Smelly Air Cond System
 

I've been driving my mazda 3 (Sp23) for more than 2 years now, so far so good.
Lately, the air cond becomes very stink due to damp and some moulds or bacteria.
I sprayed with the disinfectant (Pino Cleen Glen 20) and turn the air cond. on and let it circulates for 30min.
The smell gone but it was off temporarily only. The next day, the damp smell came back again..It's so annoying.
I have also tried with regulate the air from the outside to dry the air cond system but it did not help much.

Is there a better way to tackle this problem?