WATER NOISE

I HAVE A 1997 DODGE RAM 1500 TRUCK
5.9 V8 MOTOR - AUTO TRANY - SHORT CAB & BOX
TWO WHEEL DRIVE
I HAVE A SLOSHING WATER SOUND COMING
FROM THE HEATER/AIR COND. BLOWER BOX AREA
WHERE IS THE DRAIN HOSE/HOLE
WHAT IS THE CORRECT WAY TO CLEAR IT
BLOW AIR- PUSH A WIRE- REMOVE AND CLEAN
ADDED NOTE:
THERE IS NO ANTIFREEZE SMELL COMMING FROM
THE VENTS AND I CHANGED THE RADIATOR
2 MONTHS AGO AND HAVE NOT USED ANY
ANTIFREEZE SINCE THE RADIATOR CHANGE
ALSO THERE IS NO WETNESS ON THE CARPET
THANK YOU RAY U.