Q: AC stops blowing cold air

I have seen this before. It is not a very common issue but it does happen. Behind your dashboard there is a radiator like part that circulates refrigerant into your vehicle. The air blows through this radiator like part called an evaporator. This is the air you feel in your vents. On a rare occasion the evaporator gets a restriction of some sort, this restriction causes the refrigerant to slow down even more and freezes the evaporator. Since it is now a block of ice, air will not flow through it like before and it stops blowing cold air out of your vents. Once the vehicle is turned off, the part unfreezes and it works great again until it freezes. The common repair is to replace it along with some other components like the expansion block and dryer. This can be a complicated job that may require dashboard removal on some vehicles. I recommend having a certified mechanic come and inspect your vehicle’s AC system to see what repairs should be made.