SQFlex Service Instructions
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Trouble-shooting by means of CU 200
Indication/Fault Possible cause Remedy
1. No light in front 
cover.
Pump does not 
deliver water.
No voltage supply.
• Reestablish the voltage supply.
Position of ribbon cable 
connector is wrong or
cable is defective.
• Correct the position of the cable or replace it.
2. No light in front 
cover, and pump 
does not deliver 
water. But the LEDs 
inside CU 200 indi-
cating 5 V, 10 V and 
24 V internal supply 
voltage are on, and 
the ‘CONTROL 
INDICATOR’ LED is 
not flashing.
CU 200 is defective. • Replace the CU 200.
3. Pump does not start.
Green indicator light 
in ON/OFF button is 
on.
No fault indicated.
CU 200 or pump is defec-
tive.
• Check that the ‘CONTROL INDICATOR’ LED is 
flashing. If not, replace the CU 200.
• Check that there is sufficient voltage on the 
PUMP terminals. If no voltage can be measured, 
replace the CU 200.
If a supply voltage to the pump can be detected, 
continue as follows:
• Switch off the energy supply and wait for one 
minute.
• Switch on the energy supply and observe what 
happens:
If the green indicator light in the ON/OFF button 
is on and the pump still does not start, the pump 
or pump cable is defective. 
• Repair or replace pump or cable.
4. Off light in the ON/
OFF button is on.
Pump has been stopped.
• Press the ON/OFF button on the CU 200 to start 
the pump.
5. CU 200 indicates 
‘F3 = no contact to 
pump’.
CU 200 defective.
• Check
- the connection in the CU 200
- the pump cable
- the end cover with socket on the pump.
Pump cable or connec-
tions defective.
Pump is defective.
• Repair or replace the pump.
6. CU 200 indicates 
‘F1 = overvoltage’
Supply voltage is above 
permissible range.
• Disconnect the solar modules to allow the volt-
age to drop.
• Reconfigure the modules and reconnect them.
If a different supply source is used, check that 
the voltage is within the recommended voltage 
range.
Note: As the voltage is detected at the motor, allow 
for the voltage drop in the pump cable.
7. CU 200 indicates 
‘F2 = overtempera-
ture’.
Too high water tempera-
ture.
• Ensure that the water temperature is below the 
maximum permissible level.
Incrustations on motor.
• Remove incrustations on the motor.
Pump is defective.
• Repair or replace the pump.
sqflex_SI_US_WG.book Page 10 Thursday, October 1, 2009 3:27 PM










