Please clarify whether the issue is that the air is not cold or whether you are not receiving enough airflow from vents.
First, please also check cabin air filter first
Second, check that when u turn on A/C the 2 fans near radiator turn on.
If it has to do with cooling then you should check your condenser which is located in front of radiator, if its dirty give it a wash with a hose with low pressure.
Otherwise it could be that your evaporator coil which is inside the car is dirty.
If its none of these then maybe it has to do with compressor.
Which city r u in so i can recommend mechanic?