E9B Checking Idling-Speed Increase on Cut-In of AC Comp

E9B Checking the idling-speed increase on cut-in of AC compressor (cars with IAC idle air control valve)

1 Connect the tachometer and exhaust extraction equipment. Start the engine and warm it up.

2 Press the AC button. There should not be any noticeable change in engine speed.

3 If engine speed drops noticeably, check the following:

- The current supply to pin 16 (red/white; RD/VT) on the LH control module.

- If no current is present, check the red/white (RD/VT) lead from pin 16 of the LH control module to pin 16 of the AC relay. Also check the operation of the relay.

- If current is present, check the yellow/red (GL/RD) lead between pin 3 of the IAC valve and pin 23 of the control unit connector, and the blue/white (BL/VT) lead between pin 9 of the IAC valve connector and pin 10 of the control module connector.

- Check the IAC valve as described in point I3.

- If the IAC valve is OK, try a new control module.