Going through this myself at the moment as the AC I have got a leak in the evaporator A frame inside and is the old R22 coolant system. First bid in is $6300 to replace the condenser compressor (outside unit) and heat exchanger A coil (inside unit) and flush and reuse the old coolant lines and install new R410 components. God all mighty. I "knew" a guy and I bought all this stuff for $1550 back in 2012 under his license and another $1400 in labor so less than 3k back then. Full MSRP on the stuff I bought would have been $4087 total, or 2.84 times what I paid at jobber. I know R22 is around $140 a pound, but this tough to accept. It's a 4 ton unit for a 1800 sq ft house with a 1800 basement.