T20-T30 Servuce Manual 11/07/2014
Page 13 of 18
4.6.
TROUBLESHOOTING
– DIAGNOSTIC GUIDE:
2 FLASH CYCLE
– BELOW LOW LEVEL
Display pattern:
2 flashes then a short pause - repeated.
Electronic check and action:
This indicates that the low level circuit is open i.e. the probe is not in contact with the
water.
The element is switched OFF at this stage and the inlet is left ON.
(Note that if this is a low probe wiring fault, the water will stop at the high level probe
regardless of the status of the low level).
This is a recoverable error i.e. the machine does not need to be reset when the problem
is solved. (e.g. if a closed mains water stop valve is the problem, opening the valve will
allow water into the machine and normal function will resume when the low level probe
is reached)
Probable causes:
1. The water level is below the low level probe, which is normal when the machine fills for the first
time. (Can be flashing for up to 2 min at start up)
2. The low level probe wire is disconnected, or there is another wiring fault
(E.g. a bad earth (return) connection between the PCB and the Tank)
Action required:
1. Check that the water pressure is OK and ensure that the stop valve is open.
2. Check that the inlet solenoid is working.
3. If the water level is above the level of the low probe, check the probe circuit wiring
3 FLASH CYCLE
– THERMISTOR OPEN CIRCUIT
Display pattern:
3 flashes then a short pause - repeated.
Electronic check:
This indicates that the Thermistor is measuring such a large resistance that it assumes
the thermistor circuit is open.
The element and inlet valve are turned OFF when this error is detected
This is a recoverable error. When the correct range of resistance is measured, normal
operation resumes
Probable causes:
1. The thermistor probe is unplugged from the 4way connector on the PCB or the thermistor has
failed open circuit.
Action required:
1. Check that the thermistor is plugged in to the PCB correctly. If it is, replace the thermistor.
4 FLASH CYCLE
– NOT HEATING
Display pattern:
4 flashes then a short pause - repeated.
Electronic check:
This checks that the temperature is increasing when the heater is on.
Measures the rate that the temperature increases in a specified time. This error is only
displayed after 20 mins of the heater being on continuously. When the error is detected,
the element and inlet valve are turned off.
This is a non recoverable error. The machine needs to be reset when this problem is
solved.
Probable causes:
1. The elements have failed
2. Wiring fault