Check if the Evaporator filters are clogged. Maybe the Evaporators itself are clogged.
Check also the function of the blower. If the blower is weak, it will not be able to let enough air pass through the evaporator...hence the evaporator's temperature will drop until it reaches the freezing point.
I experienced this before in my old old tsikot..what I normally do is I just turn the A/C off...let the blower run...the ice will melt in a few minutes..then turn the A/C on again. This is only a quick fix until you are able to find time to properly clean your system.
