I am using my ac system but i don´t see any water dripping under my car. 

I try to find the ac drain line but no luck.

Any help? where is this drain line located? 

 

You need to get the AC properly discharged by a garage. There's Schrader valves fitted so that you can use an refrigeration manifold to recharge the AC, but you shouldn't touch them unless you're qualified.

I don't see what the issue is though? You shouldn't have water dripping under your car.

I agree with Luke. There should be no water under your vehicle during and after AC usage. The only time I've seen an issue with an AC system dripping water was when the water pump in my 02 Astra was failing and the engine was getting too hot which caused condensation on the pipes. 

As Luke said, because of the gas used, any work on the AC system has to be done by an approved garage because it is hazardous to the environment if discharged. 

It's normal to have water dripping during AC use, but it's not a necessity.  The moisture in the intake air condenses on the cold evaporator in the car, when there's enough it obviously drips off and runs out through the drain.  The HVAC drain pipe isn't part of the system that only a qualified person can touch.

Saying that, if the AC is working and the water isn't stuck in the car (you'd smell it if it was!) then I'd just leave it tbh.

Don't have any problem with the water. The car was giving sometime a bad smell and I clean the ac vents and now is ok. I only see a video where it say that when the ac is working I should see water dripping under the car, if not that mean the drain pipe is clogged. Now I only wanted to check where it is and check if is clean.