Why wont the back air blow cold in your 99 gmc Yukon?

If the back air in your 1999 GMC Yukon isn't blowing cold, it could be due to several issues. Common reasons include low refrigerant levels, a malfunctioning AC compressor, or a blocked or damaged evaporator. Additionally, problems with the climate control system or a faulty blend door actuator could prevent cold air from reaching the rear vents. It's advisable to have the AC system inspected by a professional to diagnose and fix the issue.