1999 NISSAN PRIMERA Control

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

FAN CONTROL SWITCH
Manual control of the blower speed. Four speeds are available for manual control (as shown on the display
screen):
low
I, medium lowII, medium highIII, highIIII
MODE CONTROL KNOB
This knob controls outlet air flow.
In ªDEFº (
) mode, the intake door is set to ªFRESHº, and the A/C on.
AUTO SWITCH
The air mix door, and blower speed are automatically controlled so that the in-vehicle temperature will reach,
and be maintained at the set temperature selected by the operator.
TEMPERATURE CONTROL SWITCH (POTENTIO TEMPERATURE CONTROL)
Increases or decreases the set temperature.
RECIRCULATION (REC) SWITCH
OFF position: Outside air is drawn into the passenger compartment.
ON position: Interior air is recirculated inside the vehicle.
RECIRC is canceled when DEF mode is selected.
AIR CONDITIONING SWITCH
The air conditioner switch controls the A/C system. When the switch is depressed with the fan ON, the
compressor will turn ON. The display screen indicates ªA/Cº.
A/C switch will turn on when DEF mode is selected.
The air conditioner cooling function operates only when the engine is running.
DESCRIPTIONAUTO
Control Operation (Cont'd)
HA-22