Evaporator Drain Tube: Description and Operation
CONDENSATION DRAIN TUBECondensation that accumulates in the evaporator housing is drained from a tube through the dash and on to the ground. This tube must be kept open to prevent condensate water from collecting in the bottom of the housing.
The tapered end of the drain tube is designed to keep contaminants from entering the heater A/C unit housing. If the tube is pinched or blocked, condensate cannot drain, causing water to back up and spill into the passenger compartment. It is normal to see condensate drainage below the vehicle. If the tube is damaged, it should be replaced.