Floorboard carpeting gets wet when running the air conditioner...suspect the drain hose to be plugged. Where is it located?

Sounds like the air conditioning evaporator/heater box has a blocked drain, when using a/c condensation will form on the evaporator, and should drain via hose externally...

The drain hose will run through the floor directly under where the a/c fan/evaporator box is located, you may have to remove some kick panels or part of dashboard to access the evaporator box to clean the drain hose....

Often the floor of the passenger side become wet if the drain pipe of the evaporator is:
- Bent or twisted.
- Clogged or,
- There is any obstruction in its routing.
The drain pipe is a rubber hose about 14 mm in diameter, located just under the evaporator (cooling coil) casing on the passenger side.
The most easiest way to clean the pipe is to take it out, wash it from inside with water or to blow a compressed air slowly through its distal end while leaving it in place under the body.
Note: Keep your eyes away while blowing the air.
Hope that it works.

check that the ac drain hose is not blocked . clean out the gunk in the ac box and ensure that the hose is clear all the way

your heater core is bad they leak when they go bad youll have to replace its under/behind the dash

Someone times there is a leak from under the seat, you should probably get it check out!

does it have a sun roof and the drains are plugged up?

Check the drain hoses. If you are getting water inside the cabin, namely on the passenger side, then you have a clogged or crimped drain hose.

Feel around the passenger side front foot well for wet carpet. Inspect all the hoses and drain plugs to make sure you remove the clog.

You are correct...Look for a small rubber hose protruding from the firewall on the passenger side about even with the bottom of the inside heater box. do not stick anything hard in there or you can damage parts. usually just working it a bit or sticking your finger in there will get it flowing again.

do you have a sun roof, if so start there, because there are two hoses at the back corners of the roof pan that allow water to drain, if they leak, they will soak the rear floorboards, and if not that check the door jam seals.(note that if the plugs on the floor are missing that will be verry hard not to have wet carpet)........let me know?

Your air conditioner water drain holes are blocked. Check the exit holes for water from the evaporator unit under the foot wells or dash unit. Through these holesor unblock these and the water will flow through to the outside