36 1100 Series Nano Pump Service Manual
2 Troubleshooting and Test Functions
Fan Failed 
The cooling fan in the nano pump has failed. The hall sensor on the fan shaft is 
used by the CSM board to monitor the fan speed. If the fan speed falls below 
2 revolutions/second for longer than 5 seconds, the error message is 
generated.
Probable Causes
• Fan cable disconnected.
• Defective fan.
• Defective CSM board.
• Improperly positioned cables or wires obstructing fan blades.
Suggested Actions
✔ Ensure the fan is connected correctly.
✔ Exchange fan.
✔ Exchange the CSM board. 
✔ Ensure the fan is not mechanically blocked.