Had this problem for about 6 months now.When the engine is picking up revs quickly i.e accelerating in 1st,2nd & 3rd gears the ancillary belt squeels.I've now changed the belt, tensioner,ace pump,alternator/vacuum pump,and power steering pump trying to fix the problem as well as using belt dressing but i'ts no better,havent changed the a/c compressor as it spins freely as does the cooling fan pulley.Cant hear which pulley is slipping as the noise is so loud,vacuum pump does get warm quickly but this is probabily normal(tried disconnecting vacuum pipes but no better).any suggestions?