source of leak to front dr.side carpet/sound of water sloshing around in front

I havent noticed particularly if a/c on when I hear sloshing but will pay attention.....I think tho on second thought I still hear it when no a/c, haven't operated the a/c since weather turned cooler but wet mat on floor I'm not sure how long it's been there.

Noise could be water in HVAC case or coolant moving in heater core. Noise in heater core could be from being low or restricted. Check and make sure the wetness is water and not coolant. Does the noise happen every time you drive the car?

This sloshing sound has been constant since about Aug. 2012. I dont know how long carpet dr.side front has been wet cuz rubber mats on top of carpet to protect it so wherever water coming from its going into carpet under rubber mat as no water ever on top of rubber mat. Thank you for your responses I believe they will ultimately lead to discovery of problem(s).