My 1.8 Connie used to growl when the aircon was switched on. After a regas it was fine. Quiet and efficient. My aircon man tells me that they all lose a percentage each year, so I get my latest car done every two years. The refrigerant has something in it which refreshes the seals. I have had one seal that needed replacing (bottom hose connection) but that is all. Car was an 05 with 80k on it.