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Home >> Audi >> 2003 >> Allroad Quattro (4BH) V8-4.2L (BAS) >> Repair and Diagnosis >> Heating and Air Conditioning >> Compressor HVAC >> Testing and Inspection
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Compressor HVAC: Testing and Inspection




A/C compressor shut-off, checking


NOTE:
The A/C compressor signal informs the engine control module that the compressor will be switched on in 140 ms. The engine control module can send a signal via the same wire to shut off the A/C compressor

The engine control module will shut off the A/C compressor in the following circumstances:
- In emergency running mode (back-up)
- When a signal is received from the Transmission Control Module (TCM) (kickdown switch)
- When the function "Basic Setting" function is initiated (function 04)

Test conditions
- Climate Control functioning properly
- No malfunctions recorded in DTC memory of engine control module
- Interior temperature greater than + 15 ° C

- Connect Vehicle Diagnostic, Testing and Information System VAS5051 or VAG 1551 Scan Tool and select engine electronics control module by entering address word "01", Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1551/ VAS 5051 Scan Tool" Testing and Inspection .When doing this the engine must be idling.

Indicated on display


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select function "Read Measuring Value Block" and confirm entry with -Q- button.

Indicated on display


Read Measuring Value Block
Input display group number XXX


- Press buttons -0-, -5- and -0- to select "Display Group 050" and confirm entry with -Q- button.

Indicated on display


Read Measuring Value Block 50 ->
Input display group number XXX

- Check A/C compressor shut-off (display field 4).







- Switch on A/C by pressing the "Auto" button. The compressor should run (display field 4).
- Set A/C to maximum hot/cold air output (display field 3).







- Switch off compressor with controls on A/C control head, for this press "Econ" button.

Specification for display field 4: The display should change from "Compr.ON" to "Compr.OFF" (Compressor shut off).

If the readout in display field 4 is not as described:
- Switch ignition off.
- Connect VAG 1598/31 test box to wiring harness for engine control module. DO NOT connect to engine control module itself, Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1598/31 Test Box" Testing and Inspection
- Test following wiring connections for open circuit and/or short to B+ or Ground (GND).

VAG 1598/31 Air conditioner, terminal
test box socket
41

Resistance in wiring: max. 1.5 ohm

- Correct any open/short circuit as necessary.
- If no malfunctions are identified in wiring, check function of climate control.
- Display readiness code, Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Displaying Readiness Code" Testing and Inspection . Readiness code must be generated if DTC memory was erased, Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Generating Readiness Code" Testing and Inspection
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