R. Kannan wrote:
I had a guy look at it. He says the there is low freon in the system
and so the heat exchange are is 'icing up' and not allowing bair
blown by the blower fan to get through. I would imagine that if the
freon level is low, it will not cool down at all. Why would it 'ice
up'?

Please don't top post.

When the refrigerant charge is low the evaporator coil is starved for
refrigerant. This results in reduced pressure at the inlet piston or
expansion valve, thus allowing the refrigerant to vaporize at a lower
temperature - below 32 degrees. At this point the first part of the
coil will freeze. Then, since ice is a fairly good insulator the
refrigerant will now travel further through the coil before encountering
an exposed surface. More ice forms and the process continues. Gradually
most or all of the evaporator coil will be covered with ice. This of
course blocks air flow through the coil.