Common Causes:Fear not! It may just be a very simple problem.

This problem can be cause by a couple of  possibilities (ranking from the most probable):

1) A faulty miniature aircon ON/OFF switch. Most probable (and cheap to repair)
2) A faulty aircon remote controller that keeps sending signal repeatedly.
3) A faulty aircon PCB (printed circuit board, the electronics board), indoor unit.
4) A faulty aircon PCB (printed circuit board, the electronics board), outdoor unit; if it is an Inverter system. (least 
probable and more expensive to repair)

A) A faulty miniature ON/OFF switch. Most probable (and cheap to repair)

 This is a picture of a miniature aircon switch found behind the cover of the ON/OFF switch button. If the switch is wet of faulty, it behaves like you had pressed the switch, thus turning ON/OFF by itself. The simplest thing and most economical way to do is to remove the faulty switch because most people do not use it at all.

B) A faulty aircon remote controller that keeps sending signal repeatedly.

If your aircon remote controller is faulty, it may keep sending out signals repeatedly even when you are not pressing the button. Bring it to another air conditioner that operates using the same remote controller (if there is any) to see if the problem migrates. If it does, discard the faulty remote controller and buy a new one.

C) A faulty aircon PCB (printed circuit board, the electronics board), indoor unit.

D) A faulty aircon PCB (printed circuit board, the electronics board), outdoor unit; if it is an Inverter system. (least probable but very expensive to repair)

This happens only if it is an Inverter air conditioner. An inverter air conditioner is a dynamic system whereby the indoor unit and outdoor unit communicates in a 2-way manner. Some models are equipped with a condenser “test run” function. Thus, if the outdoor PCB test run function is shorted, it can turn on the indoor system. As with “A” above, always check the miniature switch first (outdoor unit).