E9A Checking Idling-Speed Increase on Cut-In of AC Comp.

E9A Checking the idling-speed increase on cut-in of AC compressor (cars with auxiliary air valve)

Tools:
- Multimeter
- Tachometer

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

2 Press the AC button. Engine speed should then drop noticeably and then return to normal idling speed again.

3 It it does not:

- Check whether voltage is present at the AC compressor's single-pole connector at the compressor (red; RD).

- Check the AC unit's electrical system (power supply to the electromagnetic clutch).

- Check whether voltage is present at the IAC valve and whether it opens.

- Check whether voltage is present at the AC unit's 11 5°C (240°F) thermostat (see section 854, Service Manual 8:3).

- Also check that the yellow (GL) lead between the IAC valve and the AC unit's 115°C (240°F) thermostat and the black (SV) lead to the alternator grounding point are OK.