No air from vents?

My A/C &Heater unit just stopped blowing air all of a sudden. The unit still blows air but not when I turn the level from low to high, it just stays the same. What could it be? It was hard to see if there was a leak due to the bad weather, but before the A/C Heat unit would not adjust to the level I turned the knob to, but have a realy long delay in adjusting the level. For example if I turned the knob all the way up and then turn it all the way down, the air would still blow at the high level for and extra min or so and then finally go down to the correct level. I was told that it could be the head unit/air con panel switch with fan switch (something like that).

The unit still heats up and still blows cool air.

What would be a possible cost of repairs in the situation of the control panel or the blower motor repair?

Before I was having problems with the unit where it wouldnt heat up unless the accelerartor was pressed or car was moving, but after adding coolant which was needed that problem no longer exists, I was wondering if these issues could be related also.