My air conditioning in one car hasn't worked since late last summer. We would've fixed it then, but the weather's generally not too bad where I live, so we let it go to save some cash. As summer approaches again, I think it's finally time to address this. Before I go to a service center, I'm curious as to what I might be dealing with. What are some main causes of A/C failure? The vents work fine, so we've just used the outside air while we can. This is obviously becoming more and more uncomfortable as summer approaches.