Evaporator Fan Control
The controller determines evaporator fan motor speed based on the setpoint temperature and the mode setting.
Chill Loads (Setpoints of -9.9 C [14.1 F] and Above)
When the Optimized Mode is set to ON, the evaporator fans operate on low and high speed as needed to maintain the setpoint and save energy. Typically, the evaporator fans run in high speed during the initial pull-down to setpoint, but the evaporator fans may run in low speed at times during pull-down as determined by the controller. Once the setpoint has been reached, the evaporator fans usually run in low speed as long as the temperature is near the setpoint. If the controller determines it is necessary, the evaporator fans may shift back to high speed temporarily to bring the temperature back to setpoint or increase air circulation.
When the Non-Optimized mode is set to On, the evaporator fans operate continuously on high speed.
Frozen Loads (Setpoint at -10.0 C [14.0 F] or Below)
When the Optimized mode is set to On, the evaporator fans operate on low speed on and off. The evaporator fans run in low speed when the compressor is running. When the compressor is not running the evaporator fans are usually off, but periodically run in low speed to circulate air to evaluate when to start the compressor again.
When the Non-Optimized mode is set to On, the evaporator fans operate continuously on low speed.