My first job as a paid employee of the family auto shop was as a member of an installation team of add-on under dash air conditioners. We had a distributorship for Mark IV and later Climatic Air add-ons back in the late 1950's and early 1960's when most vehicles were sold without factory air conditioning. One man would install the under-dash evaporator, cut holes in the firewall for the hoses, and do anything else needed in the passenger compartment. The other guy would install the "adapter kit" under the hood- - - - -condenser, compressor mount, extra fan belt pulley sheaves and idlers, etc. With everything installed, the system would get a vacuum pump applied for 2-3 hours, Freon was added, and we'd drive an air conditioned car to lunch. We'd install another one in the afternoon. Parts and labor for one of those jobs was around $300.00 or so, a healthy sum when minimum wage was around $1.00 an hour! That was also approximately the cost of an "out of frame" engine overhaul including regrinding the crankshaft, grinding the valves, boring the block and installing new pistons at the time!
Jerry
