Cooling System: Description and Operation

Cooling System Description and Operation

This vehicle is equipped with three fully independent cooling systems. The power electronics cooling system is dedicated to cooling the battery charger and the power inverter module. The battery cooling system is dedicated to cooling and heating the high voltage battery. The engine cooling system is dedicated to cooling the engine and providing heat to the passenger compartment.

Engine Cooling System Description and Operation

The engine cooling system consists of a radiator, two 12 volt pulse width modulated (PWM) radiator fans, a 12 volt coolant pump, a coolant flow control valve, a high voltage heater and a heater core.

The Hybrid Powertrain Control Module 2 (HPCM2) uses serial data to signal the ECM to operate the radiator fans in response to the need for air flow for the power electronics radiator or the battery radiator. The ECM uses this request from the HPCM2, along with other inputs such as the need for engine cooling, to make the final decision on how fast to run the radiator fans. The ECM transmits this fan speed command back to the HPCM2 using both a PWM hardwire signal and via serial data.

The HVAC Control Module turns on the coolant pump and monitors the temperature sensors in the passenger compartment, engine radiator, high voltage heater and the engine to determine the position of the coolant flow control valve and if the high voltage heater is needed. Passenger compartment heat is provided by air flowing through the heater core. The heater core is heated by coolant from either the engine or the high voltage heater.

The engine cooling system circulates a 50/50 mixture of Dex-cool and distilled water.