Correct E34 520i 24v M50 idle speed rpm

[ktteoh]

i'm from malaysia.

what is the correct idle speed for this model (manual transmission) ?

1. 600 rpm (without air-cond ON)
2. 900 rpm (with air-cond ON)

i see some snapshots on eBAY that idle speed should be 600 rpm without air-cond ?

[ktteoh]

a few related questions:

1. what is the correct procedure to adjust the idle speed ?
2. how to ensure a steady idle speed - any components/parts
that we need to clean etc ?