Mechanic Changed Tension Bolt - Now A/C doesn't work?

I brought my car (2010 Ford Focus SES - 80,000 mostly highway miles on it) to a local small business mechanic who is very reliable in my small town. I have never had any trouble with them before and their prices are always reasonable.

However, I had a problem with the car accelerating and making noise and they discovered that I had a defective tension bolt. So they replaced the tension bolt, the tension belt, changed a tire, and fixed my oil. They did a great job with everything… Except…

My A/C did not work. The air blows through the car but it's hot. So I called them and they said that they must have "knocked a line loose." So I brought it back and within 5 minutes, they had me out the door and on the road. My A/C worked but it was warmer than usual. However, I thought that I was just being irrational because it was 95 degrees outside and I thought that may have been why.

Didn't drive my car again until just now. It's cooler outside and not only does my A/C not work, it's making a weird noise like air leaking from a container. It's a weird sound and only happens when I turn my A/C on. When I turn it off, the sound goes away.

Does anybody know what may have caused this? My A/C was fine before I brought it to this mechanic.

If they "knocked" a line loose, that means all the refrigerant out of the system. There's no way they fixed it if they sent you right out the door. To properly fix AC systems, after a repair is made, you have to hold suction on it for at least 30 minutes, and then check for leaks, if its good you have to recharge it which takes about 5-10 minutes, then fine tune it by adding or removing more refrigerant. It sounds like they did knock a line loose and just hooked it back up, but if your hearing the whistling noise your ac system is leaking. Your mechanic screwed you over badly. Don't listen to Chelsea Collins, the belt will either be on the pulley, or not on it at all. And it doesn't matter which way it spins. Its a piston pump, if it spins it moves the piston.

If it's not blowing cold at all double check he put the belt on right, he could have put the belt on wrong. He could've put the belt over the compressor pulley, not under it.