I really will appreciate some pointers to this problem. When the engine is on idle, there is this rattling noise which goes off either if I am driving or the ac is switched on. Have telephoned Audi dealers and earliest appt is in mid June. Visited 4 local garages and advice ranges from oil and filter change, changing the tension belts, bringing down the engine to locate the noise(booh!), to replacing the ac compressor. Any one ever experienced this? Any pointer will be greatly appreciated.