My rear A/C unit was blocked off before I bought the vehicle how do I fix it?

Hello, The best guess I can provide without looking at the vehicle is that the rear evaporator core or orifice tube was defective, or there may have been physical damage to the lines under the rear wheel-well. This sounds like a workaround, and I have never encountered it. It might even be that deleting the rear A/C was an option from the factory, but if there are rear A/C controls, I would not expect that to be the case.