BMW Repair: A/C icing problem, shop mechanic, code scanner

Question
Hi there,
I have a 2001 318i. The A/C works fine but after an hour orso of traveling, the the air flow from the louvre begins to reduce as if being choked up by something (ice?). I'd have to turn off the compressor for a few minutes to get everything working again - only to repeat the whole cycle again. The problem is more acute in cooler weather condition!. When i stop my car, i 'd see a huge pool of water under the car, with ice chunks on the floor!
When i raise the A/C temp setting, I don't feel any change in the cabin temperature.
The w/shop mechanic did not find any fault with the code scanner.
Please throw some light on this problem

Answer
Hi Ku Wah!
The basic problem is that there is not enough air blowing into
the fins of the  cooling coils of the evaporator, so ice forms. First check the microfilter if it is clogged with debris, which I doubt. If it is reasonably clean,and the blower fan works,
there is a service bulletin for this (note that this is not a recall) which says what to do. The bad part is that you have to pay for it to be corrected. You should bring it to a dealer for re-programming/coding of the IHKA (AC control module).
Happy Thanksgiving!
Tino