V50 ac
 

Volvo v50Ac works when you tap on it why do I need to hit iï

If you mean "tap on it" as in tapping the ac clutch - the clutch gap is too large due to wear. You need to re-gap the clutch by removing the outer plate and removing shims.

+1. another sign of an overly large clutch gap is if the AC runs for say 15 minutes on a hot day and then just cuts out only to return after the car's cooled off.