A/C blows cold, then stops, then starts again.

What is your question?

We have a 1992 Caravan with lots of wheelchair modifications for our son. The A/C will blow ice cold for 5 - 10 minutes, then it sounds as if something flaps closed and no air of any kind. It sounds as if the system is still blowing but no air comes from the vents. If we shut if off for 5 minutes or so it'll come back on. My son is paralyzed so we dearly need to keep the old clunker going -- there isn't money for another. The last time I took a car in for A/C repair I got taken and want to be prepared when bringing it in, if possible. Thanks in advance for any suggestions.