I'd check the outlet pipe with a wire hanger. If a mud wasp has made a home up in there you will find the water dripping back into your house through the unit itself. And does that make a mess. Ours got blocked up and dripped down onto the top of the curtain which was covered with a felt like material to black out the window for when hubs did night shift. Didn't notice the wet mark but then we got the smell from the carpets which had soaked up the water. Had to strip them back dry out the boards then shampoo and clean the carpet. and dry it out.
