Where is the entrance of a6 heating box?

The water inlet of a6 heater box is under the dashboard. According to relevant public information, the water tank of the engine is located behind the front bumper, and the water inlets of the heater box and a6 heater box are below the instrument panel. Below is the water inlet pipe. There is a water tank in the gantry in front of Audi a6 (the mechanic calls it the water tank). There are two pipes, one connected from the lower left corner or the lower right corner, and the other in the upper left corner or the upper right corner. There is a cover on the pipe. Below is the water inlet pipe, and above is the water outlet pipe.