Using the dedicated detergent for washing air conditioning (for example "Dichen" that is used when there's too much greasy dirt in the air conditioning that the refrigeration is affected. The effect is pretty good.) Such dedicated detergent is sold in refrigeration parts store.
Heating the film with electric hair drier and then clean it. The effect may be better.
If the surface of the household appliance is metal, you can use fire to burn it away.
I suggest you not to use fire to burn it. You an use a piece of rough cloth or the cloth we use to do the dishes. If you are afraid to scratch the surface, you can slowly wipe it with some toothpaste. If wipe it using steel bush with water, the color of the metal surface may change.
