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System Fan is not Operating Correctly
Issue
HP notebook PCs may display the following error message:
The system has detected that a cooling fan is not operating correctly
Error Code : 90b
Solution
It is recommended to perform a hard reset as that can sometimes restore the system fan to a normal operating condition.
Hard reset :
  1. Unplug the AC adapter from the notebook PC.
  2. Remove the computer from any port replicator or docking station, disconnect cables to printers or devices such as external monitors, USB memory sticks or SD cards, headset or external speakers, mouse or auxiliary keyboard, turn off WIFI and Bluetooth wireless devices.
  3. Remove the battery from the notebook battery compartment.
  4. Press and hold down the power button for about 15 seconds to drain any residual electrical charge from the capacitors that protect the memory.
  5. Insert the battery and plug the AC adapter back into the notebook PC, but do not connect any of the peripheral devices.
  6. Press the power button to turn the notebook PC back on.
If the system fan continues to malfunction:
  1. Unplug the AC adapter.
  2. Remove the battery.
  3. Remove the keyboard.
  4. Disconnect the fan cable from the system board.
  5. Reconnect the fan cable to the system board.
  6. Reconnect the keyboard, battery and AC adapter.
  7. Press the power button to turn the notebook PC back on.
If the system fan continues to still malfunction, replace FAN and system board because the Fan connector on system board or the zif connector of FAN can be damaged.