One problem related to air conditioner has been reported for the 2009 Toyota Prius. The most recently reported issues are listed below.
A year ago, upon taking off from a stop my car began to stall. I drive two blocks it continues to putt along and stall, then after less than a mile it starts to run as normal. I take my car in to be told it is out of gas, which it did not indicate low fuel, it had over a quarter of a tank. I insist they continue to check my car over days of them driving it, after a week they experience something similar and replace my junction box. Since then I've replace the water pump, taken my car in for a steering recall. Also, there are instances where my car upon take off stalls, but nothing severe, just something you feel when accelerating. Recently, 6/5/14, I experienced the same issue, but this time I immediately put gas into my car even though my indicator panel shows I have fuel. Only this time I start my car and the air conditioner is not working and it continues to stall, after turning my car on and off several times and driving a few blocks the ac cuts on and my car begins to run fine. I have been told by Toyota that bc there is no indicator light and it's running fine there is nothing they can do. There was a recent recall in February of 2014 with similar issues I am experiencing but my car was not apart of the recall. Not sure what else I can do. Numerous Toyota dealerships have been of no help and I fear that my safety is at risk.