What is the difference between the amount of electricity(cost)to run a fan and a small air conditioner?
Good question. A fan is typically just an electric motor with a fan blade attached to the shaft whereas the air conditioner requires a motor to operate the compressor, pump and blower assembly.
Most household fans consume less than 50 watts. A large ceiling type fan might run 75 watts.
A window mounted air conditioner rated at BTU or heat capacity. The power consumption varies because the compressor motor combination is constantly switching off and on in order to keep the refrigerant cycling properly to cool the room and not freeze up the vents. Here is a good article to read:
The power for a small single room air conditioner might run 1500 watts when it is operating full time.
The electricity consumption is much higher than a fan; could be 5 to 10 times greater, depending on the specific units and the temperature of the air in the room.
Let me know if you have more specific questions.
Have a wonderful day.