Auxiliary Air Temperature Malfunction
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Auxiliary Air Temperature Malfunction
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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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Stepper Motors 12 V Reference
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B023A 02, B0223 06, B022A 06, B0233 06, B0408 06, B0418 06, B0428 06, B3531 06
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B0223 06, B022A 06, B0233 06, B0408 06, B0418 06, B0428 06, B3531 06
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-
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-
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Rear Air Temperature Actuator Control 1
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B0428 06
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B0428 06
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B0428 01
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1
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Rear Air Temperature Actuator Control 2
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B0428 06
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B0428 06
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B0428 01
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1
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Rear Air Temperature Actuator Control 3
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B0428 06
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B0428 06
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B0428 01
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1
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Rear Air Temperature Actuator Control 3
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B0428 06
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B0428 06
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B0428 01
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1
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1. Auxiliary Air Temperature Malfunction
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Circuit/System Description
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With the temperature switches at the Radio/HVAC control - auxiliary, the desired air temperature flap position can be put in. The selected value is sent to the HVAC control module via the LIN-Bus. The HVAC control module supplies a 12 V reference voltage to the stepper motor and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motor puts the mixed air flap into the calculated position, in order to reach the selected temperature.
Check the following mechanical fault sources:
•
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Air distribution hoses/air distribution ducts
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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
Circuit/System Verification
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Measure actual temperature using a thermometer at each of the duct temperature sensors. Compare this value to the appropriate scan tool Duct Actual parameter. The measured temperature should be within 5°C (9°F) difference of appropriate Duct Actual parameter value.
If not within the specified range, refer to
DTC B0173, B0178, B0509, B0514, B0519, B3583, or B3933
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1.
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Ignition ON, press and release the rear temperature increase switch. Verify the scan tool Rear Temperature Setting parameter. The reading should correspond to the selected temperature.
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2.
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If not the specified value, replace the A21 Radio/HVAC Controls - Auxiliary.
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3.
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Press and release the rear temperature decrease switch. Verify the scan tool Rear Temperature Setting parameter. The reading should correspond to the selected temperature.
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4.
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If not the specified value, replace the A21 Radio/HVAC Controls - Auxiliary.
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5.
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Press and release the ZONE Switch. Verify the scan tool MULTIZONE Switch parameter changes between Active and Inactive.
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6.
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If not the specified value, replace the A20 Radio/HVAC Controls.
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7.
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If all circuits test normal, replace the M6B Air Temperature Door Actuator - Auxiliary and verify the M6B Air Temperature Door Actuator - Auxiliary can be put into all positions. If the M6B Air Temperature Door Actuator - Auxiliary cannot be put into all positions, replace the K33 HVAC Control Module.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.