I have a 2008 Focus and the AC suddenly quit working. This was a cheap car I picked up and I knew it was in a front end collision. The radiator and AC condenser therefore was replaced. It had no refrigerant in it when I bought it. In April, I vacuumed the system, put in the oil and refrigerant. The AC worked fine until this week. It was blowing ice cold and suddenly it stopped for a little while and then started working fine for a while. It stopped again and started back up, but this time there was a bang and it felt as if the car was going to stall when the compressor kicked on. Now the clutch doesn't engage at all. I can see the clutch is not spinning when the AC is on. Does this mean the AC clutch is bad? Is it possible it could be low on refrigerant?