We have a 2005 civic and water is leaking onto the passenger side floor when making left turn and at other times. We hear water sloshing around in the dash. We are looking for the hose that drains water from the box under the passenger dash into the engine compartment, so that we can see if it is clogged, but we do not see a hose. We have seen others write about this problem, but we just can't find a hose. How do we find it? Thanks.

Could be the drain tube is partially clogged. It is usually located on the fire-wall or down towards the floor pan under the car. It is usually close to where the A/C lines go thru the fire-wall. About 1/2 inch diameter sticking straight out but may have a 90 degree elbow pointing down.
Also, it's been extra hot and humid all over and moisture could be freezing inside the unit when on MAX A/C, then suddenly melting when switched to normal. This opens the outside air door and allows warm/hot air into the unit instead of recirculating the cold air inside the car. The drain may not be able to handle a large, sudden quantity of water.
Perform a "driveway" test. Open the hood, start engine and run the A/C on normal with the windows or doors open. Locate the drain tube by looking for water dripping. Once located twist 2 or 3 pipe cleaners together and verify the tube is clean. Then close the doors/windows and switch to MAX A/C. Check for water dripping. If it stops dripping, water is freezing inside and now you know why!