2003 Toyota Corolla Cracked Radiator

I took my car to the mechanic today to have my AC serviced. My AC just intermittedly blows hot air. Not for long and not often, but I wanted it looked at. They said my AC needed services (I thought this would be true). They also said my radiator was cracked and that also caused this. When I spoke to my father about that he said if my radiator was cracked I would see leaking. I have not seen any leaking.

So, is the mechanic correct or just trying to get more money out of me? Should I have him replace the radiator?