The early cars came with a switch that had only 2 connections and switched both the compressor and the condenser fan on and off together. It was determined that the condenser fan should run for some time after the compressor was turned off to prevent a pressure rise in the system that could cause hose ruptures so a switch with 2 contacts was used, one contact to cycle the compressor based on temperature in the evaporator coil and a second contact to control the condenser fan. The second contact would be closed full time whenever the AC control switch was in the on position. There was a tech service bulletin issued by Ford to retrofit this switch to earlier cars but unfortunately those switches seem to no longer be manufactured.
SO Bill provided a diagram to add a delay to the condenser fan that will do essentially the same thing. Another way to provide the same protection is to use a trianary switch to control the condenser fan based solely on head pressure.