Air Conditioning Compressor Malfunction (LAU, LBR, LBS, LDK, or LHU)
|
|
Air Conditioning Compressor Malfunction (LAU, LBR, LBS, LDK, or LHU)
|
|
Diagnostic Fault Information
|
|
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
A/C Compressor B+
|
B393B 04
|
B393B 04
|
-
|
-
|
A/C Compressor Control
|
B393B 04
|
B393B 04
|
B393B 0B
|
1
|
1. A/C Compressor Malfunction
|
|
Circuit/System Description
|
The HVAC control module supplies battery voltage to the A/C compressor. When the A/C switch is pressed, the HVAC control module provides a pulse width modulation (PWM) signal to the A/C compressor in order to command the performance of the A/C compressor. The performance of the A/C compressor is regulated according to adjusted interior temperature on the basis of characteristic lines. Therefore the HVAC control module grounds the A/C compressor with the PWM signal.
The following conditions must be met in order for the HVAC control module to turn on the A/C compressor:
|
•
|
Battery voltage is between 9-18 V.
|
|
•
|
Engine coolant temperature is less than 124°C (255°F).
|
|
•
|
Engine speed is greater than 600 rpm.
|
|
•
|
Engine speed is less than 5 500 rpm.
|
|
•
|
A/C high side pressure is between 269-2,929 kPa (39-425 psi).
|
|
•
|
Throttle position is less than 100%.
|
|
•
|
Evaporator temperature is greater than 3°C (38°F).
|
|
•
|
ECM does not detect immoderate torque load.
|
|
•
|
ECM does not detect insufficient idle quality.
|
|
•
|
The ambient temperature is above 1°C (34°F).
|
Schematic Reference
HVAC Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Automatic HVAC Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
for scan tool information
|
Note
|
|
Before executing Circuit/System Testing, all conditions shown in Diagnostic Aids must be met.
|
|
1.
|
Ignition ON, press and release the POWER switch. Verify the scan tool Front HVAC System Status parameter changes between Off and On.
|
|
2.
|
If not the specified value, replace the A20 Radio/HVAC Controls.
|
|
3.
|
Ignition ON, press and release the A/C Switch. Verify the scan tool A/C Switch parameter changes between Active and Inactive.
|
|
4.
|
If not the specified value, replace the A20 Radio/HVAC Controls.
|
|
5.
|
Press and release the AUTO Switch. Verify the scan tool Auto HVAC Button parameter changes between Active and Inactive.
|
|
6.
|
If not the specified value, replace the A20 Radio/HVAC Controls.
|
|
7.
|
If all circuits test normal, replace the K33 HVAC Control Module and verify the Q46 Air Conditioning Compressor Valve can be activated and deactivated. If the Q46 Air Conditioning Compressor Valve cannot be activated or deactivated, replace the Q46 Air Conditioning Compressor Valve.
|
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
