3315498 - Introduction - AIR CONDITIONING CASING AND COMPONENTS

CLIMATE CONTROL WITH AUTOMATIC TEMPERATURE CONTROL

Presentation

The climate control system is the following type:

  • automatic temperature - ventilation - distribution control
  • with recirculation
  • with direction of the flows.
The user can select the desired air flow and temperature.A special control unit manages the operation of the system.

The control unit implements the thermaladjustment according to the signals received from the:

  • outside air temperature sensor
  • inside air temperature sensor
  • vent outlet treated air temperature sensors
  • solar radiation sensor

According to the signals received, operates the following are operated to reach and maintain a comfortable temperature inside the passenger compartment:

  • mixture actuator
  • recirculation actuator
  • distribution actuator
  • electric fan
  • compressor.
In addition, the control unit operates the heated rear windscreen via the integrated services control unit.

The climate control system basically consists of:

  • air intake unit
  • air filter unit
  • electric fan
  • air conditioning unit
  • mixture unit
  • heater unit
  • distribution unit.
1, Air conditioning compressor 2, Air conditioning condenser 3, Drier filter 4, Expansion valve 5, Evaporator unit 6, 4 stage pressure switch 7, Outside air temperature sensor 8, Solar radiation sensor Air intake unit

The air intake unit makes it possible to:

  • let outside air enter the passenger compartment
  • circulate the air inside the passenger compartment.
An actuator, controlled by the control unit, moves the air intake flap into the two different positions.Air filter unitThis consists of a filter which makes it possible to reduce pollution, pollen and some unpleasant odours.Ventilation unitThis consists of a brushles motor which, depending on the voltage applied to the inlet circuit, regulates the speed of the fan and consequently the air flow rate.Air conditioning unit

It consists of:

  • a compressor
  • an expansion valve
  • an evaporator
  • a condenser
  • a drier filter
  • pipes
  • a 4 stage pressure switch
It makes it possible to cool and/or dehumidify the air introduced into the passenger compartment.Mixture unitIt consists of special flaps and ducts which allow the temperature of the air introduced into the passenger compartment to be controlled.Heater unitIt consists of a radiator supplied by the engine coolant which allows the air introduced into the passenger compartment to be heated.Distribution unitIt consists of a series of flaps and ducts with special vents.It allows the air to be distributed to the various parts of the passenger compartment.

Climate control controls

The user interface, integrated in the ICS system, for the climate control system consists of:

  • controls
  • a monitor with a colour display.
The climate control system controls appear on a single page by pressing the "CLIMA" button.

The following are displayed:

  • internal temperature set (in ° C or in °F)
  • fan setting symbol
  • air distribution symbol (windscreen, centre of vehicle, floor)
  • defrost symbol (defrost ventilation activated/deactivated)
  • recirculation symbol (recirculaion activated/deactivated)
  • "MANUAL" or "AUTO" or "FULL AUTO" warning for modification of manual setting or automatic operation.

Operating logics

Starting transitionThis logic is designed so as not to create problems for the user (cold air jets and/or demisting of the front window) in certain temperature conditions during starting.

During the starting transition with "FULL AUTO" operation, the following functions are implemented:

  • initial air distribution to "FLOOR" and then "DEF"
  • air mixture flap completely open (maximum heat)
  • recirculation air flap in "dynamic air" position
  • compressor enabled
  • increasing variation in the air flow rate until a level calculated by the control unit is reached.

This logic is interrupted by possible requests for:

  • maximum cold (LO)
  • maximum heat (HI)
  • defrost (FRONT).
Maximum heat request (hi)This is activated by setting a temperature value above 28° C corresponding to "HI".

To satisfy this requirement the system exits from the automatic control of the thermal adjustment ((FULL AIUTO) and modifies the system functions as described below:

  • air mixture flap completely open (maximum heat).
  • automatic air distribution: distribution flaps in "FLOOR" position
  • manual air distribution: position of distribution flaps dependent on the preselected setting.
  • automatic ventilation: maximum permissible flow rate
  • manual ventilation: with flow rate corresponding to that preselected.
The interruption of the ventilation function takes place when the key is turned to the OFF position, or when the "OFF" button is operated or when the "defrost" button is operated.Maximum cold request (lo)This is activated by setting a temperature value below 16° C corresponding to "LO".

To satisfy this requirement the system exits the automatic thermal adjustment control (FULL AUTO) and modifies the system functions as follows:

  • air mixture flap completely closed (maximum cold)
  • automatic air distribution: distribution flaps in "VENT" position
  • manual air distribution: distribution flaps position dependent on the preselected setting.
  • automatic ventilation: maximum permissible flow rate
  • manual ventilation: flow rate corresponding to that preselected.
  • recirculation: air intake flap forced into recirculation position.
The interruption of the recirculation function occurs if the ignition is turned to the OFF position or if the "OFF" button is operated or if the "defrost" button is operated.Defrost requestIt is activted using the "FRONT" button and manages the air flow rate depending on the temperature of the treated air coming out of the vents designed to demist the windows inside the passenger compartment.

The management of the defrost involves the system functions as described below:

  • compressor enabled.
  • air distribution initially to "FLOOR" and then "DEF".
  • air mixture flap completely open (maximum heat)
  • Ventilation: the management of the automatic air flow rate depends on the temperature of the treated air.
  • recirculation: the air intake flap is forced into the dynamic position.
  • heated rear windscreen management: the heated rear windscreen is activated by the integrated services electronic control unit, in accordance with an operating logic (see DESCRIPTIONS AND OPERATION: Integrated multiservices control unit - 5505).
This function is interrupted by operating the "OFF" button.
The defrost function has priority over the following request:
- maximum cold (LO)- maximum heat (HI)."full-auto" operation requestThe completely automatic thermal adjustment control is implemented by pressing the AUTO button with the temperature setting between 16° C and 28° C."auto" operation request

The partial thermo-dynamically controlled thermal adjustment is implemented by:

  • pressing the AUTO button with the temperature setting between 16° C and 28° C and
  • modifying one of the following parameters: air flow rate, air distribution and recirculation.

This function is interrupted by operating:

  • the "OFF" button
  • by the maximum heat request (HI)
  • by the maximum cold request (LO)
Compressor engagement

The compressor is enabled with the:

  • evaporator temperature close to 5 ° C
  • defrost function selected
  • recirculation function switched off and outside temperature above 5 ° C.

The compressor is disabled with the:

  • recirculation function engaged and the outside temperature below - 5 ° C
  • recirculation function switched off and the outside temperature 3 ° C.
The compressor can also be switched off by operating the multi-stage pressure switch controlling the circuit or by the injection/ignition control unit (see DESCRIPTIONS AND OPERATION: Injection/ignition system - 1056).

System components

Duct/distributor unit

This consists of three modules which inside contain:

  • the electric fan
  • the evaporator
  • the heater radiator
  • Upper mixed air temperature sensor
  • Lower mixed air temperature sensor
All the flaps are operated by special actuators controlled by the control unit.
1, Electric fan 2, Evaporator 3, Heater radiator 4, Upper mixed air temperature sensor 5, Lower mixed air temperature sensor 6, Outside/recirculation air flap actuator 7, Air distribution flaps actuator 8, Mixed air flaps actuator 9, Combined filter element Air distribution
1, Intake/recirculation air flap 2, Electric fan 3, Evaporator 4, Heater radiator 5, Mixed air flap 6, Air distribution flap A, Recirculation air flow B, Outside air flow C, Windscreen/side windows air flow D, Centre and side vents air flow E, Lower and rear vents air flow Electric fanThe ventilation unit is made up of a brushless type direct current motor which, by means of the voltage applied to the intake circuit, makes it possible to control the fan speed and consequently the air flow rate using a PWM signal.

The lack of brushes and commutator allows:

  • a reduction in inertia and wear
  • the lack of electrical and mechanical leaks
  • improved reliability, power and acceleration for the same torque.
The absence of the commutator eliminates problems of discharges between the terminals; the function of the commutator is carried out by an external electronic switching circuit which produces the current in the induction winding.There are less vibrations with this type of motor and lower consumption than compared with traditional linear control motors.
1, Electronic components inserted in an impermeable system 2, Card for electronics and connections 3, Support for motor and semiconductor heat dissipator 4, Centrifugal fan with high output and low noise 5, Motor cooling fan 6, Rotors with ferrite magnets 7, Laminated stator and winding Combined filter element

The air introduced into the passenger compartment from the outside passes through a combined filter, i.e. consisting of two layers:

  • the first "particle" layer has the task of trapping the small particles of fine dust and pollen
  • the second "active charcoal" layer is designed to trap certain pollutant elements (odours) in the atmosphere.
Heater radiatorThis is a heat exchanger connected to the engine cooling circuit by means of special pipes: - one draws in hot water from the engine and allows the heating of the air introduced into the passenger compartment- one allows the return of the coolant to the engine.
Outside/recirculation air flap actuatorThis activates the rotation of the outside/recirculation air flap in the two extreme position "dynamic air" and "recirculation" without an intermediate position, through the command received from the electronic control unit.A motor controls the rotary movement of a drive pin which acts directly on the flap.It receives a 12 V supply and if the polarity is reversed, it is possible to rotate it in a clockwise or an anti-clockwise direction.The actuator is not fitted with a feedback potentiometer and therefore it is controlled by the control unit by checking the current absorption.
Air distribution flaps actuatorThis operates the rotation of the two air distribution flaps according to the command from the electronic control unit.A motor controls the rotary movement of a drive pin which acts directly on the flaps if supplied with a variable duty-cycle signal.A potentiometer detects the effective position and acts with feedback to the control unit checking the complete travel between the extreme positions.
Mixed air flaps actuatorIt operates the rotation of the two mixed air flaps according to the command from the electronic control unit.A motor controls the rotary movement of a drive pin which acts directly on the mixture flaps if supplied with a duty-cycle signal.A potentiometer detects the effective position and acts with feedback to the control unit checking the
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Air conditioner compressorA Denso 6Ca17 variable capacity (6 cylinder) compressor is fitted on this version.

It consists of two main sections:

  • the compressor casing (1)
  • the clutch assembly (2)
A, Clutch assembly fixing bolt B, Hub C, Pulley retaining circlip D, Pulley E, Solenoid pulley circlip F, Solenoid G, Scraper rings for adjusting clutch clearance H, Earth connection cable I, Solenoid supply cable The flow rate is adjusted by varying the piston stroke according to the angle of the oscillating disc.The angle of the oscillating disc is controlled by the regulating valve, which varies the internal pressure (Pc) of the compressor on the basis of the inlet pressure (Ps).The variation of the internal pressure determines the inclination angle of the drive disc and varies the piston stroke and consequently the capacity by a minimum value of 11% up to a maximum value of 100%.
With the adoptin of the Denso 6CA 17 compressor, the climate control system is not fitted with a frost sensor because this function is carried out by the compressor.
1, Seal 2, Drive disc support 3, Drive disc 4, Oscillating disc (connecting rod holder) 5, Piston 6, Secondary regulating valve 7, Main regulating valve 8, Compressor internal chamber 9, Connecting rod When the coolant fluid cools down, this causes the formation of ice inside the evaporator.The consequent reduction in the section of the pipe hinders the passage of the gas and causes a reduction in the inlet pressure Ps.The force of the lower spring (2) in the main regulating valve (1) exceeds the forces exerted by the inlet pressure and the upper valve (3), opening the valve.There is consequently a flow of gas from the compression chamber inside the compressor.The increased internal pressure Pc overcomes the inlet pressure Ps and moves the lower piston (4) to the right (increase in the inclination angle "a" of the drive disc (5)).As a result, the piston stroke decreases and operation is at partial capacity.
1, Main regulating valve 2, Lower spring 3, Upper spring 4, Lower piston 5, Drive disc When the formation of ice inside the evaporator is reduced, the inlet pressure Ps increases and pushes the diaphragm (2) downwards; the valve (1) closes.The closure of the valve causes a reduction in the compressor internal pressure Pc.Under these circumstances, the inlet pressure Ps overcomes the resistance of the pressure inside the compressor Pc and moves the lower piston (3) towards the left (the inclination angle "a" of the drive disc (4) is reduced).As a result, the piston stroke increases and "operation is at maximum capacity".
1, Main regulating valve 2, Diaphragm 3, Lower piston 4, Drive disc Multi-stage pressure switchThis is a 4 stage pressure switch which controls the safe and correct operation of the system.

The 4 pressure stages make it possible to switch on/off the:

  • air conditioning compressor
  • cooling fan.
1st stage (about 2.5 bar): minimum pressure allowing the compressor to be switched on2nd stage (about 15 bar): pressure which requires the first fan speed to be switched on3rd stage (about 20 bar): pressure which requires the second fan speed to be switched on4th stage (about 28 bar): maximum pressure which deactivates the compressor.
Expansion valveIt is fitted on the evaporator inlet and outlet pipes and regualtes the flow and expansion of the coolant fluid causing it to change from the liquid stage to the gaseous state before entering the evaporator.A sensitive bulb automatically regulates the size of the passage of the coolant fluid inside the expansion valve.According to the temperature of the coolant fluid, it regulates the size of the opening acting on a spring which moves a shutter and determines the extent of the expansion.The increase in temperature at the evaporator outlet, measured by the sensitive bulb, causes the opening of the valve with a consequent increase in the flow rate of the fluid to the evaporator.Conversely, at low temperatures, the flow rate is decreased.
The valve adjustment screw is calibrated in production and should not be tampered with: this would involve a decrease in the efficiency of the system.
1, Sensitive bulb 2, Passage 3, Spring 4, Shutter 5, Adjustment screw EvaporatorThis is a heat exchanger fitted inside the duct/distributor unit.It consists of an aluminium structure with fins which increase the heat exchange surface.The expansion takes place inside the evaporator with the consequent evaporation of the coolant fluid which causes a rapid decrease in the temperature.The air, dynamic or recirculation, which passes through the evaporator is therefore cooled and dehumidified.The humidity which condenses on the evaporator fins is collected and discharged outside the vehicle through a special pipe.The evaporator is chemically treated to be resistant to corrosion.