Air Conditioning - Air Conditioner not draining

I have a window unit that 's about 3 years old. It has started not draining out with the condensed liquid. Instead it runs back down in to the outside wall and through to the carpet inside. I've check the drain holes and run a wire through them to make sure they're not clogged. I can see the water accumulating in the pan, but it doesn't drain out. It hasn't been shifted or moved since installation, so I don't see how it would have become "tipped" toward the wall. Any ideas would be VERY appreciated!
Ursa

I would double check it to make sure it's tiped to the outside. some time someone may of bumped into the unit or kids messing around..

also check the hole that lets the water go from the part that is inside the house to the outside drain pan where the drain holes are... it will clog and can be hard to locate ,,, there may be a channel that you can see ,if you look at the bottom of the unit, it may require that the unit be removed from the window, and the cover taken off so it can be cleared ............dddon