I just bought a 2008 Tahoe with 126k miles on it on Sunday. The rear A/C has a weird problem that I can't find the answer to after searching on the internet for the past 3 days. The rear controls are located where the drop down screen is location on some models. All three knobs are not lit, which tells me they aren't getting power. I've checked every fuse associated with the system and they're all fine. I'm able to control the rear air perfectly from the front controls as long as I'm in AUX Mode. However, when in AUX mode I cannot control the air from the back controls. Any ideas??