can I drill hole in ac drain line and unclog it from inside passenger floor?

What is your question?

i was told i could drill a hole under dash in the spot where the drain line for ac goes threw the firewall and unclog the drain line..i tried a cloths hanger and it wont go but about 3 inches into tube from outside and didn't work so my question is can i drill the hole and unclog it from the inside of the cab under the dash?