In the last few weeks a fairly significant whining noise has started emanating from the front of the car. Going on a couple of old threads, I'm suspecting airconditioning compressor. Whine stops when the a/c is turned off; and sounds like a small jet turbine starting about 10-15s after the engine is started (a/c is on auto). The volume of the whine varies with engine revs, being at its peak at around 1800rpm, give or take.
Is there anything else linked to the a/c which could also whine? And if a/c compressor, does this mean eventual failure? a/c seems to be working as normal (for some definition of working/normal

).
philip