Making the world better, one answer at a time. The cost of an AC compressor depends on the size of the unit, where you live, and who is going to install it. In general, a 2.5 ton compressor will cost between $1000 and $1800 depending on the manufacturer and installer.One user said: You can find a 5 ton compressor for under $1000 online.aking the world better, one answer at a time. The cost of an AC compressor depends on the size of the unit, where you live, and who is going to install it. In general, a 2.5 ton compressor will cost between $1000 and $1800 depending on the manufacturer and installer.