I thought I'd treat the inside of my WJ to a bit of a carpet clean (dont think i've ever done it in 9 years of owning it

) and lo and behold I found the drivers side front carpet is soaked...which might explain the bad condensation I get.
Doing a quick google shows that the AC drain plug can become blocked with nasty gunk and the water can back up, but videos and pictures really dont show where it is. Does anyone know specifically where the drain is and best way to clear it?
Are there any other common causes I should look into?
Cheers