A/C Compressor Cut-Out Signal

CHECKING A/C COMPRESSOR CUT-OUT.
During acceleration from a stop and from low speed, the A/C compressor is switched off for approx. 12 seconds. If the accelerator pedal is released sooner, the time decreases to a minimum of 3 seconds.

TEST CONDITIONS
^ A/C function OK
^ No codes stored in DTC memory
^ Vehicle at room temperature, i.e. warmer than 15°C (59°F)

TEST PROCEDURES
- Start engine and let idle.
- Switch A/C on (manual A/C) or, with automatic A/C, press buttons "AUTO", temperature "LO" and blower speed "HI."
^ Compressor symbol must light up
^ A/C compressor must run

- Using VAG 1551 scan tool, initiate "Basic Setting" function 04, display group 000. Refer to On-Board Diagnostics under Computers and Control Systems. Testing and Inspection
^ A/C compressor must stop (check visually)

If A/C compressor does stop:
- Switch A/C off, let engine continue to idle.
- Using VAG 1551 scan tool, initiate "Read Measuring Value Block" function 08, display group 004.

- Display will appear as shown:

Read Measuring Block Value 4
1 2 3 4

- Observe the second digit of 4-digit display (switch inputs) in display field 4.
^ Specified value: X0X X

NOTE:
The switch inputs indicated by digits 1, 3 and 4 are ignored for this test.

- Switch A/C on (manual A/C) or, with automatic A/C, press buttons "AUTO", temperature "LO" and blower speed "HI."
^ Specified value: X1X X (zero changes to one)
- Press "arrow" button.

If specified values are obtained:

- Press -0- and -6- buttons to select "End Output" function 06.
- Press -Q- button to confirm input.

If the display does not change A/C settings may be incorrect, proceed as follows:

- Check continuity of wiring and/or short circuit using wiring diagram as follows:

For manual A/C:
- Check wiring between ECM connector C terminal 10 and A/C clutch control module -J153-.

For automatic A/C:
- Check wiring between ECM connector C terminal 10 and A/C control head -E87-.

If no malfunctions are found in wiring:
- Check A/C system.

If "X1X X" is displayed:
- Briefly push accelerator pedal to wide open throttle position.
^ Display must briefly change to XOX X and, after releasing accelerator pedal, change back to X1X X.

If the values change as described:
- Check whether compressor is switched off when depressing accelerator pedal suddenly (visual inspection).

If the compressor is not switched off:
- Check A/C system.

If the values do not change as described:
- Replace ECM.