If you're experiencing issues with your 2012 GMC Acadia not blowing cold air, there can be several possible underlying causes. It could be a problem with the compressor or condenser that is preventing the air from getting cold. The refrigerant level in the system may also need to be checked as low levels can cause warm air coming through the vents. It's also possible that your vehicle has a leak somewhere in its system which will require repair before it can blow cold air again. If these don't seem to resolve the issue then you may want to take it into a mechanics shop for further diagnosis and service.