Nissan Sentra Service Manual: System description
Refrigeration system
Component part location
- High-pressure service port
- High-pressure pipe
- Expansion valve
- Low-pressure service port
- Low-pressure flexible hose
- Compressor
- Refrigerant pressure sensor
- Condenser and liquid tank assembly
- High-pressure flexible hose
Refrigerant cycle
Refrigerant flow
- Electric compressor
- Pressure relief valve
- Liquid tank
- Refrigerant pressure sensor
- Condenser
- Expansion valve
- Evaporator
- Blower motor
- High-pressure gas
- High-pressure liquid
- Low-pressure liquid
- Low-pressure gas
- Suction port
- Discharge port
- Outside air
Refrigerant Flow
The refrigerant from the compressor flows through the condenser and liquid tank, the evaporator and returns to the compressor. The refrigerant evaporation in the evaporator is controlled by an expansion valve.
Freeze Protection
To prevent the evaporator from freezing up, the evaporator air temperature is monitored by the intake sensor and the voltage signal to the A/C auto amp. makes the A/C relay go OFF and stop the compressor
Refrigerant system protection
Refrigerant pressure sensor
The refrigerant system is protected against excessively high or low pressures by the refrigerant pressure sensor, located on the liquid tank. If the system pressure rises above or falls below the specifications, the refrigerant pressure sensor detects the pressure inside the refrigerant line and sends the voltage signal to the ECM.
The ECM then ceases to supply power to the A/C relay which disengages and stops the compressor when pressure on the high pressure side (as detected by refrigerant pressure sensor) is over approximately 2,746 kPa (28 kg/cm2, 398 psi), or below approximately 120 kPa (1.22 kg/cm2, 17.4 psi).
Pressure Relief Valve
The refrigerant system is also protected by a pressure relief valve, located in the rear head of the compressor.
When the pressure of refrigerant in the system increases to an abnormal level [more than 3,727 kPa (38 kg/ cm2, 540 psi)], the release port on the pressure relief valve automatically opens and releases refrigerant into the atmosphere.
Preparation
Special service tool
The actual shape of the tools may differ from those illustrated here.
HFC-134a (r-134a) service tool and equipmen.T.
Do not mix HFC-134a (R-134a) refrigerant and/or its s ...
Basic inspection
Diagnosis and repair workflow
Workflow
OVERALL SEQUENCE
DETAILED FLOW
1.INTERVIEW CUSTOMER
Interview the customer to obtain as much information as possible about the
conditions and environm ...
Other materials:
Rear air spoiler
Removal and installation
Rear air spoiler
High mounted stop lamp connector
(if equipped)
Trunk lid
Grommet
Nut
Front
Removal
Remove trunk lid finisher. Refer to INT-45, "Removal and Installation".
Disconnect the harness connector from the high mounted stop ...
Squeak and rattle trouble diagnoses
Work Flow
Customer interview
Interview the customer if possible, to determine the conditions that exist
when the noise occurs. Use the diagnostic
worksheet during the interview to document the facts and conditions when the
noise occurs and any
customer's comments; refer to rf-37, "d ...
P0300, P0301, P0302, P0303, P0304 Misfire
DTC Logic
DTC DETECTION LOGIC
When a misfire occurs, engine speed will fluctuate. If the engine speed
fluctuates enough to cause the crankshaft
position (CKP) sensor (POS) signal to vary, ECM can determine that a misfire is
occurring.
Sensor
Input signal to ECM
ECM function
...
