Hi all. I have a 2006 mk5 golf sport tdi with climate control. Aircon not cooling. Had it pressure tested (thought it my need regas) and ok but failed due to pump not switching in. Any ideas why?. Can't find a fuse or relay for it. Maybe pumps gone? Pump is 1K0 820 803 S. Anyone know the difference beTween S and other suffixes? Are they interchangeable? Is an easy home fit? Hope someone can help as it's a great car but dealer prices too high for value of car.