The electric condenser fan does not come on when the A/C is turned on? The compressor kicks on when the A/C is turned on like it should. This is the RAM with a shift driven fan with fan clutch and the electric condenser fan. It is a Ram 1500 Big Horn with a 5.7L engine.
Typically there is a fuse and relay in the electric fan circuit. Ultimately you could use a power probe and supply the electric fan motor with juice and see if it works. If it does you know you are not getting power supplied to the fan motor. This would be either a blown fuse or failed/sticking relay most likely. Other than those components you are left with wiring and connections. Use the wiring diagram to help assist you in diagnosing the exact cause.