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Water Inlet / Discharge System – Operation - Bosch SHI 4302 Repair Manual

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WATER SYSTEM OPERATION: Fig. 12-1 is a close up view of the complete Water Systems.
Fresh water is brought in by the Water Valve and through the Inlet Water Line, item 3. The
incoming water is then directed into the Water Level Housing Assembly, item 4, and then on to the
Sump via the Sump Fill Hose, item 8.
As the unit fills with water the Diaphragm on the Water Level Housing Assembly expands due to
the pressure of air forced up by the incoming water. When the correct water level is reached the
Diaphragm moves the Switch Lever, which in turn closes the Water Level Switch.
When the Water Level Switch closes the Water Valve shuts and the Circulation Motor is activated,
and the program advances.
Once the Circulation Motor is activated the water level will drop slightly, the unit then
calls for a small amount of additional water to be added.
OVER FILL (Fig. 12-3)
As a safety feature, if the Diaphragm were to malfunction the water level would rise and activate
the Safety Float, item 5. As the Safety Float rises it in turn closes the Float Switch, item 6. When
the Float Switch closes it activates the Drain Motor.
Service tip:
If the dishwasher repeatedly fills and drains the cause is most likely a faulty
BASE FLOAT (Fig. 12-4)
As an additional safety feature, if the Base were to fill with water due to a hose or pump leak the
Base Float, item 9, will rise and via a Float Lever and Pushrod, item 8, would close the Float
Switch, which in turn activates the Drain Motor.
Service tip: If there is water in the base the Drain Motor will run continually, but will not drain
water from the base.
Dishwashers with a Countdown Display will show an "F" in the display window when a filling fault
occurs. Filling faults can be: Water in the base; overfill; and under or no fill.
Live Dealer Display Models with "F" codes:
Since display models are hand filled, achieving the correct water level is difficult, (see Section 3,
Fig. 5-7) so the unit will perceive a filling fault and display the "F" code. This is normal, do not
attempt a repair.
When the Drain Motor is activated gray water flows from the Sump through the Sump Drain Hose,
item 2, around the Water Chamber and out through the Main Drain Line, item 1.
Water Inlet / Discharge System – Operation

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