NISSAN PRIMERA 1999 Electronic Repair Manual

Refrigeration Cycle
REFRIGERANT FLOW
The refrigerant flow is in the standard pattern. Refrigerant flows through the compressor, condenser, liquid
tank, evaporator, and back to the compressor.
The refrigerant evaporation through the evaporator coil is controlled by an externally equalized expansion
valve, located inside the evaporator case.
FREEZE PROTECTION
Variable displacement (CSV613)
Under normal operating conditions, when the A/C is switched on, the compressor runs continuously, and the
evaporator pressure, therefore temperature, is controlled by the CSV613 variable displacement compressor
to prevent freeze up.
Vane rotary (CR-14)
The compressor cycles on and off to maintain the evaporator temperature within a specified range. When
the evaporator coil temperature falls below a specified point, the thermo control amplifier interrupts the
compressor operation. When the evaporator coil temperature rises above the specification, the thermo con-
trol amplifier allows compressor operation.
REFRIGERANT SYSTEM PROTECTION
Dual-pressure switch (System with CR-14 compressor)
The refrigerant system is protected against excessively high or low pressure by the dual-pressure switch,
located on the liquid tank. If the system pressure rises above, or falls below the specifications, the dual-
pressure switch opens to interrupt the compressor operation.
Pressure sensor (System with CSV613 compressor)
The pressure sensor is located on the liquid tank. It converts the system pressure into a voltage value witch
is then input into ECM.
If the system pressure rises above, or falls below the specifications, ECM interrupt the compressor opera-
tion.
Fusible plug
Open at temperatures above 105ÉC (221ÉF), thereby discharging refrigerant to the atmosphere. If this plug
is melted and opened, check the refrigerant line and replace liquid tank.
Pressure relief valve (CSV613 compressor)
The refrigerant system is also protected by a pressure relief valve, located in the rear head of the compres-
sor. When the pressure of refrigerant in the system increases to an abnormal level [more than 3,727 kPa
(38 kg/cm
2, 540 psi)], the release port on the pressure relief valve automatically opens and releases refrig-
erant into the atmosphere.
DESCRIPTION
HA-12

RHA896FA Pressure relief valve (CSV613 only)
Outside airCompressor
Condenser
Liquid tank
Dual-pressure switch/ pressure sensorExpansion valveBlower motor EvaporatorHigh-pressure
gas
High-pressure
liquidLow-pressure
liquid
Low-pressure
gas
DESCRIPTION
Refrigeration Cycle (Cont'd)
HA-13

CSV613 Variable Displacement Compressor
GENERAL INFORMATION
1. The CSV613 compressor differs from previous units. The vent temperatures of the CSV613 compress
or do not drop too far below 5ÉC (41ÉF) when:
levaporator intake air temperature is less than 20ÉC (68ÉF)
lengine is running at speeds less than 1,500 rpm.
This is because the CSV613 compressor provides a means of ªcapacityº control.
2. The CSV613 compressor provides refrigerant control under varying conditions. During cold winters, it
may not produce high refrigerant pressure discharge (compared to previous units) when used with air
conditioning systems.
3. A ªclankingº sound may occasionally be heard during refrigerant charge. The sound indicates that the
tilt angle of the swash plate has changed and is not a problem.
4. For air conditioning systems with the CSV613 compressor, the clutch remains engaged unless: the sys-
tem main switch, fan switch or ignition switch is turned OFF. When ambient (outside) temperatures are
low or when the amount of refrigerant is insufficient, the clutch is disengaged to protect the compressor.
5. A constant range of suction pressure is maintained when engine speed is greater than a certain value.
It normally ranges from 147 to 177 kPa (1.47 to 1.77 bar, 1.5 to 1.8 kg/cm
2, 21 to 26 psi) under vary-
ing conditions.
In previous compressors, however, suction pressure was reduced with increases in engine speed.
DESCRIPTION
HA-14

DESCRIPTION
General
The variable compressor is basically a swash plate type that changes piston stroke in response to the
required cooling capacity.
The tilt of the swash plate allows the piston's stroke to change so that refrigerant discharge can be continu-
ously changed from 6 to 125 cm
3(0.366 to 7.63 cu in).
KHA103 ShaftSealJournal pin
Swash plate
Rear Head
Discharge
valve plate
Control valve
Cylinder
Piston Oil drain bolt
Swash plate
tilting angle
changesLong stroke
(Large amount of refrigerant discharge)
Short stroke
(Small amount of refrigerant
discharge)
Drive lug
Journal pin
Discharge
controlDischarge
capacity
cm
3(cu in)/rev.Pistonstroke
length
mm (in)
Minimum 6 (0.366) 1.2(0.039)
Maximum 125 (7.63) 25.9 (1.02)
DESCRIPTION
CSV613 Variable Displacement Compressor
(Cont'd)
HA-15

Operation
1. Operation control valve
Operation control valve is located in the suction port (low-pressure) side, and opens or closes in response
to changes in refrigerant suction pressure.
Operation of the valve controls the internal pressure of the crankcase.
The angle of the swash plate is controlled between the crankcase's internal pressure and the piston cyl-
inder pressure.
2. Maximum cooling
Refrigerant pressure on the low-pressure side increases with an increase in heat loads.
When this occurs, the control valve's bellows compress to open the low-pressure side valve and close
the high-pressure side valve.
This causes the following pressure changes:
lthe crankcase's internal pressure to equal the pressure on the low-pressure side;
lthe cylinder's internal pressure to be greater than the crankcase's internal pressure.
Under this condition, the swash plate is set to the maximum stroke position.
RHA473C Discharge port
Suction portCrankcase
Low-pressure valve: Open
Bellows
Valve position for lowering
crankcase pressureSpring pressureCylinder pres-
sure
Crankcase pres-
sure
Forces needed to increase stroke
DESCRIPTION
CSV613 Variable Displacement Compressor
(Cont'd)
HA-16

3. Capacity control
lRefrigerant pressure on suction side is low during high speed driving or when ambient or interior tem-
perature is low.
lThe bellows expands when refrigerant pressure on the suction pressure side drops below approximately
177 kPa (1.77 bar, 1.8 kg/cm2, 26 psi).
Since suction pressure is low, it makes the suction port close and the discharge port open. Thus, crank-
case pressure becomes high as high pressure enters the crankcase.
lThe force acts around the journal pin near the swash plate, and is generated by the pressure difference
before and behind the piston.
The drive lug and journal pin are located where the piston generates the highest pressure. Piston pres-
sure is between suction pressure Ps and discharge pressure Pd, which is near suction pressure Ps. If
crankcase pressure Pc rises due to capacity control, the force around the journal pin makes the swash
plate angle decrease and also the piston stroke decrease. In other words, crankcase pressure increase
triggers pressure difference between the piston and the crankcase. The pressure difference changes the
angle of the swash plate.
RHA474C Discharge port
Suction portCrankcase Low-pressure valve: Open
Valve position for lowering
crankcase pressureSpring pressureCylinder pres-
sure
Crankcase pres-
sure
Forces needed to increase stroke
DESCRIPTION
CSV613 Variable Displacement Compressor
(Cont'd)
HA-17

Component Layout
KHA104 Side defroster nozzle
Defroster nozzle
Side defroster nozzle
Side ventilator duct Center ventilator duct
Intake unit
Control assembly
(Heater) Cooler unit
Fresh vent
control leverHeater unitSide ventilator duct
For Scandinavian models only:
Rear heater duct
(Whenremoving rear heater
duct, it is necessary
to remove frontseats.)
SEC. 270×271×272×273
Control assembly
(Air conditioner)
DESCRIPTION
HA-18

Control Operation
FAN CONTROL KNOB
This knob turns the fan ON and OFF, and controls fan speed.
MODE CONTROL KNOB
This knob controls the outlet air flow.
TEMPERATURE CONTROL KNOB
This knob allows adjustment of the temperature of the outlet air.
RECIRCULATION (REC) SWITCH
OFF position:
Outside air is drawn into the passenger compartment.
ON position:
Interior air is recirculated inside the vehicle.
The indicator lamp will also light.
Air Flow
FRESH VENT SYSTEM
This system is controlled by means of the fresh air vent lever which is mechanically linked to the fresh vent
door by the control cable.
Fresh vent air always comes from the center vent in any mode when the fresh air vent lever is set at the
blue dot position.
KHA105 Fan
control knobTemperature
control knobMode
control knobMode
control knobTemperature
control knobFan
control knob
Rear defroster
switchRecirculation
switch
.Rear defroster
switch Recirculation
switch LHD modelsRHD models
KHA064 Fresh air vent
control lever
Set at blue dot positionTo defroster
Heater core
Evaporator
Outside air
To floor To floor
Fresh air vent con-
trol cable
DESCRIPTIONHEATER
HA-19

Introduction
The automatic temperature control (ATC) system provides automatic regulation of the discharged air tem-
perature and the discharged air volume (Blower speed).
The air outlet door, intake door and compressor magnet clutch are controlled by the manual operation of
each switch.
Features
Air mix door control (Automatic temperature control)
The air mix door is automatically controlled so that in-vehicle temperature will reach, and be maintained at
the operator selected ªset temperatureº. For a given set temperature, the air mix door position will depend
on: Ambient temperature, in-vehicle temperature, amount of sunload, set temperature and A/C switch sig-
nals.
Fan speed control
When the fan control switch is in the Auto position, the blower speed is automatically controlled, depending
on: Ambient temperature, in-vehicle temperature, amount of sunload, set temperature, and A/C switch sig-
nals. It is also controlled by the manual operation of the fan control switch.
Starting fan speed control
When engine coolant temperature is low, the air outlet door position is detected by the A/C control panel
and if this is set in B/L, FOOT or FOOT/DEF blower speed is controlled to prevent a large amount of cold
air from being discharged into the floor area.
Outlet door control
This can be selected by operation of the mode control knob.
Intake door control
This can be selected by changing the REC switch position.
Compressor magnet clutch control
System with CR-14 compressor
When the A/C switch is ON, the thermistor detects evaporator temperature. The thermo control amplifier
controls clutch ON/OFF operation depending on the evaporator temperature.
System with CSV613 compressor
Under normal operating conditions, when the A/C is switched on, the compressor runs continuously, and the
evaporator pressure, and therefore temperature, is controlled by the CSV613 variable displacement com-
pressor to prevent freeze up.
DESCRIPTIONAUTO
HA-20

Control Operation
The control system consist of a) input sensors and switches, b) the automatic amplifier (microcomputer), and
c) outputs.
The relationship of these components is shown in the diagram below:
KHA111 Control unit
lSet temperature Control
(Potentio temperature control)
Ambient sensor
In-vehicle sensor
Sunload sensor
Thermal transmitterAutomatic
amplifier
(Micro- com-
puter)Air mix door motor
PBR
(Potentio Balance Resis-
tor)built-into air mix door
motor
FanAir mix door
Blower motor
KHA112 Auto air conditioner
Air conditioner switchMode control knob
Auto switch
Fan control
Recirculation
switchRear window
defogger switchTemperature control
switch (PTC)
DESCRIPTIONAUTO
HA-21