My AC compressor runs continuously even with the control on it's lowest
setting. On or off, that's it, nothing in between. Once, when it was not
real hot, I think something froze up after a couple of hours - the fan
seemed to be blowing less air volume and not as cool - as if something were
partially blocked, and when I parked the van, a couple of hours later I had
what looked like a gallon of water on the pavement at the rear near the
tail pipe.

What are the potential causes of this problem, and how much is this going
to cost me?