Nissan Sentra manuals

Nissan Sentra Service Manual: System description

Component parts

Component part location



  1. ECM
  2. IPDM E/R
  3. BCM (view with instrument panel removed)
  4. A/C auto amp. (view with A/C switch assembly removed)
  5. A/C switch assembly
  6. A/C Compressor
  7. Refrigerant pressure sensor (view with front bumper fascia removed)
  8. Ambient sensor
  9. Sunload sensor
  10. In-vehicle sensor
  11. Blower motor relay
  12. Blower motor (view with front A/C assembly removed from vehicle)
  13. Air mix door motor RH
  14. Mode door motor
  15. Intake door motor
  16. Air mix door motor LH
  17. Intake sensor
  18. Variable blower control

Component description

Component

Description

A/C auto amp. A/C auto amp. controls front automatic air conditioning system by inputting and calculating signals from each sensor and each switch.
A/C Compressor Vaporized refrigerant is drawn into the A/C compressor from the evaporator, where it is compressed to a high pressure, high temperature vapor. The hot, compressed vapor is then discharged to the condenser.
A/C switch assembly The A/C switch assembly controls the operation of the A/C and heating system based on inputs from the temperature control knob, the mode switches, the blower control dial, the ambient temperature sensor, the intake sensor, and inputs received from the ECM across the CAN. Diagnosis of the A/C switch assembly can be performed using the CONSULT.
Air mix door motor LH The air mix door controls the mix of hot or cold air that enters the ventilation system. It is controlled by the A/C auto amp. based on the position of the temperature dial. The air mix door motor LH receives position commands from the A/C auto amp.
Air mix door motor RH The air mix door controls the mix of hot or cold air that enters the ventilation system. It is controlled by the A/C auto amp. based on the position of the temperature dial. The air mix door motor RH receives position commands from the A/C auto amp.
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.
BCM The BCM receives the fan ON and A/C ON signals from the A/C auto amp. and sends a compressor ON request to the ECM.
Blower motor The blower motor varies the speed at which the air flows through the ventilation system.
Blower motor relay The blower motor relay controls the flow of current to fuse 20, 21 and 22 in the Fuse Block (J/B). The relay is connected directly to ground, and is energized when the ignition switch is in the ON or START position.
ECM The ECM sends a compressor ON request to the IPDM E/R based on the status of engine operation 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
Fuse Block (J/B) Located in the passenger compartment, behind the left lower IP, the Fuse Block (J/B) contains the blower motor relay and several fuses required for the air conditioner control system.
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 A/C auto amp. and reports actual door position back via an LCU (Local Control Unit) installed inside the motor. The LCU reads the door position from a Position Balanced Resistor (PBR), also part of the motor, and returns that information to the A/C auto amp. The LCU switches the polarity of the circuits connected to the DC motor to drive the motor forward or backward as requested by the A/C auto amp.

Intake sensor The intake sensor measures the temperature of the front evaporator fins. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.
In-vehicle sensor In-vehicle sensor measures temperature of intake air that flows through aspirator to passenger room.

The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.

IPDM E/R Refer to PCS-7, "RELAY CONTROL SYSTEM : System Description".
Mode door motor The mode door controls the direction the conditioned air passes through the ventilation system.

Through a series of levers and gears, the mode door controls the defrost door, the foot door, and the vent door. There are 5 preset positions: VENT, B/L, FOOT, D/F, and DEF. The FOOT position can be set to allow some airflow through to the defroster vent, or to completely block the defroster vent using the CONSULT. The mode door motor receives position commands from the A/C auto amp.

Refrigerant pressure sensor Refer to EC-29, "Refrigerant Pressure Sensor".
Sunload sensor Sunload sensor measures sunload amount. This sensor is a dual system so that sunload for driver side and passenger side are measured separately. This sensor converts sunload amount to voltage signal by photodiode and transmits to A/C auto amp.

System

System diagram

System description


System description

Control by A/C auto amp.

Ambient sensor (setting temperature correction)

In-vehicle sensor [in-vehicle temperature correction]

Intake sensor (intake temperature correction)

Sunload sensor (sunload amount correction)

Set temperature correction

A/C auto amp. performs correction to the target temperature set by the temperature control switch so as to match the temperature felt by the passengers depending on the ambient temperature detected by the ambient sensor, and controls it so the in-vehicle temperature is always the most suitable.

Control by ECM

Refer to EC-47, "COOLING FAN CONTROL : System Description".

Refer to EC-46, "AIR CONDITIONING CUT CONTROL : System Description".

Control by IPDM E/R

Refer to PCS-7, "RELAY CONTROL SYSTEM : System Description".

Refer to EC-47, "COOLING FAN CONTROL : System Description".

Control by BCM

Refer to BCS-8, "BODY CONTROL SYSTEM : System Description".

Air flow control

DESCRIPTION

AUTOMATIC AIR FLOW CONTROL

STARTING AIR FLOW CONTROL


STARTING AIR FLOW CONTROL

LOW COOLANT TEMPERATURE STARTING CONTROL


LOW COOLANT TEMPERATURE STARTING CONTROL

If the engine coolant temperature is 56В°C (133В°F) or less, to prevent a cold discharged air flow, A/C auto amp. suspends blower motor activation for a maximum of 150 seconds depending on target air mix door opening angle. After this, blower motor control signal is increased gradually, and blower motor is activated.

HIGH IN-VEHICLE TEMPERATURE STARTING CONTROL


HIGH IN-VEHICLE TEMPERATURE STARTING CONTROL

When front evaporator fin temperature is high [intake sensor value is 35В°C (95В°F) or more], to prevent a hot discharged air flow, A/C auto amp. suspends blower motor activation for approximately 3 seconds so that front evaporator is cooled by refrigerant.

FAN SPEED CONTROL AT DOOR MOTOR OPERATION

When mode door motor is activated while air flow is more than the specified value, A/C auto amp. reduces fan speed temporarily so that mode door moves smoothly.

Air inlet control

The intake door is automatically controlled by the temperature setting, ambient temperature, in-vehicle temperature, intake temperature, amount of sunload and ON/OFF operation of the compressor.

Intake door automatic control selects FRE, 20% FRE, or REC depending on a target air mix door opening angle, based on in-vehicle temperature, ambient temperature, and sunload.

Air outlet control


Air outlet control

Compressor control


Compressor control

DESCRIPTION

COMPRESSOR PROTECTION CONTROL AT PRESSURE MALFUNCTION

When high-pressure side value that is detected by refrigerant pressure sensor is as per the following state, ECM requests IPDM E/R to turn A/C relay OFF and stops the compressor.

COMPRESSOR OIL CIRCULATION CONTROL

When the engine starts while the engine coolant temperature is 56В°C (133В°F) or less, ECM activates the compressor for approximately 6 seconds and circulates the compressor lubricant once.

LOW TEMPERATURE PROTECTION CONTROL

AIR CONDITIONING CUT CONTROL


AIR CONDITIONING CUT CONTROL

When set engine is running is excessively high load condition, ECM requests IPDM E/R to turn A/C relay OFF, and stops the compressor. Refer to EC-46, "AIR CONDITIONING CUT CONTROL : System Description".

Door control

AIR MIX DOOR MOTOR (DRIVER SIDE)

DESCRIPTION

DRIVE METHOD

AIR MIX DOOR MOTOR (PASSENGER SIDE)


AIR MIX DOOR MOTOR (PASSENGER SIDE)

DESCRIPTION

DRIVE METHOD

MODE DOOR MOTOR


MODE DOOR MOTOR

DESCRIPTION

Drive method

Intake door motor


Intake door motor

Switches and their control function


Switches and their control function


  1. Intake door
  2. Blower motor
  3. Air conditioner filter
  4. Evaporator
  5. Upper air mix door (driver side/passenger side)
  6. Lower air mix door (driver side/passenger side)
  7. Heater core
  8. Foot door
  9. Side ventilator door
  10. Sub defroster door
  11. Center ventilator and defroster door

Recirculation airFresh air intake


Discharge air Recirculation air


Defroster Discharge air


Center ventilator Defroster


Side ventilator Center ventilator


Rear ventilator Side ventilator


Front foot Rear ventilator


Rear foot Front foot


Rear foot


*: Inlet status is displayed by indicator during activating automatic control


*: Inlet status is displayed by indicator during activating automatic control

Air distribution

Temperature control


Temperature control

Fail-safe


Fail-safe

FAIL-SAFE FUNCTION

If a communication error exists between the A/C auto amp., and the AV control unit and preset switch for 30 seconds or longer, air conditioning is controlled under the following conditions:

A/C switch : ON

Air outlet : AUTO

Air inlet : FRE (Fresh air intake)

Blower fan speed : AUTO

Set temperature : Setting before communication error occurs

OPERATION

Switch Name and Function

CONTROL OPERATION

A/C Switch Assembly


  1. Temperature control switch (driver side)
  2. ON/OFF switch
  3. AUTO switch
  4. Fan control switch
  5. A/C switch
  6. DUAL switch
  7. Temperature control switch (passenger side)
  8. Recirculation switch
  9. Fresh air switch
  10. Display
  11. Mode switch
  12. Defroster switch

Switch Operation



Diagnosis system (A/C AUTO AMP.)


Diagnosis system (A/C AUTO AMP.)

Description

Air conditioning system performs self-diagnosis, operation check, function diagnosis, and various settings using diagnosis function of each control unit.

Consult Function (HVAC)


Consult Function (HVAC)

Consult can display each diagnosis item using the diagnosis test modes as shown.

Consult application items

Self-diagnostic result


Self-diagnostic result

Refer to hac-38, "dtc index".

Display item list


*: Perform self-diagnosis under sunshine. When performing indoors, aim a


*: Perform self-diagnosis under sunshine. When performing indoors, aim a light (more than 60 w) at sunload sensor, otherwise self-diagnosis reports an error even though the sunload sensor is functioning normally.

Data monitor

Display item list


Work support


Work support

Note:


Note:

When the battery cable is disconnected from the negative terminal or when the battery voltage becomes 10v or less, the setting of work support may be cancelled.

Active test

HVAC test


HVAC test

Note:


Note:

Perform the inspection of each output device after starting the engine, because the a/c compressor has been operating.

DIAGNOSIS SYSTEM (BCM)

Common item

COMMON ITEM : CONSULT Function (BCM - COMMON ITEM)

Application item

Consult performs the following functions via can communication with bcm.

System application


System application

BCM can perform the following functions.

Air conditioner


Air conditioner

AIR CONDITIONER : CONSULT Function (BCM -AIR CONDITIONER)

Data monitor

DIAGNOSIS SYSTEM (IPDM E/R)


DIAGNOSIS SYSTEM (IPDM E/R)

Diagnosis Description

AUTO ACTIVE TEST

Description

In auto active test, the ipdm e/r sends a drive signal to the following systems to check their operation.

Operation Procedure

Note:

Never perform auto active test in the following conditions.

  1. Close the hood and lift the wiper arms from the windshield. (Prevent windshield damage due to wiper operation)

Note:

When auto active test is performed with hood opened, sprinkle water on windshield beforehand.

  1. Turn the ignition switch off.
  2. Turn the ignition switch on, and within 20 seconds, press the driver door switch 10 times. Then turn the ignition switch off.
  3. Turn the ignition switch on within 10 seconds. After that the horn sounds once and the auto active test starts.
  4. After a series of the following operations is repeated 3 times, auto active test is completed.

Note:

Inspection in auto active test

When auto active test is actuated, the following operation sequence is repeated 3 times.

Concept of auto active test


Concept of auto active test


Diagnosis chart in auto active test

Consult  Function (IPDM E/R)


Consult  Function (IPDM E/R)

APPLICATION ITEM

Consult performs the following functions via can communication with ipdm e/r.


ECU Identification


ECU Identification

The IPDM E/R part number is displayed.

SELF DIAGNOSTIC RESULT

Refer to PCS-20, "DTC Index".

DATA MONITOR

ACTIVE TEST


ACTIVE TEST


CAN DIAG SUPPORT MNTR


CAN DIAG SUPPORT MNTR

Refer to LAN-13, "CAN Diagnostic Support Monitor".

Preparation
Special service tool The actual shape of the tools may differ from those illustrated here. Commercial service tool ...

ECU diagnosis information
A/C AUTO AMP Reference Value VALUES ON THE DIAGNOSIS TOOL TERMINAL LAYOUT PHYSICAL VALUES DTC Inspection Priority Chart If some DTCs are displayed at the same time, perform ...

Other materials:

System
Body control system Body control system : system description OUTLINE BCM (Body Control Module) controls the various electrical components. It inputs the information required to the control from CAN communication and the signal received from each switch and sensor. BCM has combination ...

Diagnosis system (BCM) (without intelligent key system)
Common item COMMON ITEM : CONSULT Function (BCM - COMMON ITEM) Application item Consult performs the following functions via can communication with bcm. Direct diagnostic mode Description Ecu identification The BCM part number is displayed. Self diagnostic result ...

Event Data Recorders (EDR)
This vehicle is equipped with an Event Data Recorder (EDR). The main purpose of an EDR is to record, in certain crash or near crash-like situations, such as an air bag deployment or hitting a road obstacle, data that will assist in understanding how a vehicle’s systems performed. The EDR is ...

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