Cabriolet V6-2.8L (AFC) (1995)
A/C Compressor Signal: Testing and Inspection
A/C Compressor ON Signal
CHECKING A/C COMPRESSOR ON SIGNAL
The A/C compressor ON signal increases the basic value forthe Idle Air Control (IAC) valve, ensuring that idle speed remains in the center of the
control map range.
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Using VAG 1551 scan tool, initiate "Read Measuring Value Block" function 08, display group 004. Refer to On-Board Diagnostics under
Computers and Control Systems. See: Testing and Inspection
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Display will appear as shown:
Read Measuring Block Value 4
1 2 3 4
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Observe first digit of 4-digit display (switch inputs) in display field 4.
^
Specified value: OXX X
NOTE:
Switch inputs shown by digits 2 to 4 are ignored for this test.
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Switch A/C on (manual A/C) or, with automatic A/C, press buttons "AUTO", temperature "LO" and blower speed "HI."
^
Specified value: 1XX X (zero changes to one)
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Press "arrrow" button.
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Press buttons -0- and -6-to select "End Output" function 06.
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Press -Q- button to confirm input.
If the 4-digit display does not change:
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Switch ignition OFF.
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Connect VAG 1598 test box with 1598/11 adapter harness to ECM and wiring harness. See: Testing and Inspection/Scan Tool Testing and
Procedures/Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1598/31 Test Box
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Connect LED tester to test box sockets 11 and 45 (Ground).
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Switch ignition ON.
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Switch A/C on as described above.
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LED must light up
If the LED does not light up:
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Disconnect ECM harness connector C.
If LED now lights up:
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Replace ECM .
If LED does not light up:
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Check continuity of wiring and/or short circuit using wiring diagram as follows:
For manual A/C:
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Check wiring harness between ECM connector C terminal 11 and A/C switch -E30-.
For automatic A/C:
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Check wiring harness between ECM connector C terminal 11 andA/C control head -E87-.
If wiring harness is OK:
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Check A/C system.