Air Conditioning Compressor Malfunction
Diagnostic Instructions
Diagnostic Fault Information
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Circuit
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Short to Ground
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Open/High Resistance
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Short to Voltage
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Signal Performance
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A/C Compressor B+
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B393B 04
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B393B 04
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--
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--
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A/C Compressor Control
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B393B 04
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B393B 04
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B393B 0B
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1
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1. A/C Compressor Malfunction
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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.
Diagnostic Aids
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) |
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Manual HVAC Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
Note: Before executing
Circuit/System Testing, all conditions shown in Diagnostic Aids
must be met.
- Ignition ON, press and release the A/C Switch. Verify
the scan tool A/C Switch parameter changes between Active and
Inactive.
| ⇒ |
If not the specified value, replace the
A26 HVAC Control. |
- 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.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
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