HVAC System - Automatic: Diagnosis GMC Sierra III

Diagnostic Code Index

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

Diagnostic Fault Information

Conditions for Running the DTC

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

Conditions for Setting the DTC

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.

Action Taken When the DTC Sets

The system operates using a default value.

Conditions for Clearing the DTC

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

Circuit/System Testing

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. Ignition ON.
4. 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)
5. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 6.
6. Verify the scan tool parameter Passenger Compartment Air Temperature (Unfiltered) parameter is greater than 113°C (235°F). If 113°C (235°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 113°C (235°F)
7. Test or replace the B10B Ambient Light/Sunload Sensor.

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

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.

1. Ignition OFF, cut both temperature sensor wires approximately 8 cm (3 in) from the appropriate temperature sensor.
2. Ignition OFF and all vehicle systems OFF. It may take up to 10 min for all vehicle systems to power down.
3. Test for less than 10 ohms between the low reference circuit 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
4. Ignition ON.
5. 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 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, replace the K33 HVAC Control Module. If -37°C (-35°F) or less
6. Install a 3 A fused jumper wire between the signal circuit and the low reference circuit.
7. 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 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 77°C (170°F) or greater
8. Test or replace the temperature sensor.

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

1. Ignition ON
2. The HVAC Control Module is ON.

B0183 02

The input signal is out of range. The voltage is less than 0.1 V.

B0183 05

The input signal is out of range. The voltage is greater than 4.9 V.

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 0 W/m 2 as intensity.

The condition for setting the DTC is no longer present.

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. Ignition ON.
4. 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 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
5. Test or replace the B10B Ambient Light/Sunload Sensor.
6. Verify DTC B0183 did not reset. If DTC B0183 did reset Replace the K33 HVAC Control Module. If DTC B0183 did not reset
7. All OK

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

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

The current design of this motor does not allow for bench testing. The motor will not operate by simply applying power and ground.

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

Check for Preliminary Information or Technical Service Bulletins.

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M8 Blower Motor. 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 6 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 1 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 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the M8 Blower Motor. If the test lamp illuminates
5. Remove the test lamp, ignition ON.
6. Test for 6.6-7.8 V between the control circuit terminal 2 and B+. If greater than 7.8 V Ignition OFF, disconnect the X2 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 less than 6.6 V Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module. 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 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 between 6.6-7.8 V
7. Test or replace the M8 Blower Motor.

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

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

B0228 02, B0413 02, B0423 02 or B374A 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.

B0228 05, B0413 05, B0423 05 or B374A 05

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 sensor reference voltage out of range. The reference voltage is less than 0.1 V for more than 50 ms.

B1395 07

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

B1395

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

B0228, B0413, B0423 or B374A

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

The condition for setting the DTC is no longer present.

DTC B1395

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 X2, X3 and X4 harness connectors at the K33 HVAC Control Module.
3. Test for infinite resistance between the K33 HVAC Control Module 5 V reference circuit terminal 17 X2 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 5 V reference terminal 17 X2 and ground. If 1 V or greater Repair the short to voltage on the circuit. If less than 1 V
6. Clear all DTCs.
7. Ignition OFF, connect the X2, X3 and X4 harness connectors at the K33 HVAC Control Module, ignition ON.
8. Verify DTC B1395 is not set. If the DTC is set. Replace the K33 HVAC Control Module. If the DTC is not set.
9. Verify DTC B1395 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 after connecting one of the components Replace the component that was connected immediately before the DTC set. If the DTC does not set
10. All OK.

DTC B0228, B0413, B0423 or B374A

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate door actuator. 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 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 3 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 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 connector 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. Test for 4.8-5.2 V between the signal circuit terminal 2 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 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
6. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module, ignition ON.
7. Test for less than 1 V between each control circuit listed below and ground: Actuator terminal 5 Actuator terminal 6 If 1 V or greater Repair the short to voltage on the circuit. If less than 1 V
8. Test for infinite resistance between each control circuit listed below and ground: Actuator terminal 5 Actuator terminal 6 If less than infinite resistance Repair the short to ground on the circuit. If infinite resistance
9. Test for infinite resistance between the control circuits listed below: Actuator terminal 5 Actuator terminal 6 If less than infinite resistance Repair the short on the circuit. If infinite resistance
10. Test for less than 2 ohms in each control circuit end to end. If 2 ohms or greater Repair the open/high resistance in the circuit. If less than 2 ohms
11. Test or replace the actuator.
12. Verify the DTC or symptom is corrected while operating the HVAC system under the Conditions for Running the DTC. If the DTC or symptom is not corrected Replace the K33 HVAC Control Module. If the DTC or symptom is corrected
13. All OK.

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

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

B393B 04

A PWM greater than 10% is sent but no current is read back.

B393B 0B

Measured current is above threshold of 815 mA.

B393B 04

The A/C compressor is disabled.

B393B 0B

1. The A/C compressor is disabled.
2. Output will be switched off for hardware protection.

The condition for setting the DTC is no longer present.

1. Ignition OFF, disconnect the harness connector at the Q46 A/C Compressor Solenoid Valve and disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON.
2. Test for less than 1 V between each control circuit listed below and ground: Solenoid terminal 1 Solenoid terminal 2 If 1 V or greater Repair the short to voltage on the circuit. If less than 1 V
3. Ignition OFF.
4. Test for infinite resistance between each control circuit listed below and ground: Solenoid terminal 1 Solenoid terminal 2 If less than infinite resistance Repair the short to ground on the circuit. If infinite resistance
5. Test for infinite resistance between the control circuits listed below: Solenoid terminal 1 Solenoid terminal 2 If less than infinite resistance Repair the short on the circuit. If infinite resistance
6. Test for less than 2 ohms in each control circuit end to end. If 2 ohms or greater Repair the open/high resistance in the circuit. If less than 2 ohms
7. Test or replace the Q46 A/C Compressor Solenoid Valve.
8. Verify the DTC or symptom is corrected while operating the HVAC system under the Conditions for Running the DTC. If the DTC or symptom is not corrected Replace the K33 HVAC Control Module. If the DTC or symptom is corrected
9. All OK.

Component Testing

Static Test

1. Ignition OFF, disconnect the harness connector at the Q46 A/C Compressor Solenoid Valve.
2. Test for 7-15 ohms between B+ terminal 2 and control terminal 1. If less than 7 ohms or greater than 15 ohms Replace the Q46 A/C Compressor Solenoid Valve. If between 7-15 ohms
3. Test for infinite resistance between each terminal and the Q46 A/C Compressor Solenoid Valve housing/case. If less than infinite resistance Replace the Q46 A/C Compressor Solenoid Valve. If infinite resistance
4. All OK.

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

1. The ignition is ON
2. The 12 V battery voltage is greater than or equal to 10.2 V.

P0071

During the first 20 seconds of run time after the 1 hour soaking period, the difference between the outside air temperature and the engine intake air temperature is greater than 30°C(86°F).

P0072

The ECM detects the sensor signal is more than 88°C (190°F).

P0073

The ECM detects the sensor signal is less than -40°C (-40°F).

P0074

The ECM detects an unrealistic signal variance.

1. DTC P0071-P0074 are B type DTCs.
2. The DIC will display SERVICE A/C SYSTEM.
3. The system operates using a default value.

The DTC will become history if the ECM no longer detects a malfunction.

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B9 Ambient Air Temperature 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 2 and ground. If 10 ohms or greater Ignition OFF, disconnect the X2 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. Verify the scan tool Ambient Air Temperature parameter is less than-39°C (-38°F). If -39°C (-38°F) or greater Ignition OFF, disconnect the X1 harness connector at the K20 Engine Control Module. Test for infinite resistance between the signal circuit terminal 1 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K20 Engine Control Module. If less than -39°C (-38°F)
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
6. Verify the scan tool Ambient Air Temperature parameter is greater than 88°C (190°F). If 88°C (190°F) or less Ignition OFF, remove the jumper wire and disconnect the X1 harness connector at the K20 Engine 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 K20 Engine Control Module. If less than 88°C (190°F)
7. Test or replace the B9 Ambient Air Temperature Sensor.

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of the diagnostic category.

1. Engine is running.
2. Any of the conditions for setting the DTC are met for 15 seconds.
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.

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 ECM 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 engine control module 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.

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

1. Engine is running.
2. The HVAC control module is ON.
3. The A/C switch is active.

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. The A/C compressor solenoid is commanded to 0% displacement. This causes warm air from the ducts, even with unwanted clutch engagement.

P0647

The A/C compressor is inoperative.

The condition for setting the DTC is no longer present.

1. Ignition OFF, disconnect the KR29 A/C Compressor Clutch Relay, ignition ON.
2. Verify a test lamp illuminates between the B+ circuit terminal 30 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 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance Disconnect the harness connector at the Q2 A/C Compressor Clutch. Test for infinite resistance between the control circuit terminal 87 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, test or replace the Q2 A/C Compressor Clutch. If the test lamp illuminates
3. Ignition ON.
4. Verify a test lamp illuminates between the ignition circuit terminal 86 and ground. If the test lamp does not illuminate Refer to «Power Mode Mismatch»(ref-651023-S29861396702014081900000) . If the test lamp illuminates
5. Connect a test lamp between the ignition circuit terminal 86 and the control circuit terminal 85.
6. Verify the test lamp turns ON and OFF when commanding the ECM A/C Compressor Clutch Relay On and Off with a scan tool. If the test lamp is always OFF Ignition OFF, remove the test lamp and disconnect the harness connector at the K20 Engine 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 in the circuit. If less than 2 ohms, replace the K20 Engine Control Module. If the test lamp is always ON Ignition OFF, remove the test lamp and disconnect the harness connector at the K20 Engine 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 K20 Engine Control Module. If the test lamp turns ON and OFF
7. Verify a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates Repair the short to voltage on the circuit. If the test lamp does not illuminate
8. 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.
9. Test for less than 10 ohms between the ground circuit terminal 1 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
10. Connect the harness connector at the Q2 A/C Compressor Clutch.
11. Ignition ON, connect a 10 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
12. Verify the Q2 A/C Compressor Clutch is engaged. If the Q2 A/C Compressor Clutch does not engage Ignition OFF, disconnect the harness connector at the Q2 A/C Compressor Clutch. 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 is engaged
13. Test or replace the KR29 A/C Compressor Clutch Relay.

1. Ignition OFF, disconnect the KR29 A/C Compressor Clutch Relay.
2. Test for 60-180 ohms between terminals 85 and 86. If not between 60-180 ohms Replace the KR29 A/C Compressor Clutch Relay. If between 60-180 ohms
3. Test for infinite resistance between the terminals listed below: 30 and 86 30 and 87 30 and 85 85 and 87 If less than infinite resistance Replace the KR29 A/C Compressor Clutch Relay. If infinite resistance
4. Install a 15 A fused jumper wire between terminal 86 and 12 V. Install a jumper wire between terminal 85 and ground.
5. Test for less than 2 ohms between terminals 30 and 87. If 2 ohms or greater Replace the KR29 A/C Compressor Clutch Relay. If less than 2 ohms
6. All OK.

Visual/Physical Inspection

1. Inspect for aftermarket devices which may affect the operation of the HVAC System. Refer to «Checking Aftermarket Accessories»(ref-651023-S10146574172014081900000) .
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

Symptom List

Refer to HVAC System Malfunction in order to diagnose the symptom.

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

Check the following mechanical fault sources

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

1. Perform the «Diagnostic System Check - Vehicle»(ref-650999-S38140870152014081900000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-650999-S18942452582014081900000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-650999-S34767258932014081900000) provides an overview of each diagnostic category.

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 is ON.