heater not working

[Pickles]

So, my heater fan stopped working. What happened was I started the car one day with it set to 3. Was working fine. Turn it down to 2 completely shuts off. Also rear defrost and air circulatory light turn off. Go to work and worry about it, then I leave ans it is fine. Wtf. It is now 3 days later, and it quit again. When the fan is set to off the defrost and air circulation light on the buttons works. When I turn the fan on, the lights dim and it doesn't turn on, and the button lights shut off. I checked every fuse and relay, and all the wires going to the controls. Is this something a warranty repair? I think my car is still under warranty. Or is it a simple fix I can do at home? Any help would be great, it's freaking cold out

Edit: when I say the lights dim, I mean the dome lights, the lights on the buttons shut off completely