8
Service Manual - Dishwasher Models DDW24S, RDW24I and RDW24S
Cables
• The machine is fitted with coded connectors to prevent
incorrect wiring. The cables comply with the Rast 2.5
and Rast 5 standards.
Main Power Switch
• The main power switch
has 2 pins and breaks
the phase and the earth.
However, power to the
filters, overflow guard,
drain pump and inlet
valve is not cut when
the main power switch is
turned off. On the RDW
series models, the main
power switch is electron-
ic and is integrated with
the control unit. The machine switches to standby when
the main power switch is deactivated and when the
door is closed. Standby is deactivated when the main
power switch is activated and when the door is opened.
Terminal Block with EMC Filter and
Inductor
• The filter is fitted at the front of the bottom plate and
consists of a number of coils, condensers and resistors.
• Purpose: To eliminate electromagnetic interference to
and from the machine.
Door Switch
• A micro switch detects when the door has been
opened. The program is paused and power to certain
components (circulation pump, valves and more) is cut.
The program continues where it left off when the door
is closed. If a program is running the machine indicates
that the door is open.
• Purpose: To prevent the machine from running while
the door is open.
Overflow Guard
• The overflow guard is integrated with the bottom drain.
This overflow guard consists of a micro switch activat-
ed by a float if water collects on the machine’s bottom
plate. The micro switch is normally closed. When it is
activated, it breaks the circuit to the CU,
• the drain pump starts, the program is interrupted and
the machine indicates an overflow. Purpose: To provide
protection from any water leaks or flooding from the
machine.
Thermistor
• The thermistor for tempera-
ture measurement is locat-
ed at the front edge of the
bottom drain. The thermis-
tor measures and controls
the water temperature,
which can be up to 70°C
(158°F). If the thermistor
short-circuits or loses con-
tact with the CU, or of the thermistor does not register
a temperature increase of 5°C (41°F) within 10 minutes
of the element being activated, the element is switched
off and a fault code is indicated. This is only indicated
in the service menu. The thermistor is of the NTC type
(Negative Temperature Coefficient), i.e. its resistance
decreases as temperature increases.
• Purpose: To control the water temperature during the
dishwashing process.
Pressure Sensor
• The pressure sensor is
connected to the pres-
sure chamber in the bot-
tom drain. It measures
the pressure, which cor-
responds to the water
level in the machine. If
the water level in the
machine is too high (for
five consecutive sec-
onds) the drain pump
starts and all other
components are switched off. When the correct level
is reached, the program continues where it left off. If
the level sensor generates an output signal of <1 VDC
during the prewash (indicating a blocked filter), an addi-
tional prewash is activated with an SCS step. The level
sensor also controls the draining time (can be extended
from 20 seconds to a maximum of 2 min). The sensor
also checks the need to refill (such as if a bowl fills with
water).
• Purpose: To prevent overflow, to detect a ‘blocked fil-
ter’, to when necessary refill the machine (such as if a
bowl has filled with water) and to control the draining
time.
Components Descriptions
DDW Main Power Switch
Thermistor
Pressure Sensor