Heater Coolant Pump (LKN, LFV)
WARNING: This page is about a different car, the 2019 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
The heater coolant pump (heater auxiliary water pump) circulates coolant from the engine through the heater core to provide heat to the passenger compartment when the engine is not running.