2005 Nissan Sentra AC control panel

I was recently driving and I noticed the air/heat wasnt blowing from the vents. I began to change the ac panel and it seem broken but I over looked this initally. So as a worrier I thought it was my compressor or blower but then I took it to auto zone and they said the air is blowing but its only blowing on my feet which means the ac control panel is broken, so how do I repair this or should I go to the dealership/how much should it cost?