I just had my air conditioners cleaned by a professional and I asked him what I could do to help prevent mold and this was his advice.
Before you turn off your air conditioner, run the fan mode for about 1 hour. The reason why you get mold is because using the AC results in a lot of moisture on the fan blades. You need to dry the fan blades before you turn the air conditioning off. On your air conditioner remote control, this button is the 送風 button. This should help prevent mold buildup. He mentioned that If you follow this advice, you only need to clean your AC every other year.
by nidontknow