| Checking air conditioner compressor cut-out |
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| The air conditioner compressor signal informs the engine control unit that the compressor is to be switched on in 140 milliseconds. |
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| The engine control unit can send a signal via the same wire to shut off the air conditioner compressor. |
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| The engine control unit will shut off the air conditioner compressor in the following circumstances: |
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| In the case of powerful acceleration (full load in 1st gear) |
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| In emergency running mode (limp-home) |
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| After starting basic setting (function 04) |
Note | t
| No fault stored in engine control unit fault memory |
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| Vehicle at room temperature (above +15 °C). |
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| Connect up the vehicle diagnostic and service information system -VAS 5052- and select the engine electronics control unit. Engine must be idling. |
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| Select the function “Read measured value block”. |
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| Select “Display group number 050”. |
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| Switch off air conditioner. |
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| Specification for display zone 4: Compr.OFF |
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| Switch on the air conditioner with the “Auto” button and set the air conditioner to maximum cooling/heating output. The compressor must run. |
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| Specification for display zone 4: Compr. ON |
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| Floor and release the accelerator quickly (short blip). |
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| Specification for display zone 4: The display should change from “Compr.ON” to “Compr.OFF” for a few seconds (air conditioner compressor shut-off during acceleration). |
| If the display in zone 4 is not as described. |
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| Connect the test box -V.A.G 1598/31- to the wiring harness to the engine control unit, but do not connect the actual engine control unit → Chapter. |
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| Check for open circuit and short to earth or positive in the following wiring: |
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