I just noticed that my hvac switch is not functioning, meaning that turning it to different modes does not do anything. AC and fan still functions, just that it doesn't go into another mode such as defrost, etc. It just blows out of the dash top vents. Could this be as simple as a blown fuse, or could it be wiring or motors? Anybody have any ideas?

 

There is a thing called a "mode control motor". It's hidden deep in the bowels of the HVAC box inside the dash. It is possible that this motor is not working. Why it's not working could be a few things. The motor itself may be gonzo. The wiring harness may have come loose or detached or the fuse for it has blown.
Start with checking all the fuses first as this is something you can do yourself. The other things will be tough. Getting at this motor will not be a "cake walk".