Electrolux W465H Service Manual page 33

Fault code 28, CPU/DLCU LOW LEVELS
The DLCU contains a mechanical level monitor which ensures that there
is no water in the machine when the lock opens. To ensure that the level
monitor functions correctly, the mechanical level monitor is compared with
a nominal value generated by the CPU, which is compared with the elec-
tronic level check.
When the water level exceeds the nominal value, a check is made to
ensure that the mechanical level monitor is switched on, and if so, a fault
code is generated.
Reason:
• The level controller can be damaged:
• Cross talk in the level controller electrical system.
• Leakage in the level controller's air hoses.
• Incorrect nominal value, possibly caused by a fault in the electronic
level controller.
Action:
• Check the level controller function. (Switch-on level = 40 mm, switch-off
level = 15 mm Wg)
• Check the cables and their connections. The voltage across the level
controller should be 0 V when the water level is < 15 mm Wg and 5 V
when water level is > 40 mm Wg.
• Check that the level hoses are not blocked. Blow clean all the hoses in
the level system.
Fault code 31, HEAT SINK TOO HOT
This fault code is generated by the motor control. There is a temperature
sensor (NTC) mounted on the motor control cooling flange next to the po-
wer transistors in the output stage. If the temperature of the cooling flange
gets too high (> 90°C) the fault code will be set to protect the transistors.
The cause of high cooling flange temperature can be e.g. a stiff drum in
combination with intensive use and high ambient temperature. There may
also be a fault in the motor (sticking bearings or short circuit in windings,
which impairs the efficiency of the motor). There may also be a fault in the
motor control temperature measuring circuits.
Actions:
• Make sure the drum turns easily.
• Check the value on the fault code counter for fault code 31.
• Check the last 8 motor control fault codes.
• Start a 90°C normal program with load on continuous operation and
measure the temperature of the motor and motor control.
• Replace the defective part.
Troubleshooting
33