The thing under glove compartment is basically an "Evaporator", and yes in order to have a better "thandi hawa" from your AC, evaporator should also be cleaned with pressure water. and dont worry the water will not fall into cabin, if you look closely there is a v small pipe going from under that evaporator box to outside the car, that basically throws out a condensed water outside the car when AC is running (this is why you see water drops under the car when you are using AC). and you cannot clean it with a wet cloth, since its just like radiator grill.
You just need to
-remove glove compartment by pulling its clips.
-remove the small circuit board type thing which is mounted in front of evaporator box.
-open a screw of evaporator box (screw head facing downwards) and a metal clamp
-turn duct to "outside air" or "fresh air" side (this further ensures water to not enter into cabin)
even then you wont be able to look evaporator clearly, but you will have an opening to throw pressure water in it for washing. Better you should have a thin metal type pipe (which AC walas have normally) so you can direct water through that small opening).
water will be drained out through the pipe I mentioned above. I havent done it myself. But once I got my AC service and this was the procedure.
I can share pics if you are still unable to understand.
if still you are not sure, then just put a small amount of water into evaporator box and observe....
Yar I dont think that there is an AC blower filter in cuore. Its evaporator.
He is "killing" bongiaan. (bongiann maar raha hai :)) No need to remove the carpet at all. the method I have described above.