Review the operating manual if you are not familiar with the model of the electric fan.

Inspect for loose connections or broken wires.

Always suspect a faulty contact on mechanical switch circuit rather than defective electronic components. 

Do not use needle-pointed probes for better contact and to avoid short circuiting nearby components.

Ask for the detail about the problem and how long it has been happening.

Prepare the tools needed and remove the cover ready for inspection.

Wear cotton gloves while troubleshooting to avoid the electrical shock. Also note that, especially in tropical countries, sweat on hands may cause accident.

Try to determine the last time it has been modified/repaired prior to you.

Replace an opened fuse or burned resistor unless, you have corrected the

trouble or have detected.

Ask questions to the owner/operator of the electric fan to identify the problem to you.

If you have worked on it before, check it out to see if it still operates in the same way.

Review the service manual for the unit prior to any testing.

Discharge large capacitors by connecting a jumper wire across their two conducting terminals.

Do not apply careful physical inspection of the suspected parts/components.

Always be careful about the polarity of the components when replacing

them. Electrolytic capacitors used in transistors or integrated circuits have only low voltages.