Hi all, have a 2004 A4 S-Line. I am sure the air con needs regassing as when i put it on low its not very cold, colder than ambient but not as cold as i expect. However if i press the centre fan button it goes colder? is this normal? Also after using the aircon or having it on econ, when i turn the car off it makes a loudish whirring noise like a jet plane engine shutting down, it this normal? Cheers in advance.