Asko DW90 Series Service Manual page 11

Service manual DW90
Component description
Flow meter
The flow meter is fitted in the air gap and
cannot be replaced separately. It comprises an
impeller that is rotated by the flow of water
from the inlet valve. The impeller is fitted with
two magnets that affect a sensor, a so-called
reed switch. This is connected to the control
unit via a wire and provides the control unit
with information on the amount of water
entering the machine. In order for the flow
sensor to function normally the incoming
water pressure must be at least 2 bar (29 psi).
Output signal: 220 pulses per liter (0.26 gallon)
of water flowing through.
Circulation pump
The circulation pump comprises an asynchronous
motor with a capacitor and a pump housing with
an impeller. The impeller and seals cannot be
replaced separately, rather the entire pump must
be replaced. The circulation pump can be rated
220-240V, 50/60Hz, as well as 120V, 60Hz.
Purpose: To provide the spray system with the
water pressure necessary for the dishwashing
process.
Flow meter
Spray arm diverter
The spray arm diverter is under the spray arm hub
on the underside of the cleaning compartment.
The water from the circulation pump flows
through the spray arm diverter, which alternates
the flow of water between the upper and lower
spray arms. The spray arm diverter comprises a
synchronous motor that drives a disc valve. The
disc has a smaller opening and a larger opening and
as it rotates it distributes the water to the spray
arms at low or high pressure. Information on the
disc position is sent to the control unit. The spray
arm diverter is calibrated when the main power
switch is turned on.
Purpose: To distribute spray water to the spray
arms in accordance with the program specification.
Heating element
The heating element is of the flow-through
type and is fitted between the bottom drain
and the suction connector of the circulation
pump. It comprises a pipe with a heating coil.
One side of the heating coil is fitted with an
overheating cut-out with a trigger temperature
of 98°C (208°F) and an automatic reset. The
other side is fitted with a safety fuse that blows
at 229°C (444°F). The element is replaced
from the rear of the machine by first moving
the circulation pump out of the way.
Purpose: To heat the dishwater to the correct
temperature during the prewash/main wash and
final rinse.
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