My 2000 TL has been flawless up until now. The air fan seems to hiss particularly loud, especially from the right side vents. Also the AC does not seem to be cold anymore. I actually think the AC isn't working at all as warm air comes out of the vents. The problem just suddenly happened. Does anyone know what the problem may be? I hope it's not expensive to fix.

 

First check the cabin air filters located behind the glovebox $20 USD fix and 20 minutes DIY
then check the freon level in the AC system