The 928S is standard equipped with heated windshield washing jets from 1984 model on. Heating is supplied via term. X and therefore switched on with the engine running.
A PTC resistor controls the electric power supply according to the Instantaneous jet temperature. The maxi-
mum jet temperature is 40 “C. Despite of jet heating, washing fluid will evaporate when leaving the jets and freeze in this area. Washer solvent with windshield washing antifreeze must still be used.

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The windshield washers contain tuning  with some one-way valves to seal off the lines when the pump does not run (no pressure). These valves do get corroded and stuck sometimes. If you delete the valves, the water keeps seeping out until the hose is completely empty.

This is what the valve looks like:

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Honda makes similar but less bulky Y connectors and one-way valves.