My aircon is freezing up, can I fix it or can I own it fixed.? After running the airconditioner for more than 12hours it builds up with...

After running the airconditioner for more than 12hours it builds up with rime behind the filter and today it started making a loud rattle hum, can it be fixed or is it due to go on the bit heap. I am hoping it is something simple because it is Christmas and up contained by north qld it is almost a necessity to get through summer.
Humidity Level?
Answers:    A/Cs freeze up for one of three reason
The coil that cools the air is dirty or filter plugged.

The fan inside or outside are not turning fast satisfactory

the system is low on refrigerant
Is it OK to put multiple (2 -3)...
Turn the power off to the part, and use a hair dryer set to a dignified setting. If it continues to ice up, you will have need of to get it checked. You could own a freon leak.