Chevrolet Repair: 1994 chev g30 motor home van 350 v8, temperature switch, speed fan

Question
the ac works well, but will ice up with little air flow after a while on low speed fan, but will return to normal after a stop or turning it off for awhile

Answer
I'm assuming this is happening in the MAX position. After vehicle reaches a comfortable temperature switch mode setting to NORM. This will draw air from the outside to be cooled rather than from the inside on the MAX position.
That should correct the freeze up problem.