Every year I bring my car (now almost 3 years old) to the garage for a check up. When I bring it the people from the garage usually ask if I also want the extra air conditioner check and servicing. Until now I've declined, because the car was rather new and I didn't think it was necessary to spent 130 euros on something that should work anyways. But now the car's warranty period has elapsed.
My question is, is it really necessary to get your air conditioner checked and serviced every year (on a car of 3 years or older)? If not, any recommendations on how often this is needed?