Why would a 2000 Dodge Neon AC quit working suddenly with no warning?

The same has happened with my 2000 Dodge Neon. Mine is a manual transmission 4 Door Sedan. A month ago my a/c stopped working and started blowing hot air. Strangely, if I move from vent to defrost and then back again the a/c sometimes comes back (mildly) for up to 15 minutes. It also seems to be effected by my accelerating, more acceleration more cool air for a little while. It always returns back to hot air, though. I had a mechanic check the fuses and the gas level (freon?) and they were fine. The mechanic theorized that the clutch compressor is broken. I called my dealership and they said they could test my A/C system for $135.00. When I said it might be the clutch compressor they offered to transfer me to their parts department. It is my understanding that if it is the clutch compressor it will cost 300-400 dollars. The sad thing is that this car only has 26k miles on it. Grrr, I say. PLEASE try a freon recharge first. I got that "failed compressor" theory from a mechanic, too. Mine was a hose that was leaking at the seam. Yours sounds like it needs a recharge. Get a kit from the auto parts store (about $15-20) and do it yourself-see what happens. Did anyone check the tension on the belt? If these are the original belts its possible the belt is getting loose or breaking down (more due to age rather than use).

The defrost setting also turns the compressor on in order to remove humidity from the air stream. By switching to defrost and back you are temporarily cooling the expansion coil. This would indicate that the compressor and clutch are working correctly. I would expect a bad dash panel switch.