Replacing an air cooler fan can be a simple task that can be done by following these steps:

1. Unplug the air cooler from the power source.
2. Remove the screws or clips that are holding the fan grille in place.
3. Take off the fan grille and set it aside.
4. Disconnect the power cables or wires that are connecting the fan to the air cooler. You may need to use a screwdriver to loosen the screws or clips that hold the wires in place.
5. Remove the old fan from the air cooler by gently pulling it out.
6. Place the new fan in the same position where the old fan was located. Make sure the new fan's orientation is the same as the old fan.
7. Connect the power cables or wires to the new fan. Ensure that they are connected securely and correctly.
8. Place the fan grille back into place and secure it with the screws or clips that you removed earlier.
9. Plug the air cooler back into the power source and turn it on to check that the new fan is working correctly.

If you are unsure or uncomfortable with replacing the air cooler fan,it may be best to hire a professional from Locals4u for assistance.