Milan FWD V6-3.0L (2010)
Auxiliary Water Pump: Description and Operation
Heating and Ventilation
The heating and ventilation system has the following features:
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Controls the temperature and, during A/C operation, reduces the relative humidity of the air inside the vehicle
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Delivers heated or cooled air to maintain the vehicle interior temperature and comfort level
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Cooling or heating can be adjusted to maintain the desired temperature
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Uses a reheat method to provide conditioned air to the passenger compartment
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All airflow from the blower motor passes through the A/C evaporator core
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Temperature blending is controlled by the temperature blend door(s), which regulate(s) the amount of air that flows through and around the heater
core, where it is then mixed and distributed
Heater Core
The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer the heat to air passing through the plenum.
Blower Motor
The blower motor pulls air from the air inlet and forces it into the heater core and evaporator core housing where it is mixed and distributed.
Heater Core and Evaporator Core Housing
The heater core and evaporator core housing directs airflow from the blower motor through the evaporator core and heater core. All airflow from the
blower motor passes through the evaporator core. The airflow is then directed through or around the heater core by the temperature blend door(s).
Vehicles equipped with dual-zone Electronic Automatic Temperature Control (EATC) use a partitioned heater core and evaporator core housing with 2
electric actuator-positioned temperature blend doors. This allows for separate temperatures to be selected for the driver and passenger sides of the
passenger compartment. Manual systems and single-zone EATC systems use a single electric actuator-positioned temperature blend door to direct
airflow through or around the heater core.
Auxiliary Coolant Flow Pump
An auxiliary coolant flow pump is used only on hybrid vehicles to improve engine coolant circulation at low engine speeds or when the engine is OFF.
The auxiliary coolant flow pump will be disabled when any of the following conditions are present:
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The climate control module is set to the OFF position.
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The ambient temperature is above 32°C (90°F).
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The coolant temperature is less than -10°C (14°F).
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The engine speed is above 4,000 rpm.
When none of the listed conditions are present, the auxiliary coolant flow pump is controlled by a strategy included in the PCM software. The control
strategy monitors the ambient temperature, coolant temperature and engine rpm. As the ambient temperature and/or coolant temperature increase, the
auxiliary coolant flow pump will shut down at lower engine speeds. For example, when both the ambient temperature is above 16°C (60°F) and the
engine coolant temperature is above 66°C (150°F), the control strategy will shut off the auxiliary coolant flow pump at 2,000 rpm. When both the
ambient temperature is above 24°C (75°F) and the engine coolant temperature is above 66°C (150°F), the control strategy will shut off the auxiliary
coolant flow pump regardless of engine speed.
To verify auxiliary coolant flow pump operation, allow the vehicle to cool in a cool location. Start the engine and let the engine idle until it shuts down
automatically. Select the FLOOR mode on the HVAC module at the highest temperature setting and HI blower speed. If the auxiliary coolant flow pump
is inoperative or is not producing adequate coolant flow, the passenger compartment air discharge temperature will quickly decrease and further
diagnosis is required. If the auxiliary coolant flow pump is operating normally, the passenger compartment air discharge temperature will remain steady,
or slowly decrease.
