2001 Chrysler Town and Country two burned up AC compressors

I have an 01 town & country with a problem with the ac compressor. When I got the car, the compressor wasn't mounted securely to the engine, and the compressor clutch was burned up. (Melted rubber coming out of clutch.) A new compressor was installed and drier, and the line blown out. It worked great for approximately 3 months and I could hear the compressor cycle on and off occasionally, which seemed normal. Then I took a trip of over 150 miles, and the ac compressor seemed to lock on and would not shut off, even when I shut off the ac. Incidentally, this did happen in the summer, so we were using the ac. On the return trip home, I only got about 60 miles and the clutch burned up in the ac compressor. It was smoking and burning. It would not even shut off when I shut off the power to the climate control system (in the town & country, you can shut off the climate control with the power on button). To shut off the compressor, I had to get under the car and cut the wires to the compressor (which I assume controls the clutch). After that, it remained off and did not burn anymore. Any insight you can give me into this problem would be most appreciated.