Wash Only or Chemical Clean

I bought a dehumidifier 2 years ago. Although I am not sure could it really reduces the level of humidity in the air or not, but I never stop to switch on it every night in my children bedroom. I already used it for two years; I wonder should I hire someone to clean it now. We could just open the cover and wash the filter only? On the other hand, really need a professional person to chemical clean dehumidifier like the air conditioning unit?