l just bought a 2007 scion tc from a repo sale the lights on the a/c / heater control does not light up at night. l have checked all the fuses they are all good every other light inside the car lights up and everything inside works. the a/c and heater both work but no back lighting so if l wanna adjust the air or heat l have to turn on the inside light . so is there a main bulb that is out behind the a/c heater control? How do l get behind the unit to change the bulb?

l had the EXACT same problem with my 2007 Scion tC that l bought brand new. Thats part of the reason l loathed my tC; the poor build quality. Take your car to a Toyota/Scion dealership and it will be fixed under warranty. They had to replace my entire HVAC unit.

UPDATE:
Let me guess, all of your other interior lights work with the exception of your HVAC lights?