I have a 1991 Accord and back in May I had freon put in because it wasn't cooling very well. They also replaced a hose that was leaking. I have had no problems until today. I'm out running errands and I have the A/C on. I am on my last errand and when I get back in the car and turn the A/C on again it's blowing nothing but hot air. This just happened all of a sudden - one minute it's fine and the next I just have hot air. Anyone know what might be wrong or a way that I can find out what's wrong without getting a $300 bill from the shop? Thanks in advance.