There are many questions about air conditioner issues with the most common being that it isn't cooling properly. Among the typical answers are low Freon and the standard diagnosis for low Freon is ice on the large copper pipe at the outside compressor.
From my understanding the small copper tube is the high pressure side with Freon that has been compressed to a liquid. When this liquid is allowed to boil in the inside evaporator things cool down.
Conversely the large copper pipe is the return line from the evaporator sometimes referred to as the suction line or low pressure side.
So my question is: under low Freon conditions how can the suction line freeze up?
Intuitively I would thing with low Freon the entire cooling ability would be below normal causing the evaporator to not produce as much cold air. A side effect of all this, I would expect the suction line to be warmer that normal.
Why does the suction line freeze up under low Freon conditions?
See the image in this question for a great diagram of an HVAC system: What's the most common cause of A/C refrigerant lines freezing?