Component Description - Hotpoint Ultima FDW85 Service Information

COMPONENT DESCRIPTION

Fill Valve
The appliance has an electromagnetically operated solenoid valve, which is connected to the water
supply. As the machine fills, a quantity of water is diverted into the fill tank for later use in the
regeneration sequence. A typical fill sequence is as follows:
The water turbine fills the dishwasher with 2 litres of water. If the pressure switch contacts are then
closed, then the turbine fills with another 2 litres of water to complete the fill. If, after the initial 2 litre
fill, the pressure switch contacts are still open, the dishwasher will fill to a maximum of 6 litres.
This initialises the filter cleaning procedure.
Pressure Switch
The pressure switch controls the overall volume of water inside the tub and signals if the heater can
be turned on.
Anti Flood Device
Consisting of a polystyrene float and microswitch. An excess of water in the base panel operates the
float switch sending a signal to the control module operating the drain pump and displaying a fault
code on the console.
Control Module
Mounted on the console, this is an electronic device that monitors and controls all devices within the
appliance.
Water Turbine
Consisting of a fixed reed switch and a magnet fitted to an impeller. Unlike previous control systems,
water fill is no longer dependant on the operation of the pressure switch. The turbine generates a
series of impulses as the water rotates the impeller vanes.
The control module translates these impulses into litres of fill water (217 impulses is equal to 1 litre
of water). The turbine also regulates the maximum amount of water that can enter the tub, therefore
acting as an overflow device. If the turbine fills the dishwasher with 2 litres of water and the pressure
switch contacts are open, the pressure switch alarm is activated. If the turbine is faulty, then the
pressure switch will control the fill. However, at the end of the cycle, the turbine faulty alarm will be
displayed.
Detergent & Rinse Aid Dispenser
Detergent and rinse aid is automatically released during the programme.
The release mechanism is activated by means of a solenoid. This in turn operates a plunger and lever
assembly, thus releasing detergent or rinse aid as required.
Circulation Pump Motor
The motor used is a capacitor run motor. The pump housing is bolted to the motor body with the
stainless steel shaft passing through a face seal in the pump with the pump impeller, with a ceramic
seal counterface, mounted directly on the shaft.
Drain Pump
This is a separate unit fixed to the sump moulding. It is operated by means of a synchronous motor
and is controlled by the control module.
Heater
The heater is encased in a metal housing with integral safety cut-out, attached via hoses to the sump
and the circulation motor.
Thermistor
Situated on the inner door panel adjacent to the dispenser. A temperature rise in the water is
converted to a changing resistance value.
A rise in temperature will give a lower resistance across the terminals of the thermistor; the control
module monitors this value and when it is the same as that as defined in the programme selected,
the module will advance the programme out of the heating stage.
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