Service manual

33
Troubleshooting
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.