Nissan Sentra B18 (2020-2025) Service Manual / Ventilation, Heater & Air Conditioner / Heater & Air Conditioning Control System :: Automatic Air Conditioner / Basic Inspection

Nissan Sentra B18 (2020-2025) Service Manual: Basic Inspection

Diagnosis and Repair Workflow

Work Flow

Work Flow

OVERALL SEQUENCE

DETAILED FLOW

INTERVIEW CUSTOMER
1. Interview the customer to obtain as much information as possible about the conditions and environment under which the malfunction occurred.
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GO TO 2.
SYMPTOM CHECK
1. Verify symptoms.
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GO TO 3.
CHECK FOR DTCS
1. CONSULT
  1. Ignition switch ON.
  2. Select “Self Diagnostic Result” mode of “HVAC”.
  3. Check DTC.
Is any DTC detected?
YES >>
GO TO 4.
NO >>
GO TO 5.
TROULE DIAGNOSIS BY DTC
1. Perform the diagnostic procedure for the detected DTC. Refer to DTC Inspection Priority Chart.
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GO TO 7.
OPERATION CHECK
1. Perform the operation check. Refer to Work Procedure.
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GO TO 6.
SYMPTOM DIAGNOSIS
1. Check the symptom diagnosis table. Refer to Diagnosis Chart By Symptom.
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GO TO 8.
VERIFY REPAIR
1. CONSULT
  1. Ignition switch ON.
  2. Select “Self Diagnostic Result” mode of “HVAC”.
  3. Check DTC.
Is any DTC detected?
YES >>
GO TO 4.
NO >>
GO TO 8.
PERFORM FINAL OPERATION CHECK
1. Perform the operation check. Refer to Work Procedure.
Does it operate normally?
YES >>
Inspection End.
NO >>
GO TO 2.

Operation Inspection

Work Procedure

Work Procedure

DESCRIPTION

The purpose of the operational check is to check that the individual system operates normally.

Conditions

: Engine running at normal operating temperature

INSPECTION PROCEDURE

CHECK MEMORY FUNCTION
1. 1. Start the engine.
  2. Operate the temperature control switch (driver side) and raise the temperature setting to 89°F or 90°F (32°C).
  3. Press the OFF switch.
  4. Ignition switch OFF.
  5. Ignition switch ON.
  6. Press the AUTO switch.
  7. Check that the temperature setting, before placing the ignition switch OFF, is stored.
Is the inspection result normal?
YES >>
GO TO 2.
NO >>
Check power and ground circuits for A/C auto amp. Refer to Diagnosis Procedure.
CHECK BLOWER MOTOR SPEED
1. 1. Operate the fan control dial. Check that the fan speed changes.
  2. Check the operation for all fan speeds.
Is the inspection result normal?
YES >>
GO TO 3.
NO >>
Check blower motor system. Refer to Diagnosis Procedure.
CHECK DISCHARGE AIR (MODE SWITCH AND DEF SWITCH)
1. 1. Press the MODE switch and the DEF switch.
  2. Check that the air outlets change according to each indicated air outlet by placing a hand in front of the outlets. Refer to System Description.
  Note:
  Confirm that the A/C compressor clutch is engaged (sound or visual inspection) and intake door position is at FRE () (REC position is not selected) when the D/F () or DEF () is selected.
Is the inspection result normal?
YES >>
GO TO 4.
NO >>
Check mode door system. Refer to Diagnosis Procedure.
CHECK INTAKE AIR
1. 1. Press REC () switch one time. REC indicator should illuminate.
  2. Listen to the sound of the air coming out of the vent.
  3. Press REC () switch one more time. REC indicator should go off.
  4. There should be an audible change to the sound of the air flowing out of the vent.
  Note:
  Confirm that the A/C compressor clutch is engaged (sound or visual inspection) and the FRE () door is open (REC position is not selected) when the D/F () or DEF () is selected.
Is the inspection result normal?
YES >>
GO TO 5.
NO >>
Check intake door system. Refer to Diagnosis Procedure.
CHECK A/C SWITCH
1. 1. Press the A/C switch.
  2. The A/C switch indicator is turned ON.
    
    Confirm that the A/C compressor clutch engages (sound or visual inspection).
Is the inspection result normal?
YES >>
GO TO 6.
NO >>
Check magnet clutch system. Refer to Diagnosis Procedure.
CHECK TEMPERATURE DECREASE
1. 1. Operate the A/C compressor.
  2. Operate the temperature control switch (driver side) and lower the temperature setting to 60°F or 61°F (18°C).
  3. Check that the cool air blows from the outlets.
Is the inspection result normal?
YES >>
GO TO 7.
NO >>
Check for insufficient cooling. Refer to Diagnosis Procedure.
CHECK TEMPERATURE INCREASE
1. 1. Operate the temperature control switch (driver side) and raise the temperature setting to 89°F or 90°F (32°C) after warming up the engine.
  2. Check that the warm air blows from the outlets.
Is the inspection result normal?
YES >>
GO TO 8.
NO >>
Check for insufficient heating. Refer to Diagnosis Procedure.
CHECK DUAL MODE FUNCTION
1. 1. Press the DUAL mode switch, and then check that “DUAL” is shown on the display.
  2. Operate the temperature control switch (driver side). Check that the discharge air temperature (driver side) changes.
  3. Operate the temperature control switch (passenger side). Check that the discharge air temperature (passenger side) changes.
  4. Press the DUAL mode switch, and then check that the temperature setting (driver/passenger) is unified to the driver side temperature setting.
Is the inspection result normal?
YES >>
GO TO 9.
NO >>
Refer to Diagnosis Chart By Symptom and perform the appropriate diagnosis.
CHECK AUTO MODE
1. 1. Press the AUTO switch, and then check that “AUTO” is shown on the display.
  2. Operate the temperature control switch (driver side). Check that the fan speed, outlet air or intake air changes. The discharge air temperature or fan speed varies depending on the ambient temperature, in-Nissan Sentra vehicle temperature, and temperature setting.
Is the inspection result normal?
YES >>
Inspection End.
NO >>
Refer to Diagnosis Chart By Symptom and perform the appropriate diagnosis.

System Setting

Temperature Setting Trimmer

Temperature Setting Trimmer

Description

If the temperature felt by the customer is different than the airflow temperature controlled by the temperature setting, the auto amplifier control temperature can be adjusted to compensate for the temperature setting.

How to set

CONSULT

Select “TEMP SET CORRECT” in “Work support” mode of “HVAC”.

Work support items	Display (°F)	Display (°C)
TEMP SET CORRECT	6	3.0
	5	2.5
	4	2.0
	3	1.5
	2	1.0
	1	0.5
	0 (initial status)	0 (initial status)
	−1	−0.5
	−2	−1.0
	−3	−1.5
	−4	−2.0
	−5	−2.5
	−6	−3.0

Note:

When the temperature setting is set to 77°F (25.0°C) and −6°F (−3.0°C), the temperature controlled by auto amp. is 77°F (25.0°C) −6°F (−3.0°C) = 71°F (22.0°C) and the temperature becomes lower than the temperature setting.
When the battery cable is disconnected from the negative terminal or when the battery voltage becomes 10V or less, the setting of the difference between the temperature setting and control temperature may be cancelled.

Inlet Port Memory Function (fre)

Inlet Port Memory Function (FRE)

Description

If the ignition switch is placed to the OFF position while the FRE () switch is set to ON (fresh air intake), “Perform the memory” or “Do not perform the memory” of the FRE () switch ON (fresh air intake) condition can be selected.
If “Perform the memory” was set, the FRE () switch will be ON (fresh air intake) when placing the ignition switch to the ON position again.
If “Do not perform the memory” was set, the air inlets will be controlled automatically when placing the ignition switch to the ON position again.

How to set

CONSULT

Select “FRE MEMORY SET” in “Work support” mode of “HVAC”.

Work support items	Display	Setting
FRE MEMORY SET	WITHOUT	Perform the memory of manual FRE
FRE MEMORY SET	WITH (initial status)	Do not perform the memory of manual FRE (auto control)

Note:

When the battery cable is disconnected from the negative terminal or when the battery voltage becomes 10V or less, the setting of the FRE switch memory function may be cancelled.

Inlet Port Memory Function (rec)

Inlet Port Memory Function (REC)

Description

If the ignition switch is placed to the OFF position while the REC () switch is set to ON (recirculation), “Perform the memory” or “Do not perform the memory” of the REC () switch ON (recirculation) condition can be selected.
If “Perform the memory” was set, the REC () switch will be ON (recirculation) when placing the ignition switch to the ON position again.
If “Do not perform the memory” was set, the air inlets will be controlled automatically when placing the ignition switch to the ON position again.

How to set

CONSULT

Select “REC MEMORY SET” in “Work support” mode of “HVAC”.

Work support items	Display	Setting
REC MEMORY SET	WITHOUT (initial status)	Perform the memory of manual REC
REC MEMORY SET	WITH	Do not perform the memory of manual REC (auto control)

Note:

When the battery cable is disconnected from the negative terminal or when the battery voltage becomes 10V or less, the setting of the REC switch memory function may be cancelled.

Target Evaporator Temp Upper Limit

Target Evaporator Temp Upper Limit

DESCRIPTION

Set the target evaporator temperature upper limit.

HOW TO SET

CONSULT

Select “TARGET EVAPORATOR TEMP UPPER LIMIT SETTING” in “Work support” mode of “HVAC”.

Work support items	Display
TARGET EVAPORATOR TEMP UPPER LIMIT SETTING	Initial Setting
	Low
	Middle
	High

Foot Position Setting Trimmer

Foot Position Setting Trimmer

DESCRIPTION

In FOOT mode, the air blowing to DEF can change ON/OFF.

HOW TO SET

CONSULT

Select “BLOW SET” in “Work support” mode of “HVAC”.

Work support items	Display	Defroster door position
Work support items	Display	Auto control	Manual control
BLOW SET	Mode1 (initial status)	OPEN	CLOSE
	Mode2	OPEN	OPEN
	Mode3	CLOSE	OPEN
	Mode4	CLOSE	CLOSE

Note:

When the battery cable is disconnected from the negative terminal or when the battery voltage becomes 10V or less, the setting of the discharge air mix ratio in FOOT mode may be cancelled.

Door Motor Starting Position Reset

Description

Description

Reset signal is transmitted from A/C auto amp. to air mix door motor and mode door motor. Starting position reset can be performed.
Note:
During reset, DEF switch indicator blinks.
When air mix door motor or mode door motor is removed and installed, always perform door motor starting position reset.

Work Procedure

Work Procedure

PERFORM DOOR MOTOR STARTING POSITION RESET
1. CONSULT
  1. Ignition switch ON.
  2. Select “Door Motor Starting Position Reset” in “Active Test” mode of “HVAC”.
  3. Select “Start” and wait a few seconds.
  4. Make sure the “COMPLETED” is displayed on CONSULT screen.
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Inspection End.

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