The start and stop behavior seen at system startup is normal. This is the result of using a new controller in the fan beginning 2012, which senses the fan rotor position at startup.
- These fans are operating as expected, the fan starts and stops for three to five seconds at system startup.
- The controller pulses the rotor two times to establish the rotor position, verifies the rotation direction, and then starts.
- After starting, the fan quickly ramps to full speed and then assumes normal speed per the operating conditions.
This applies to: