HVAC Systems - Automatic: Diagnosis Pontiac G6 I

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Scan Tool Output Controls

PCM/ECM Scan Tool Output Controls

Scan Tool Data List

Use the Scan Tool Data Display Values and Definitions in order to assist in diagnosing the HVAC. Compare the vehicles actual scan tool data with the typical data display value table information. Use the data information in order to aid in understanding the nature of the concern when the vehicle does not match with the typical data display values.

The scan tool data values were taken from a known good vehicle under the following conditions

1. The ignition switch is in the ON position.
2. The engine is running at idle.
3. The vehicle is in PARK.
4. The doors are closed.
5. The windows are closed.
6. The A/C is ON.
7. The ambient air temperatures are at 22-27°C (70-80°F).

BCM

PCM

ECM

Circuit Description

The HVAC control module monitors air temperature through air temperature sensors. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low. The HVAC control module requests A/C compressor clutch engagement and controls the appropriate mode and air temperature actuator door positions in order to maintain the selected air temperature on the HVAC control module.

The inside air temperature sensor is contained within the HVAC control module. The replacement of the inside air temperature sensor involves the replacement of the HVAC control module. The inside air temperature sensor provides the HVAC control module with the temperature of the air drawn through an aspirator from the passenger compartment across a sensor. A reference voltage is supplied to the sensor thermistor and the HVAC control module determines the voltage drop across that device which is proportional to temperature. As the air temperature increases, the resistance decreases and the voltage signal decreases. As the air temperature decreases, the resistance increases and the voltage signal increases.

Output air temperature sensor 1 circuit refers to the A/C upper duct air temperature sensor.

Output air temperature sensor 2 circuit refers to the heater lower duct air temperature sensor.

Passenger compartment temperature sensor 1 circuit refers to the inside air temperature sensor.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC B0164 Passenger Compartment Temperature Sensor Circuit Range/Performance
2. DTC B0174 Output Air Temperature Sensor 1 Circuit
3. DTC B0179 Output Air Temperature Sensor 2 Circuit

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .

The HVAC control module monitors the signal circuit of the appropriate duct or inside air temperature sensor for the following conditions

DTC B0164, B0174 or B0179

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Clearing the MIL/DTC

1. The DTC will become history if the HVAC control module no longer detects a failure.
2. The history DTC will clear after 40 fault-free ignition cycles.
3. The DTC can be cleared with a scan tool.

Diagnostic Aids

1. Inspect the actuator door and actuator for the following conditions: A misaligned air temperature actuator-Refer to «Air Temperature Actuator Replacement»(ref-243034-S01116829292006082100000) . Broken or binding linkages or actuator door Obstruction that prevents the actuator door from operating within its full range of motion Missing seals to the actuator door Misaligned seals to the actuator door
2. Refer to «Testing for Intermittent Conditions and Poor Connections»(ref-242973-S38322986792006082100000) .

The powertrain control module (PCM) monitors the high side refrigerant pressure through the A/C refrigerant pressure sensor. The PCM 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 PCM 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 PCM commands the cooling fans ON. When pressure is too high or too low, the PCM will not allow the A/C compressor clutch to engage.

This diagnostic procedure supports the following DTCs

1. DTC P0530 Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit
2. DTC P0532 Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit Low Voltage
3. DTC P0533 Air Conditioning (A/C) Refrigerant Pressure Sensor Circuit High Voltage

The ignition is ON.

Conditions for Setting the DTC

All of the following conditions exist for 15 seconds.

1. The PCM detects that the A/C pressure is 9 psi (0.2 volt) or less.
2. The PCM detects that the A/C pressure is more than 453 psi (4.92 volts).
3. The PCM detects a too low or too high signal on the A/C refrigerant pressure sensor signal circuit.

Action Taken When the DTC Sets

1. The PCM will not illuminate the malfunction indicator lamp (MIL).
2. The PCM stores the Failure Records.
3. The A/C compressor clutch is disabled.

Conditions for Clearing the DTC

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

Test the following conditions

1. Visually inspect the sensor for contamination or damage.
2. Inspect for the following that may affect the sensor accuracy: A malfunction within the refrigerant system causing high pressure Visually inspect the A/C components and lines for damage.
3. Refer to «Testing for Intermittent Conditions and Poor Connections»(ref-242973-S38322986792006082100000) .

Ignition voltage is supplied directly to the A/C compressor clutch relay. The powertrain control module (PCM) controls the relay by grounding the A/C clutch relay control circuit via an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. The driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be near 0 volts. When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage. If the fault detection circuit senses a voltage other than what is expected, this DTC will set.

The PCM will monitor the control circuit for the following

1. A short to ground
2. A short to voltage
3. An open circuit
4. An open relay coil
5. An internally shorted or excessively low resistance relay coil

When the PCM detects any of the above malfunctions, this DTC is set and the affected driver is disabled.

This diagnostic procedure supports the following DTCs

1. DTC P0645 Air Conditioning A/C Clutch Relay Control Circuit
2. DTC P0646 Air Conditioning A/C Clutch Relay Control Circuit Low Voltage
3. DTC P0647 Air Conditioning A/C Clutch Relay Control Circuit High voltage

This vehicle has DTCs which include DTC Symptoms, refer to Symptoms - Vehicle .

1. The ignition voltage is between 9-18 volts.
2. The engine speed is more than 80 RPM.
3. The PCM driver transitions from ON to OFF or from OFF to ON.

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to «Checking Aftermarket Accessories»(ref-242973-S33559790262006082100000) in Wiring Systems.
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»(ref-243034-S25014267742006082100000) .
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

Symptom List

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

1. «HVAC Compressor Clutch Does Not Engage»(ref-243034-S13886701682006082100000)
2. «HVAC Compressor Clutch Does Not Disengage»(ref-243034-S02078969972006082100000)
3. «Blower Motor Always On»(ref-243034-S39067252492006082100000)
4. «Blower Motor Inoperative»(ref-243034-S39328593052006082100000)
5. «Blower Motor Malfunction»(ref-243034-S26450524552006082100000)
6. «Too Hot in Vehicle»(ref-243034-S23802200162006082100000)
7. «Too Cold in Vehicle»(ref-243034-S35952193952006082100000)
8. «Air Delivery Improper»(ref-243034-S37503654102006082100000)
9. «Air Recirculation Malfunction»(ref-243034-S22544936332006082100000)
10. «Leak Testing»(ref-243028-S40223582802006082100000) in Heating, Ventilation and Air Conditioning
11. «Defrosting Insufficient»(ref-243028-S24572487322006082100000) in Heating, Ventilation and Air Conditioning
12. «Noise Diagnosis - Blower Motor»(ref-243028-S18502093082006082100000) in Heating, Ventilation and Air Conditioning
13. «Noise Diagnosis - Air Conditioning (A/C) System»(ref-243028-S38780539772006082100000) in Heating, Ventilation and Air Conditioning
14. «Odor Diagnosis»(ref-243028-S08638293762006082100000) in Heating, Ventilation and Air Conditioning
15. «Noise Diagnosis - HVAC Module»(ref-243028-S28640199112006082100000) in Heating, Ventilation and Air Conditioning

1. The condition may be intermittent. Refer to «Testing for Intermittent Conditions and Poor Connections»(ref-242973-S38322986792006082100000) .
2. Ensure that the panel vents are in the OPEN position for proper diagnosis.
3. Inspect the air delivery system for the following conditions: An obstruction to the airflow Air leaks Misaligned air ducts Broken or binding linkages or doors

Air Delivery Improper

1. The condition may be intermittent. Refer to «Testing for Intermittent Conditions and Poor Connections»(ref-242973-S38322986792006082100000) .
2. Inspect the air delivery system for the following conditions: An obstruction to the airflow Air leaks Misaligned air ducts Broken or binding linkages or doors