motor using a low side PWM signal in order to vary the blower motor speed.

1. Ignition ON.
2. The HVAC control module is ON.

B0193 01

The voltage at the HVAC control module output to the blower motor control module is always high.

B0193 06

The voltage at the HVAC control module output to the blower motor control module is always low or fluctuating.

The blower motor is inoperative.

The condition for setting the DTC is no longer present.

Diagnostic Aids

Inspect the motor shaft for rust or other foreign material which may prohibit proper motor operation.

If the motor operates properly please reinstall it and check for Preliminary Information or Technical Service Bulletins.

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the K8 Blower Motor Control Module. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 5 and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 6 and ground. If the test lamp does not illuminate and the circuit fuse is good Ignition OFF, remove the test lamp. Test for less than 2 ohms in the B+ circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse. If the test lamp does not illuminate and the circuit fuse is open Ignition OFF, remove the test lamp. Test for infinite resistance between the B+ circuit terminal 6 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Disconnect the X2 harness connector at the K8 Blower Motor Control Module and disconnect the harness connector at the M8 Blower Motor. Test for infinite resistance between the M8 Blower Motor control circuit terminal B and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, test or replace the M8 Blower Motor. If the test lamp illuminates
5. Remove the test lamp.
6. Test for 2.6-3.2 V between the control circuit terminal 3 and ground. If less than 2.6 V Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance. Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms replace the K33 HVAC Control Module. If greater than 3.2 V Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K33 HVAC Control Module. If between 2.6-3.2 V
7. Ignition OFF, connect the X1 harness connector at the K8 Blower Motor Control Module and disconnect the harness connector at the M8 Blower Motor, ignition ON and blower ON.
8. Verify a test lamp illuminates between the control circuit terminal 1 and ground. If the test lamp does not illuminate Ignition OFF, disconnect the X2 harness connector at the K8 Blower Motor Control Module. Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms replace the K8 Blower Motor Control Module. If the test lamp illuminates
9. Connect a test lamp between control circuit terminal 1 and control circuit terminal 2.
10. Verify the test lamp becomes progressively brighter as the blower speed is increased and progressively dimmer as the blower speed is decreased. If the test lamp does not illuminate Ignition OFF, disconnect the X2 harness connector at the K8 Blower Motor Control Module, ignition ON. Test for less than 1 V between the control circuit terminal 1 and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms replace the K8 Blower Motor Control Module. If the test lamp illuminates, but does not change in brightness Ignition OFF, disconnect the X2 harness connector at the K8 Blower Motor Control Module. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K8 Blower Motor Control Module. If the test lamp changes in brightness as the blower speed is changed
11. Test or replace the M8 Blower Motor.

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Stepper motors are used for temperature regulation, air distribution control and recirculation door control.

With the switches and dials on the HVAC controls, air temperature door position, mode door position and recirculation door position can be selected. The selected values are passed to the HVAC control module via serial data. The HVAC control module supplies a 12 V control voltage to the stepper motors and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motors move the appropriate doors into the calculated positions, in order to reach the desired positions.

1. Ignition ON.
2. The HVAC control module is ON.

B023A 02

The stepper motors supply output is shorted to ground.

B0223 01, B022A 01, B0233 01, B023A 01, B0408 01 or B0418 01

At least one control circuits of the appropriate stepper motor is shorted to voltage when motor starts moving. Faults are not detected when motor is already running or target position is already reached.

B0223 06, B022A 06, B0233 06, B0233 06, B0408 06 or B0418 06

At least one control circuits of the appropriate stepper motor is shorted to ground or open when motor starts moving. Faults are not detected when motor is already running or target position is already reached.

B023A

1. The affected output will be switched off for hardware protection.
2. All stepper motors are deactivated.

B0223, B022A, B0233, B0408 or B0418

1. The affected output will be switched off for hardware protection.
2. The affected stepper motor is deactivated.

The condition for setting the DTC is no longer present.

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

1. Perform the «Actuator Recalibration»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) procedure.
2. Verify the concern or DTC has been corrected. If the concern or DTC has not been corrected Verify DTC B023A is not set. If DTC B023A is set Refer to Circuit/System Testing - DTC B023A. If DTC B023A is not set Refer to Circuit/System Testing - DTC B0223, B022A, B0233, B0408 or B0418. If the concern or DTC has been corrected
3. All OK.

DTC B023A

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the components listed below. It may take up to 2 min for all vehicle systems to power down. M37 Mode Door Actuator M46 Air Recirculation Door Actuator M6L Air Temperature Door Actuator - Left M6R Air Temperature Door Actuator - Right
2. Disconnect the X3 and X4 harness connectors at the K33 HVAC Control Module.
3. Test for infinite resistance between the K33 HVAC Control Module 12 V reference circuit terminal 15 X3 and ground. If less than infinite resistance Repair the short to ground on the circuit. If infinite resistance
4. Ignition ON.
5. Test for less than 1 V between the K33 HVAC Control Module 12 V reference circuit terminal 15 X3 and ground. If 1 V or greater Repair the short to voltage on the circuit. If less than 1 V
6. Connect the X3 and X4 harness connectors at the K33 HVAC Control Module, ignition ON.
7. Clear all DTCs.
8. Verify DTC B023A is not set. If the DTC is set. Replace the K33 HVAC Control Module. If the DTC is not set.
9. Verify DTC B023A does not set after connecting each of the components listed below one at a time and operating them through their full range. M37 Mode Door Actuator M46 Air Recirculation Door Actuator M6L Air Temperature Door Actuator - Left M6R Air Temperature Door Actuator - Right If the DTC sets Replace the component that was connected immediately before the DTC set. If the DTC does not set
10. All OK.

DTC B0223, B022A, B0233, B0408 or B0418

1. Ignition OFF, disconnect the harness connector at the appropriate door actuator, ignition ON.
2. Verify a test lamp flashes when connected between the 12 V reference circuit terminal 2 and ground. If the test lamp does not flash Ignition OFF, remove the test lamp and disconnect the harness connector at the K33 HVAC Control Module. Test for less than 2 ohms in the 12 V control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If the test lamp flashes
3. Connect a test lamp between each control circuit listed below and B+. Control Circuit - terminal 1 Control Circuit - terminal 3 Control Circuit - terminal 4 Control Circuit - terminal 6
4. Command the appropriate door actuator in both directions.
5. Verify the test lamp turns ON and then OFF during at least one of the directional commands. If the test lamp is always ON Ignition OFF, remove the test lamp and disconnect the harness connector at the K33 HVAC Control Module. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K33 HVAC Control Module. If the test lamp is always OFF Ignition OFF, remove the test lamp and disconnect the harness connector at the K33 HVAC Control Module, ignition ON. Test for less than 1 V between the control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Ignition OFF Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance is the circuit. If less than 2 ohms, replace the K33 HVAC Control Module. If the test lamp turns ON and then OFF
6. Replace the door actuator.

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of the 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 V reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the sensor signal to the ECM to vary. When the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low. The ECM may use this information to turn the cooling fans on as well as to monitor clutch engagement. The HVAC module will receive the A/C refrigerant pressure information from the ECM via serial data.

1. Engine is running.
2. Any of the conditions for setting the DTC are met for 15 s.
3. Battery voltage is between 11-18 V.

P0532

The ECM detects that the A/C pressure is less than 1 psi (0.25 V).

P0533

The ECM detects that the A/C pressure is more than 428 psi (4.92 V).

1. The A/C compressor is disabled.
2. The ECM will illuminate the malfunction indicator lamp (MIL).

The condition for setting the DTC is no longer present.

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

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (LUV) , Powertrain Diagnostic Trouble Code (DTC) Type Definitions (2H0)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON
2. Verify the scan tool engine control module A/C High Side Pressure Sensor parameter is between 6.8 kPa (1 psi) and 2950 kPa (428 psi). If not between 6.8 kPa (1 psi) and 2950 kPa (428 psi) Refer to Circuit/System Testing If between 6.8 kPa (1 psi) and 2950 kPa (428 psi)
3. All OK

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B1 A/C Refrigerant Pressure Sensor. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal 1 and ground. If 10 ohms or greater Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for less than 2 ohms in the low reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If less than 10 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 2 and ground. If less than 4.8 V Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. Test for infinite resistance between the 5 V reference circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the 5 V reference circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If greater than 5.2 V Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the 5 V reference circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K20 Engine Control Module. If between 4.8-5.2 V
5. Verify the scan tool A/C High Side Pressure Sensor parameter is less than .25 V. If .25 V or greater Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON. Test for less than 1 V between the signal circuit terminal 3 and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K20 Engine Control Module. If less than .25 V
6. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the 5 V reference circuit terminal 2.
7. Verify the scan tool A/C High Side Pressure Sensor parameter is greater than 4.8 V. If 4.8 V or less Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20 Engine Control Module. Test for infinite resistance between the signal circuit terminal 3 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the signal circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If greater than 4.8 V
8. Test or replace the B1 A/C Refrigerant Pressure Sensor.

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/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 module sends a serial data message to the engine control module (ECM) indicating the A/C request. In response to this message, the ECM grounds the A/C compressor clutch relay control circuit energizing the A/C compressor clutch relay. With the relay contacts closed, battery voltage is applied through the A/C compressor clutch control circuit activating the A/C compressor clutch.

1. The ignition voltage is between 11-18 volts.
2. The engine speed is greater than 600 RPM.
3. An A/C request is made.

P0645 or P0646

The ECM detects a short to ground or an open at the A/C compressor clutch relay control circuit.

P0647

The ECM detects a short to voltage at the A/C compressor clutch relay control circuit.

P0645 or P0646

The A/C compressor is inoperative or always active.

P0647

The A/C compressor is inoperative.

A history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction.

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (LUV) , Powertrain Diagnostic Trouble Code (DTC) Type Definitions (2H0)

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, and all vehicle systems OFF. Disconnect the harness connector at the Q2 A/C Compressor Clutch. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 10 ohms between the Q2 A/C Compressor Clutch ground circuit terminal A and ground. If 10 ohms or greater Ignition OFF. Test for less than 2 ohms in the ground circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, repair the open/high resistance in the ground connection. If less than 10 ohms
3. Connect a test lamp between the control circuit terminal B and ground, ignition ON.
4. Verify the test lamp does not turn ON and OFF when commanding the Q2 A/C Compressor Clutch On and Off with a scan tool. If the test lamp turns ON and OFF Test or replace the Q2 A/C Compressor Clutch. If the test lamp does not turn ON and OFF
5. Ignition OFF, connect the harness connector at the Q2 A/C Compressor Clutch. Disconnect the X3 harness connector at the X50A Fuse Block - Underhood, ignition ON.
6. Verify the Q2 A/C Compressor Clutch is not activated. If the Q2 A/C Compressor Clutch is activated Ignition OFF, disconnect the harness connector at the Q2 A/C Compressor Clutch, ignition ON. Test for less than 1 V between the control circuit terminal B and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, test or replace the Q2 A/C Compressor Clutch. If the Q2 A/C Compressor Clutch is not activated
7. Connect a 10 A fused jumper wire between the control circuit terminal B5 and B+.
8. Verify the Q2 A/C Compressor Clutch activates. If the Q2 A/C Compressor Clutch does not activate Ignition OFF, remove the jumper wire, disconnect the harness connector at the Q2 A/C Compressor Clutch, ignition ON. Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the Q2 A/C Compressor Clutch. If the Q2 A/C Compressor Clutch activates
9. Ignition OFF, connect the X3 harness connector at the X50A Fuse Block - Underhood and disconnect the harness connector at the K20 Engine Control Module, ignition ON.
10. Verify the Q2 A/C Compressor Clutch is not activated. If the Q2 A/C Compressor Clutch is activated Ignition OFF, disconnect the X3 harness connector at the X50A Fuse Block - Underhood. Test for infinite resistance between the X3 X50A Fuse Block - Underhood control circuit terminal B4 and ground. If less than Infinite resistance, repair the short to ground on the circuit. If infinite resistance, test or replace the X50A Fuse Block - Underhood. If the Q2 A/C Compressor Clutch is not activated
11. Connect a 3 A fused jumper wire between the K20 Engine Control Module control circuit terminal for the KR29 A/C Compressor Clutch Relay and ground.
12. Verify the Q2 A/C Compressor Clutch activates. If the Q2 A/C Compressor Clutch does not activate Ignition OFF, remove the jumper wire, disconnect the X3 harness connector at the X50A Fuse Block - Underhood, ignition ON. Test for less than 1 V between the X3 X50A Fuse Block - Underhood control circuit terminal B4 and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V Test for less than 2 ohms in the control circuit end to end. If 2 ohms or greater, repair the open/high resistance in the circuit. If less than 2 ohms, test or replace the X50A Fuse Block - Underhood. If the Q2 A/C Compressor Clutch activates
13. Replace the K20 Engine Control Module.

Component Testing

Compressor Clutch Test

1. Ignition OFF, disconnect the Q2 A/C Compressor Clutch.
2. Test for 3.9 - 4.3 ohms between terminals A and B If not between 3.9 - 4.3 ohms Replace the Q2 A/C Compressor Clutch. If between 3.9 - 4.3 ohms
3. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Front Compartment Fuse Block Replacement»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
3. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for engine control module replacement, programming and setup

Symptoms - HVAC Systems - Automatic

Note. The following steps must be completed before using the symptom tables

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) before using the HVAC System Malfunction procedure 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 «Automatic HVAC Description and Operation»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__automatic-hvac-description-and-operation) .

Visual/Physical Inspection

1. Inspect for aftermarket devices which may affect the operation of the HVAC System. Refer to «Checking Aftermarket Accessories»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#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 may cause the symptom.
3. Verify the A/C compressor turns freely and is not seized.
4. Verify that the customer is using the correct key to enable personalization and is not inadvertently activating auxiliary HVAC controls.
5. The A/C compressor will not operate in cold outside air temperatures.
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 HVAC System Malfunction in order to diagnose the symptom.

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Check the following mechanical fault sources

1. Air distribution box
2. Air distribution hoses/air distribution ducts

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J43600 Air Conditioning Service Center

Note. Check for bulletins before proceeding.

1. Ignition ON.
2. Verify every applicable scan tool Switch parameter changes when pressing the appropriate switch on the A26 HVAC Controls. If any parameter does not change Replace the A26 HVAC Controls. If all parameters change
3. Verify the blower motor operates properly with the blower motor switch in each speed position. If the blower motor does not operate in each speed position Refer to «DTC B0193»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) . If the blower motor operates properly in each speed position
4. Verify the HVAC doors listed below move when pressing the appropriate switch. Driver Temperature Passenger Temperature Mode Recirculation If any HVAC door does not move Refer to «DTC B0223, B022A, B0233, B023A, B0408, or B0418»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) . If all HVAC doors move
5. Install the J43600 Air Conditioning Service Center.
6. Verify the high side pressure reading on the Air Conditioning Service Center is within 10% of the scan tool ECM A/C High Side Pressure Sensor parameter. If the reading is not within 10% Refer to «DTC P0532 or P0533»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) . If the reading is within 10%
7. Verify the A/C High Side Pressure Sensor parameter is between 269-2929 kPa (39-425 PSI). If the reading is not between 269-2929 kPa (39-425 PSI) Refer to «Air Conditioning (A/C) System Performance Test»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test) . If the reading is between 269-2929 kPa (39-425 PSI)
8. Verify the scan tool parameters listed below are within 10% of ambient temperature. Lower Left Duct Air Temperature Sensor Upper Left Duct Air Temperature Sensor Lower Right Duct Air Temperature Sensor Upper Right Duct Air Temperature Sensor A/C Evaporator Temperature Sensor If not within 10% of ambient temperature Refer to «DTC B0173, B0178, B0509, B0514 or B3933»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) . If within 10% of ambient temperature
9. Verify the scan tool parameters listed below are within 10% of actual conditions. Passenger Compartment Humidity Passenger Compartment Humidity Sensor Temperature Passenger Compartment Windshield Temperature If not within 10% of actual conditions Refer to «DTC B018A, B048C, B048F, or B1395»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) . If within 10% of actual conditions
10. Engine ON, A/C system ON.
11. Verify cool air flows from the ducts with the temperature control in the coldest position. If the air is not cool Verify the Q2 A/C Compressor Clutch is engaged. If the Q2 A/C Compressor Clutch is not engaged, refer to «Air Conditioning Compressor Malfunction»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) . If the Q2 A/C Compressor Clutch is engaged, refer to «Air Conditioning (A/C) System Performance Test»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__air-conditioning-ac-system-performance-test) . If the air is cool
12. Verify warm air flows from the ducts with the temperature control in the warmest position. If the air is not warm Refer to «Heating Performance Diagnostic»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning__heating-performance-diagnostic) . If the air is warm
13. Engine OFF, ignition ON.
14. Verify the Sunload parameter changes while covering the B10B Ambient Light/Sunload Sensor with a shop towel and changes when shining a bright light on it. If the Sunload parameter does not change Refer to «DTC B0163, B0183, or B1405»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) . If the Sunload parameter changes
15. Verify the actual inside air temperature, using a thermometer, is less than 3°C (5°F) difference from the scan tool Inside Passenger Compartment Air Temp. Sensor parameter. If greater than a 3°C (5°F) difference Refer to «DTC B0163, B0183, or B1405»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) . If less than a 3°C (5°F) difference
16. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, programming and setup

1. Perform the «Diagnostic System Check - Vehicle»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/buick/encore/i-2012-2016/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»(/buick/encore/i-2012-2016/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The A/C compressor uses a conventional belt driven magnetic clutch to engage and mechanically turn the compressor. When the A/C switch is pressed, the HVAC control module sends an A/C request message to the ECM via serial data. If specific criteria is met, the ECM then grounds the A/C compressor clutch relay control circuit, which will switch the A/C compressor clutch relay. With the relay contacts closed, battery voltage is supplied to the permanently grounded A/C compressor clutch. The A/C compressor clutch will then be activated.

The following conditions must be met in order to turn on the A/C compressor

1. Battery voltage is between 9-18 V.
2. Engine coolant temperature is less than 124°C (255°F).
3. Engine speed is greater than 600 RPM.
4. Engine speed is less than 5 500 RPM.
5. A/C high side pressure is between 269-2 929 kPa (39-425 PSI).
6. Throttle position is less than 100%.
7. Evaporator temperature is greater than 3°C (38°F).
8. ECM does not detect excessive torque load.
9. ECM does not detect insufficient idle quality.
10. The ambient temperature is above 1°C (34°F).
11. Blower motor ON

Schematic Reference

HVAC Schematics (Encore)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. «Circuit Testing»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
2. «Connector Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/buick/encore/i-2012-2016/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. Refer to HVAC System Malfunction before performing this procedure.

1. Ignition ON, press and release the A/C Switch.
2. Verify the HVAC control module scan tool A/C Switch parameter changes between Active and Inactive. If the parameter does not change Replace the A26 HVAC Controls. If the parameter changes
3. Set A/C system to coolest setting with blower ON.
4. Press and release the A/C switch several times.
5. Verify the engine control module (ECM) scan tool A/C Request Signal parameter changes between Active and Inactive. If the parameter does not change Replace the K33 HVAC Control Module. If the parameter changes
6. Verify the A/C compressor clutch engages when commanding the engine control module (ECM) A/C Relay output function On and Off with a scan tool. If the A/C compressor clutch does not engage Refer to «DTC P0645, P0646, or P0647»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic) If the A/C compressor clutch engages
7. All OK.

Perform the Diagnostic Repair Verification after completing the repair.

1. «HVAC Component Replacement Reference»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#hvac-system-automatic__hvac-component-replacement-reference)
2. «Control Module References»(/buick/encore/i-2012-2016/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for HVAC control module replacement, programming and setup

HVAC Control Module Replacement

When replacing or disconnecting the HVAC control module, it will be necessary to perform a recalibration process. When installing or reconnecting the HVAC control module, be sure to perform the following

Preferred Method (with Scan Tool)

Note. Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

1. Ignition OFF.
2. Disconnect the scan tool.
3. Install/connect the HVAC control module.
4. Connect all previously disconnected components.
5. Start the vehicle.
6. With the scan tool, initiate the HVAC Actuators Learn feature of the HVAC control module Special Functions menu.
7. Operate system and verify that no DTCs have set as current DTCs.
8. If DTC B101E 4B is set after attempting the actuator recalibration procedure, perform the following: Verify which actuator does not have a scan tool learn status parameter status of complete. Verify the unlearned actuator is physically rotating - A common cause of DTC B101E 4B is an actuator that is electrically OK but fails to physically rotate (e.g. stripped gears). If the unlearned actuator is not physically rotating, replace the actuator, otherwise replace the HVAC control module.

Alternate Method (without Scan Tool)

1. Clear all DTCs.
2. Ignition OFF.
3. Install/connect the HVAC control module.
4. Connect all previously disconnected components.
5. Remove the HVAC control module fuse for a minimum of 10 s.
6. Install the HVAC control module fuse.
7. Start the vehicle.
8. Wait 40 s for the HVAC control module to self-calibrate.

Actuator Replacement

When replacing an HVAC actuator it will be necessary to allow the HVAC control module to perform a recalibration process. When installing an HVAC actuator be sure to perform one of the following

Preferred Method (with Scan Tool)

1. Clear all DTCs.
2. Ignition OFF.
3. Install the HVAC actuator.
4. Connect all previously disconnected components.
5. Start the vehicle.
6. With the scan tool, initiate the HVAC Actuators Relearn feature of the HVAC control module Special Functions menu.
7. Operate system and verify that no DTCs have set as current DTCs.
8. If DTC B101E 4B is set after attempting the actuator recalibration procedure, perform the following: Verify which actuator does not have a scan tool learn status parameter status of complete. Verify the unlearned actuator is physically rotating - A common cause of DTC B101E 4B is an actuator that is electrically OK but fails to physically rotate (e.g. stripped gears). If the unlearned actuator is not physically rotating, replace the actuator, otherwise replace the HVAC control module.

Alternate Method (without Scan Tool)

1. Clear all DTCs.
2. Ignition OFF.
3. Install the HVAC actuator.
4. Connect all previously disconnected components.
5. Remove the HVAC control module fuse for a minimum of 10 s.
6. Install the HVAC control module fuse.
7. Start the vehicle.
8. Wait 40 s for the HVAC control module to self-calibrate.

Scheme 71

Heater and Air Conditioning Control Replacement

Scheme 72

Heater and Air Conditioning Remote Control Replacement

Scheme 73

Air Inlet Valve Actuator Replacement - Left Side (With CJ2)

Scheme 74

Air Inlet Valve Actuator Replacement - Right Side (With CJ2)

Scheme 75

Mode Control Cam Actuator Replacement

Scheme 76

Mode Control Cam Replacement

Alignment Procedure

1. Remove the heater and air conditioning evaporator and blower module assembly (HVAC). Refer to «Heater and Air Conditioning Evaporator and Blower Module Removal and Installation»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
2. Remove the mode control cam. Refer to «Mode Control Cam Replacement (C67)»(/buick/encore/i-2012-2016/remont/manual-hvac-system/#hvac-system-manual) , «Mode Control Cam Replacement (C60)»(/buick/encore/i-2012-2016/remont/manual-hvac-system/#hvac-system-manual) .
3. Inspect the mode valve levers and internal vent valve operation prior to installing the new mode control cam assembly.
4. Replace the components affecting the proper operation of the vent valves.
5. Rotate the defrost valve lever (1), vent valve lever (2), and heater valve lever (3) to the position as shown.
6. Using a small brush, apply a lithium based lubricant to the channels of the heater cam, and the mode cam where the levers travel.
7. Install the heater cam (1) aligning the channel on the back side of the heater cam with the heater valve lever pin (2).
8. Inspect the heater valve lever pin (2) is visible in the heater cam (1) inspection window indicated by the arrow.
9. Rotate the heater cam (1) counter clockwise, position the larger heater cam female tooth gear as indicated by the arrow.
10. Install the mode cam (2) aligning the larger male tooth with the heater cam (1) larger female tooth indicated by the arrows, while aligning the channels on the back side of the mode cam (2) with the defroster valve lever pin (3), and the vent valve lever pin (4). The pins should be visible through the inspection windows.
11. Verify that the large male tooth on the mode control cam (2) is aligned with the large female tooth on the heater cam (1).
12. Re-install the heater and air conditioning evaporator and blower module assembly (HVAC). Refer to «Heater and Air Conditioning Evaporator and Blower Module Removal and Installation»(/buick/encore/i-2012-2016/remont/automatic-hvac-system/#heating-ventilation-and-air-conditioning) .
13. Verify for proper operation of the HVAC system.

Scheme 77

Inside Air Moisture and Windshield Temperature Sensor Replacement (With CJ2)

Scheme 78

Sun Load Temperature Sensor Replacement

Scheme 79

Sun Load Temperature Sensor Bezel Replacement (Trax)

Scheme 80

Sun Load Temperature Sensor Bezel Replacement (Encore)

Automatic HVAC Description and Operation

The air temperature and the air delivery description and operation are divided into five areas

1. HVAC Control Components
2. Air Speed
3. Air Delivery
4. Heating and A/C Operation
5. Recirculation Operation

HVAC Control Components

HVAC Controls

The HVAC controls interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The air temperature and mode doors are controlled by cables. The recirculation actuator is electrically controlled.

The HVAC control module supports the following features

Evaporator Temperature Sensor

The evaporator temperature sensor is a two-wire negative temperature co-efficient thermistor. The sensor operates within a temperature range of -40 to +85°C (-40 to +185°F). The sensor is installed at the evaporator and measures its temperature. If the temperature drops under 1°C (34°F), the A/C compressor will be commanded off in order to prevent icing of the evaporator.

A/C Refrigerant Pressure Sensor

The engine control module (ECM) monitors the high side refrigerant pressure through the signal circuit of the A/C refrigerant pressure sensor. The ECM supplies a 5V reference and a low reference to the sensor. Changes in the A/C refrigerant pressure cause the sensor signal to the ECM to vary. When the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low. When pressure is high, the ECM commands the cooling fans on. When pressure is too high or too low, the ECM will inhibit activation of the A/C compressor.

A/C Compressor

The A/C compressor is belt driven and operates when the magnetic clutch is engaged. When the A/C switch is pressed, a serial data message is sent from the HVAC control module to the ECM indicating the A/C request. If the ECM determines that conditions are acceptable for A/C operation, it will apply ground to the A/C compressor clutch relay control circuit, energizing the A/C compressor clutch relay. With the relay contacts closed, battery voltage is applied through the control circuit to the A/C compressor clutch. The A/C compressor clutch will engage and the compressor will operate.

Windshield Temperature and Inside Moisture Sensor

The windshield temperature and inside moisture sensor includes the relative humidity sensor, windshield temperature sensor and humidity sensing element temperature sensor.

This sensor assembly provides information about

1. Relative humidity level at windshield (compartment side)
2. Temperature of the windshield inside (compartment side)
3. Temperature of the humidity sensor element

The relative humidity sensor measures the relative humidity of the compartment side of the windshield. It also detects the temperature of the windshield surface on the passenger compartment side. Both values are used as control inputs for the HVAC control module application to calculate the fog risk on windshield compartment side. The sensor will also enable partial recirculation mode in order to improve heat-up performance of the passenger compartment under cold ambient temperature conditions without the risk of mist build-up on the windshield. The humidity sensor element temperature sensor supplies the temperature of the humidity sensor element.

Ambient Light/Sunload Sensor

The ambient light/sunload sensor includes the sunload sensor and passenger compartment temperature sensor.

This sensor assembly provides information about

1. Sun heat intensity
2. Passenger compartment temperature

The passenger compartment temperature sensor is a negative temperature co-efficient thermistor. A signal and low reference circuit enables the sensor to operate. As the air temperature increases, the sensor resistance decreases. The sensor signal varies between 0-5 V.

The sunload sensor provides a measurement of sun intensity. The sensor operates using a low reference, pulsed supply voltage, and signal circuits. A 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.

Blower Motor Control

The blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the blower motor. The HVAC control module provides a low side pulse width modulation (PWM) signal to the blower motor control processor via the blower motor speed control circuit. As the requested blower speed increases, the HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the HVAC control module decreases the amount of time that the signal is modulated to ground.

Air Delivery

The HVAC control assembly controls the distribution of air by the use of recirculation actuator and the mechanically controlled mode door. The modes that may be selected are

1. Defrost - Air flow is directed at the windshield
2. Defog - Air flow is split between the windshield and floor
3. Vent - Air flow is directed to the vents located in the instrument panel
4. Bi-Level - Air flow is split between the instrument panel vents and the floor vents
5. Floor - Air flow is directed to the floor

The desired air distribution mode can be selected with the air distribution knob at the HVAC control assembly. Depending on the position of the flap, air is distributed through various ducts leading to the outlets in the instrument panel. When the defrost position is selected, the HVAC control assembly will command the recirculation actuator to outside air, reducing window fogging.

Heating and A/C Operation

The purpose of the heating and A/C system is to provide heated or cooled air to the interior of the vehicle. The A/C system will also remove humidity from the interior and reduce windshield fogging. Regardless of the temperature setting, the following can affect the rate that the HVAC system can achieve the desired temperature

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

When the A/C switch is pressed, an A/C request serial data message to the ECM. If the ECM determines that conditions are acceptable for A/C operation, it will ground the A/C compressor clutch relay control circuit, energizing the A/C compressor clutch relay. With the relay contacts closed, battery voltage is supplied to the A/C compressor clutch. The A/C compressor clutch will engage and the compressor will operate.

The following conditions must be met in order to activate the A/C compressor

1. Battery voltage is between 9-18 V
2. Engine coolant temperature is less than 120°C (248 °F)
3. Engine speed is greater than 600 RPM
4. Engine speed is less than 6200 RPM
5. A/C high side pressure is between 220-3100 kPa (32-450 PSI)
6. Throttle position is less than 95%
7. Evaporator temperature is greater than 3°C (38°F)
8. ECM does not detect an unacceptable torque load
9. ECM does not detect insufficient idle quality

The temperature door controls the temperature of the air entering the passenger compartment. Air entering the passenger compartment passes through the heater core and/or the evaporator core. The position of the temperature door determines how much air passes through the heater or evaporator core. As the temperature control is moved to a hotter setting, the temperature door will direct more air through the heater core. As the temperature control is moved to a cooler setting, more air will be passed through the evaporator core.

Recirculation Operation

Recirculation Actuator

The recirculation actuator is a two-wire bi-directional electric motor. There are two control circuits that allow actuator operation. The control circuits use either a 0 or 12 V value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 V. To move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 V. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction.

See also:
• Air Conditioning Clutch Assembly Replacement (LUJ, LUV)
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Symptom Byte List
• WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Front Compartment Fuse Block Replacement
• Checking Aftermarket Accessories
• Air Conditioning (A/C) System Performance Test
• Heating Performance Diagnostic
• Radio Control Assembly Replacement
• HVAC System Control Module Programming and Setup
• Actuator Recalibration (C67)
• Floor Front Air Outlet Duct Replacement - Left Side (Trax)
• Instrument Panel Knee Bolster Replacement (Encore)
• Battery Negative Cable Disconnection and Connection
• Steering Column Replacement (Mexico, N40)
• Fastener Caution
• Windshield Outside Moisture Sensor Cover Replacement (Encore)
• Air Inlet Valve Actuator Replacement - Left Side (With CJ2)
• Automatic HVAC Description and Operation
• HVAC Component Replacement Reference