My 146 1.8TS idles perfectly when the air-con isn't being used. As soon as I turn it on the idle starts to jump round a bit.
Its at its worst when I come to a stop and drop the clutch, the revs drop to the point of almost stalling and then rev up to 2-3k and back down and up and down until it settles in its lumpy state again.
Turn the air-con off once again and it behaves perfectly.
Is there anything anyone can think of that could be causing this? Is the air-con supposed to be connected to the ECU to let it know there will be more load on the engine or should the ECU react fast enough to increase the throttle so the revs don't drop too low. I don't get this problem when the radiator fan cuts in or I turn the lights on, etc. Only the air con.
I had something similar on mine, and supposedly it was caused by the 'Multi V Belt Tensioner' that runs the air-con aswel as some other bits in the car. Mine was idling funny aswel. One minute it would be at about 800, and then it would rev quite hard sitting there on about 2k-3k.
Is the engine making a funny slight knockin noise, as there was also a problem with the Multi V belt tensioner bearing on my car.
on my alfa 146 t.spark i had the same prob but stoped and i done this as the woman who had it before never used the car or any thing , i like to use the air con once a 2 weeks at least to keep things running nice tho i live in hot england lol , but after having so use it is fine , so give it some use.