SECTION 82                           AIR CONDITIONING                                              STAG

 General

 This system is designed to provide either heated air to warm the interior as available in a conventional heater-equipped vehicle or cooled, dried, and cleaned air for increased comfort in hot climates.

 Controls

 Lever 'A'

 The system draws either fresh air at ambient temperature through the bulkhead aperture or recirculated air from the vehicle interior.  The choice is a driver function by selection at lever 'A'.  To obtain maximum heating and particularly maximum benefit from the cooling system in hot climates select 'RECIRC'.

 Lever 'B'

 Moving lever 'B' to the right of its central 'OFF' position will cause any air flowing from the screen outlets or footwell outlets to be heated.  The position of lever 'B' between 'OFF' and 'HOT' initially directs the degree of heat required.  The interior temperature is continually sensed, and the hot matrix temperature automatically adjusted, to maintain an approximately constant temperature within the vehicle.

Moving lever 'B' to the left of its central 'OFF' position will select the cooling system.  The refrigeration circuit is energized to cool the cold matrix, two blower units are brought into operation and flaps are automatically positioned within the unit to cause the total cold air volume to be split into the vehicle interior from the central facia vent and the two facia louvres.  The position of lever 'B' between 'OFF' and 'COLD' initially directs the degree of cooling required.  The interior temperature is continually sensed, and the cold matrix temperature automatically adjusted, to maintain an approximately constant temperature within the vehicle.

 

Lever 'C'

 

When the cooling system is selected the position of lever 'C' has no relevance.

 

Lever 'C' is effective when heated or ambient air is being delivered.  When selected to 'SCREEN' the total air volume is directed to the screen vents.  Moving the lever down progressively decreases the flow to the screen and increases the flow to the footwells.  A selection to 'CAR' will cause the majority of air to be delivered to the footwells.

Fig. 82.01. Controls.

STAG                                 AIR CONDITIONING                                  SECTION 82

 Blower switch

 Two blower units may be used to increase the fresh air flow when the car is operating in extremes of temperature or at low road speeds.  When the recirculating system is employed the blower units must be used to induce the flow.  To operate, pull the knob to the first position for low speed and fully out for high speed.  It may be noted that selecting the cooling system will automatically bring into

 operation the blower units at low speed.  From this condition high speed may be obtained by pulling the switch knob fully out.

 

Outlets

 Screen outlets

     Heated or ambient air may be used to demist or defrost the windscreen.

 Footwell outlets

Heated or ambient air may be provided to heat or ventilate the vehicle interior.

 Centralfacia vent

         Refrigerated air only may be split into the vehicle interior from this outlet.  It may be noted that unless 'COLD' is selected no flow occurs.

 Facia louvres

     When lever 'B' is selected to 'OFF' or 'HOT' a flow at ambient temperature is available.  The flow direction and volume is adjustable at each facia louvre.  When lever 'B' is selected to 'COLD' a flow of refrigerated air is available.  Again the direction and volume is adjustable at each facia louvre.

 

 Hot water circuit

 The hot water flow is induced by the engine water pump.  Hot water is drawn from the water transfer housing at the rear of the left-hand bank and passes through the water flow valve to the hot matrix.  From the hot matrix outlet the flow is forward between the two banks to enter the water pump housing.  Thus entry is on the section side of the water pump.

 Hot temperature sensing system

 This system comprises three main components.  A vacuum tank exhausted by engine suction; a manually set temperature-sensing air bleed valve; and a diaphragm-operated water flow valve.

 The air bleed valve is located in the control box.  The position of lever 'B' between 'OFF' and 'HOT' determines the initial setting of the valve.  This is achieved by a large cam plate within the control box.  The interior temperature of the car further affects the valve to govern the exact degree of air bleeding.

 The degree of air bleeding directly affects the vacuum above the diaphragm which determines the water flow volume.  The hot matrix temperature is therefore automatically adjusted to maintain an approximately constant temperature within the vehicle.

 

  

Air conditioner unit

 Introduction

The air conditioner unit is positioned on the centre line of the vehicle between the bulkhead and the facia/console panels.  The function of the unit is to receive air, process and deliver it to the outlets as directed by the control positions.

 To comprehend the following system descriptions it should be appreciated that control lever 'A' positions flap 'A' in the air conditioner unit.  Similarly lever 'B'positions the two flaps 'B'-this time by vacuum acttiator-and lever 'C'positions the t o flaps 'C'.

 

Intakes 

The system draws fresh air at ambient temperature through the bulkhead aperture, or recirculated air from the vehicle interior, into the air conditioner unit plenum chamber.  The choice is directed by the cable-controlled flap 'A'.

 Blowers 

Two blower units transfer air from the plenum chamber to the distribution area.

 

Matrixes

 Two separate matrixes are employed.  A hot matrix which may be supplied with hot water from the engine cooling system and a cold matrix which may be cooled by the refrigeration circuit.

 

Hot air

 When hot air is demanded the two flaps 'B' are positioned by an uiienergized vacuum actuator to the closed/hot position.  Air from the distribution area flows down across the hot matrix to the hot distribution area.  The heated air then flows to the screen outlets and the footwell outlet in the proportions directed by the two interconnected cable-controlled flaps 'C'.

 

Cold air

 When cold air is selected the two flaps 'B' are positioned by an energized vacuum actuator to the open/cold position.  Air from the distribution area flows across the cold matrix and the total cold air volume is spilt into the vehicle interior from the central facia vent and the two facia louvres.

 

Cooled, dried, and cleaned air

 The air conditioner unit is capable of supplying cooled, dried, and cleaned air when cold air is selected.  Air of the above description is obtained by passing air across the cold matrix.  Heat is extracted from the air and absorbed by the refrigerant.  Moisture carried in the air condenses on the exterior surfaces of the cold matrix and is removed by draining off into a tray below the matrix.  Dust suspended in the air tends to be retained by the moisture and also collects in the tray.  Twiii drain pipes lead down

from the tray to beneath the vehicle.                                                                                     

 

 

  

Refrigeration circuit

 WARNING:      THE REFRIGERATION CIRCUIT MUST ONLY BE DISTURBED BY A QUALIFIED REFRIGERATION ENGINEER POSSESSING THE REQUIRED SPECIAL SERVICING EQUIPMENT.  FAILURE TO OBSERVE THIS INSTRUCTION MAY RESULT IN SEVERE PERSONAL INJURY. 

Introduction

 The function of the refrigeration circuit is to cool the cold matrix.  The circuit comprises the following main components: 

Hoses are employed to transport the refrigerant between components.

 

Expansion valve and cold inatrix 

Liquid refrigerant at high pressure is delivered to the expansion valve.  A severe pressure drop occurs across the valve and as the refrigerant enters the cold matrix space at a temperature of approximately -6' C. it boils and vaporizes.  As this change of state occurs, a large amount of latent heat is absorbed.  The cold matrix is therefore cooled and heat is extracted from the air flowing across the matrix.

 

Compressor 

The compressor draws the refrigerant from the cold matrix as a cold, low pressure gas.  It is compressed, and therefore heated, and passed on to the condenser as a hot, high pressure gas.

 

Condenser

 The condenser is mounted at the front of the car.  Its function Is to remove heat from the refrigerant and disperse it into the atmosphere.  It is delivered with hot, high pressure gas at a temperature of approximately 55' C. Air flow across the tubes, induced by vehicle movement and assisted by two electric fans, cools the gas causing it to condense into a high pressure liquid.  As this change of state occurs a large amount of latent heat is released.

 

Receiver drier

 The refrigerant, in the form of a high pressure liquid, is then passed through the receiver drier.  This unit filters, removes all moisture, and acts as a reservoir for the liquid.  To prevent icing inside the system, extreme precautions are taken during changing to exclude moisture.  The receiver drier should be considered as a second stage insurance to prevent the serious consequences of ice obstructing the flow.

 

Second cycle

 The refrigerant, in the form of a high pressure liquid, is then delivered to the expansion valve and a second cycle commences.

 

Cold temperature sensing system

 This system is electromechanical.  It consists of a manually set cold matrix thermostat operating a relay to control the refrigeration circuit.

 The cold matrix thermostat is located in the control box.  The position of lever 'B' between 'OFF' and 'COLD' determines the initial setting of the thermostat.  This is achieved by a large cam plate within the control box.  The temperature of the cold matrix is recognized by a vapour charged capillary and this signal further affects the thermostat to govern the exact cut in-cut out of the relay.

 The relay switches an electrical supply to either the heated back-light circuit or the refrigeration circuit.  Energizing the refrigeration circuit engages the electromagnetic clutch of the compressor and brings into operation the two electric condenser fans.

 The electromagnetic clutch is the means of cutting the compressor in and out to achieve on-off control of the refrigeration circuit.  The cold matrix temperature is therefore automatically adjusted to maintain an approximately constant temperature within the vehicle.

  

High pressure cut-out

 

WARNING:      ADJUSTMENT OF THE HIGH PRESSURE CUT-OUT SWITCH MUST ONLY BE UNDERTAKEN BY A QUALIFIED REFRIGERATION ENGINEER POSSESSING THE REQUIRED SPECIAL SERVICING EQUIPMENT.

 This system consists of a permanently set refrigerant pressure switch controlling the refrigeration circuit.

 A Ranco high pressure cut-out switch is located at the left-hand engine valance.  Refrigerant pressure is sensed at the receiver drier and governs the cut in@ut out of the electric switch.  The switch directly controls the electrical supply to the electromagnetic clutch of the compressor.

 The electromagnetic clutch is the means of cutting the compressor in and out to achieve on-off control of the refrigeration circuit.  The refrigerant pressure is therefore automatically adjusted to maintain the correct pressure limits.

 

 

Vacuum actuator

 The two flaps'B' are positioned by vachum actuator to closed/hot or open/cold.  No intermediate positions are used.

 This system comprises three main components.  A vacuum tank exhausted by engine suction; a manually controlled air bleed valve; and a diaphragm-operated actuator.

 The air bleed valve is located in the control box.  Moving lever 'B' to the left of its central 'OFF' position will cause the valve to close.  This is achieved by a large cam plate within the control box.

The air bleeding directly affects the vacuum above the diaphragm which determines the position of the actuator.  The actuator drives a simple rod and lever system to position the two flaps 'B'.

  

Facia louvres 

Air flow to the facia louvres may be considered as a variation on the two main airflow patterns of the air conditioner unit.  These are downward through the hot matrix for hot air and horizontal through the cold matrix for cold air.

 

When lever 'B' is selected to 'OFF' or 'HOT' a flow at ambient temperature is available as follows.  The two flaps 'B' are positioned by an unenergized vacuum actuator to the closed/hot position and the cold matrix is blanked off.  However, a limited flow is permitted from the distribution area over the upper edge of the flap and across the cold matrix to the facia louvres.  It may be noted that in this selection the air is not cooled below ambient.  The flow direction and volume is adjustable at each facia louvre.

 

When lever 'B' is selected to 'COLD' a flow of refrigerated air is available as detailed under 'Air conditioner unit-cold air'.

 

Fig 82.02. Air conditioning unit section

A FRESH RECIRC flap controlled by lever 'A'

 B COLD/OFF/HOT flaps controlled by ]ever 'B'.  The two flaps are positioned by vacuum servo to closed/hot or open/cold.  No intermediate positions are used.

 C SCREEN/CAR flaps controlled by lever 'C'

  1.  Recirculated air inlet

  2.  Fresh air inlet

  3.  Air transfer at each side via two blower units from plenum chamber to distribution are

  4.  Hot matrix

  5.  Plenum chamber water drain

  6.  Footwell outlet

  7.  Screen outlets

  8.  Water and dust drain

  9.  Cold matrix

  10.  Facia louvre outlets

  11. Central facia vent outlet

 

 

 

82.03 Typical Air flows

 

 

 

 

 

Compressor

  1.  Condenser 

  2. Receiver drier 

  3. Expansion valve 

  4. Cold matrix

  5. High pressure Cut Out