Nissan Pathfinder. Manual - part 688
COMPONENT PARTS
HAC-13
< SYSTEM DESCRIPTION >
[AUTOMATIC AIR CONDITIONING]
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HAC
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Air mix door motor (Driver side)
The air mix door controls the mix of hot or cold air that enters the ventilation system. It is con-
trolled by the A/C auto amp. based on the position of the temperature dial. The air mix door mo-
tor receives position commands from the A/C auto amp. and reports actual door position back
via an LCU (Local Control Unit) installed inside the motor. Commands and responses are sent
across the LIN (Local Interconnect Network) to each motor simultaneously, with each motor
having its own unique address, thereby only responding to requests sent to its specific address.
The LCU reads the door position from a Position Balanced Resistor (PBR), also part of the mo-
tor, and returns that information to the A/C auto amp. The LCU switches the polarity of the cir-
cuits connected to the DC motor to drive the motor forward or backward as requested by the
front air control. If the air mix door moves to a position less than 5% or more than 95% of its
expected or allowed positions, the A/C auto amp. will set a DTC.
Air mix door motor (Passenger side)
The air mix door controls the mix of hot or cold air that enters the ventilation system. It is con-
trolled by the A/C auto amp. based on the position of the temperature dial. The air mix door mo-
tor receives position commands from the A/C auto amp. and reports actual door position back
via an LCU (Local Control Unit) installed inside the motor. Commands and responses are sent
across the LIN (Local Interconnect Network) to each motor simultaneously, with each motor
having its own unique address, thereby only responding to requests sent to its specific address.
The LCU reads the door position from a Position Balanced Resistor (PBR), also part of the mo-
tor, and returns that information to the A/C auto amp. The LCU switches the polarity of the cir-
cuits connected to the DC motor to drive the motor forward or backward as requested by the
front air control. If the air mix door moves to a position less than 5% or more than 95% of its
expected or allowed positions, the A/C auto amp. will set a DTC.
Ambient sensor
The ambient sensor measures the temperature of the air surrounding the vehicle. The sensor
uses a thermistor which is sensitive to the change in temperature. The electrical resistance of
the thermistor decreases as temperature increases.
AV control unit
AV control unit transmits A/C and AV switch assembly operation signal to A/C auto amp. via
CAN communication line.
BCM
BCM transmits blower motor ON signal to the front and rear blower motor relays.
Display unit
(except base audio system)
The display unit indicates operation status of the front and rear automatic air conditioning sys-
tem.
ECM
The ECM sends a compressor ON request to the IPDM E/R based on the status of engine op-
eration and load as well as refrigerant pressure information. If all the conditions are met for A/
C operation, the ECM transmits the compressor ON request to the IPDM E/R. The ECM shares
the refrigerant pressure sensor signal, engine RPM, and engine coolant temperature with the
A/C auto amp. via CAN communication line.
Front blower motor
The front blower motor varies the speed at which the air flows through the ventilation system.
Front blower motor relay
The front blower motor relay controls the flow of current to fuse 17 and 27 in the Fuse Block (J/
B). The relay is connected directly to ground, and is controlled by the BCM.
Fuse block (J/B)
Located in the passenger compartment, behind the left lower IP, the Fuse Block (J/B) contains
the front blower motor relay and several fuses required for the air conditioner control system.
IPDM E/R
A/C relay is integrated in IPDM E/R. IPDM E/R operates A/C relay when A/C compressor re-
quest signal is received from ECM via CAN communication line.
Intake door motor
The intake door motor controls the position of the intake door. Fresh air is allowed to enter the
cabin in one position, and recirculated inside air is allowed to enter in the other position. At times
the A/C auto amp. may command partial fresh or recirculation based on evaporator or coolant
temperatures. The intake door motor receives position commands from the front air control and
reports actual door position back via an LCU (Local Control Unit) installed inside the motor.
Commands and responses are sent across the LIN (Local Interconnect Network) to each motor
simultaneously, with each motor having its own unique address, thereby only responding to re-
quests sent to its specific address. The LCU reads the door position from a Position Balanced
Resistor (PBR), also part of the motor, and returns that information to the front air control. The
LCU switches the polarity of the circuits connected to the DC motor to drive the motor forward
or backward as requested by the front air control. If the recirculation door moves to a position
less than 5% or more than 95% of its expected or allowed positions, the front air control will set
a DTC.
Intake sensor
Intake sensor measures temperature of front evaporator fin temperature. The sensor uses a
thermistor which is sensitive to the change in temperature. The electrical resistance of the ther-
mistor decreases as temperature increases.
Component
Description