Hi
If the car was overheating due a faulty radiator switch, it would make sense to bypass the radiator switch and connect the fan directly using the two wires which connect to the radiator switch but only as a temporary measure to get you home as ultimately you would burn out the fan motor if connected directly long term. I really do not understand why cables are being bypassed within the car. If your car was overheating due to a faulty radiator switch, you need to change the radiator switch. It is an easy job. Change when the engine is cold, top up the cooling system and then bleed the cooling system to eliminate air locks.
As mentioned there should be two cables going to the radiator switch but the fan may have been disconnected at the block connector. It might be worthwhile posting a pic of the radiator switch and the radiator fan wiring so that we can see if the wiring has been doctored and then advise as to how to put it back to its original configuration. Then it would be a case of re-diagnosing the original fault which convinced the expert of bypassing components in the first instance.