AC units are among the most expensive systems in a vehicle to replace or even repair. If your car's air conditioning unit is too far gone, it might not suffice to simply repair, replace, rebuild, or re-condition individual components of the AC system any longer. Instead, you might have to overhaul and replace the entire AC unit. At the very least, you're looking at a bare minimum of $1,000 to do this. Meanwhile, some cars have highly advanced AC systems that could cost you as much as $4,000 (or even higher) to replace. On average though, a brand new AC unit for your car will cost you somewhere around $2,000.