See if you have a two wire connector on the outside of your evaperator caase under the dash, this will be the evaperator fin temperature probe, it is a veriable resistor that monitors fin temperature by changing its resistance as it gets colder, it has a negative coefficient meaning that as the temperature gets lower the resistance gets higher. I think your resistance is not getting high enough and the compressor is staying on too long allowing the water condensation that builds up on the evaperator to freeze. Normally the AC Amplifier will monitor this resistance and cycle the compressor automatically to keep the evaperator from freezing up and killing air flow. Do you have the air switch to recirculate or fresh air, it probably does not matter in your case but one will bring in more fresh humid air while the other will continue to dry the internal air again and again and act as a dehumidifier within the car. Just for diagnosis yuo can go to your local Radio Shack and see if they want to learn something new, get the car cold, quickly turn off power and disconnect the two wire plug and measure the resistance of the fin probe (use this as a base line reference, you will need more resistance than this to kill the compressor) and substitute a variable resistor (potentiometer) in the cars harness and see if you can get the compressor to turn off manually at a certain setting. This could be a permanent fix or last until you are forced to go into the evaperator case for additional repairs. The store sales people will know what I just said so print this out and give it to them. I drive a 1995 Odyssey and my fin probe will only allow my temps down to 14C. Most cars go down to 6C in my area this time of year.
Duane in Japan
Tachikawa Shi, Tokyo