Traction Battery Cooling System Overview
AUXILIARY COOLING SYSTEMTRACTION BATTERY COOLING SYSTEM OVERVIEW
The air conditioning (A/C) system has been modified to provide cooing to the traction battery in addition to the passenger compartment cooling function. A traction battery cooling request to the PCM results in the engine turning on in order to drive the compressor.
- A serviceable air filter is accessible in the left rear interior panel.
- The A/C system has two parallel refrigerant loops; one for passenger compartment and a new one for the traction battery cooling unit evaporator.
- Each refrigerant loop has its own shutoff valve.
- The A/C system can cool each zone independently of the other.
- A single compressor is used to pump refrigerant through both loops. The A/C compressor and the condenser on the Tribute Hybrid are different than the Tribute to handle the change in capacity.
- An air temperature thermistor was added to the front and rear A/C systems to control compressor cycling.
- The TBCM requests A/C, controls the battery refrigerant solenoid valve, and sends the evaporator temperature status and solenoid status to the PCM.
- The TBCM is built into the battery case and is not serviceable.
- The TBCM communicates with the PCM over the CAN.
- The TBCM controls the airflow mode actuator on the rear A/C cooling unit. This electric actuator moves two baffles to use either outside air or recirculated air to cool the traction battery.
- The air inlet for the traction battery cooling unit is in the left rear quarter window. The air outlet is below the inlet and behind the bumper.
TRACTION BATTERY COOLING SYSTEM STRUCTURAL VIEW
Traction Battery Cooling System Structural View:
AUXILIARY CLIMATE CONTROL HOUSING
Auxiliary Climate Control Housing:
FRESH AIR INTAKE AND OUTLET LOCATIONS
Fresh Air Intake And Outlet Locations:
TRACTION BATTERY CONTROL MODULE (TBCM)
The TBCM controls the battery temperature by activating or deactivating the fans contained within the High Voltage Traction Battery (HVTB) and by sending an A/C request signal to the PCM, if required. The TBCM also monitors the auxiliary evaporator discharge air temperature sensor and sends a signal to the PCM for A/C compressor and battery zone valve operation.
The TBCM is an integral part of the HVTB.
AUXILIARY EVAPORATOR DISCHARGE AIR TEMPERATURE SENSOR
The auxiliary evaporator discharge air temperature sensor contains a thermistor which communicates the auxiliary evaporator air discharge temperature to the TBCM. The TBCM then sends a signal to the PCM to indicate if the auxiliary discharge air temperature signal is indicating a freeze or no-freeze condition.
When the A/C is operating for HVTB cooling, but has not been requested for the passenger compartment, the PCM prevents icing of the auxiliary evaporator core. It does this by switching off the A/C compressor when the TBCM indicates the auxiliary evaporator discharge air temperature sensor reading has fallen below acceptable levels, and by switching on the A/C compressor when the auxiliary evaporator temperature rises above acceptable levels.
When the A/C is operating for both the passenger compartment and HVTB cooling, the A/C compressor will continue to run (A/C request will remain ON), and the battery zone valve will be closed by the PCM if the auxiliary evaporator discharge air temperature sensor is reading a temperature below acceptable levels. This allows continued refrigerant flow to the front (main) evaporator core, while allowing the auxiliary evaporator core to warm to acceptable levels.
The evaporator discharge air temperature sensor is located on the auxiliary climate control housing.
BATTERY ZONE VALVE
The battery zone valve is a solenoid-type valve used by the PCM to isolate the auxiliary evaporator from the refrigerant system, when the A/C compressor is operating for passenger compartment cooling and A/C operation has not been requested for HVTB cooling. When A/C operation is requested for HVTB cooling, the battery zone valve will also be closed to prevent freezing of the auxiliary of the auxiliary evaporator core if the auxiliary evaporator discharge air temperature sensor indicates that the auxiliary evaporator temperature has fallen below acceptable levels, while the front (main) evaporator discharge temperature sensor is reading within acceptable levels. This is done to prevent the A/C compressor having to be cycled off when passenger compartment cooling is still required.
The battery zone valve is mounted to the bottom of the auxiliary climate control housing.
BATTERY ZONE AIR FILTER
The auxiliary evaporator core housing contains an auxiliary battery zone air filter. This is to reduce the amount of airborne particulates entering the battery compartment. An access panel is located on the RH quarter trim panel for the battery zone air filter. The air filter is located behind the battery zone air filter cover in the auxiliary evaporator core housing.