AC Water leak inside the car

I have a 2005 Tucson. I found a lot of water leaks onto the driver’s side. I removed the carpet and I figured out that the leak is probably from the drain hose under the dash but after I checked the tube which releases water out of the car I found it’s Ok and has no clog. And after I took the car to the repair shop, he said the leak is from plastic box in which is directly connected to the drain hose. “The tube” he said maybe is full of water or the box is cracked and needs silicon or cold welding. But I don’t feel that he really could see the cracked area because the box is in a very narrow place as you now, and I am afraid that removing the whole dashboard is needed to fix the problem. I really don’t want to remove it, so I need your advice on how to fix it without removing the whole dash. And does silicone really work? And does cold welding work for such cases. Thank you so much.