Cause : Heat sink temperature low comes when the frequency converter is too cold to operate. This warning is based on the temperature sensor in the IGBT module.

Increase the ambient temperature of the unit. Also, a trickle amount of current can be supplied to the frequency converter whenever the motor is stopped by setting 2-00 DC Hold/Preheat Current at 5% and 1-80 Function at Stop.

1. The heat sink temperature measured as 0 °C could indicate that the temperature sensor is defective, causing the fan speed to increase to the maximum.
2. If the sensor wire between the IGBT and the gate drive card is disconnected, this warning would result.
3. Also, check the IGBT thermal sensor.