I'm new here, forgive me if I'm not allowed to post about a GMC on a Chevy forum. Also, I'm sure this topic has come up before, I just can't seem to find the answer.

Long story short, I have an 02 Yukon XL 1500. Front HVAC seems to work fine, but the rear HVAC doesn't seem to respond to the inputs on the rear controls at all. I recently purchased these vehicle, so I don't know much about its history. Where should I start looking for the culprit?

Thanks!