General

Climate Control-IHKA

Air Conditioning is standard on the MINI COOPER and COOPER S. The standard system IHKS is a manually controlled basic air conditioning system. Driver input is required to regulate temperature, air direction and air speed.

Available as an option on both models is the IHKA system. This system is able to function as a totally automatic climate control, affecting outlet temperature, air direction and air speed. The IHKA automatic functions may be overridden giving the driver a more precise manual control than is available with the IHKS system.

Purpose of the System
The purpose of the Climate Control system is to control the temperature and distribution of air supplied to the vehicle interior. The Climate Control system is responsible for the heating or cooling of the air coming into the passenger compartment as well as the heating for the rear window and windshield.

Two systems are available on the MINI:

- IHKS (Standard on MINI COOPER and MINI COOPER S)
- IHKA (Optional on MINI COOPER and MINI COOPER S)


Not connected to K-Bus, No diagnostic capabilities


Connected Directly to K-Bus, Fully diagnosable

System Components
Both systems (IHKS and IHKA) consist of a refrigerant system, a heater system and a control system. The refrigerant system is the same on both, the heater assembly and control systems are different.

Refrigerant System (IHKS and IHKA)
The Refrigerant System transfers heat from the vehicle interior to the outside atmosphere providing the heater assembly with dehumidified cool air. The system is a sealed, closed loop, filled with a charge weight (350 gms) of R134a refrigerant as the heat transfer medium. Oil is added to the refrigerant to lubricate the internal components of the compressor.

The refrigerant system consists of the following components:

- R134a Refrigerant and Lubricant
- Compressor
- Condenser
- Receiver/Drier
- Evaporator
- Expansion Valve
- Pressure Transducer
- Evaporator Temperature Sensor
- Refrigerant Lines





R134a Refrigerant
An air conditioning system uses refrigerant to absorb heat from the air that passes through the evaporator. Refrigerants are special materials that are vapors at room temperature and liquids at much lower temperatures. Automotive refrigerants boil at -16° F to -22° F (-27° C to -30° C). Refrigerants are also able to contain and transport a large amount of heat, efficiently, and can be evaporated and condensed over and over without being damaged. In the air conditioning system, liquid refrigerant under high pressure flows through a small hole into the evaporator, where the pressure is then greatly reduced. When the pressure drops, the refrigerant boils and changes from a liquid to a vapor. As it changes its state, it absorbs a large amount of heat.

As the air passing through the evaporator gives up some of its heat, it becomes colder; it can then be blown into the passenger compartment, to cool it. Once the refrigerant has absorbed heat from the air, it is returned to the compressor. The A/C system removes the excess heat from the refrigerant as the refrigerant passes through the condenser.


Compressor
The compressor in an automotive A/C system serves two important functions:

- It creates a low-pressure zone at the compressor inlet, to draw refrigerant vapor from the evaporator.
- It compresses the low-pressure refrigerant vapor into a high-pressure vapor and sends it toward the condenser.


The compressor is a swash plate unit with variable displacement, bolted to an engine bracket, driven by an electromagnetic clutch.

By matching refrigerant flow to the thermal load of the evaporator, the variable compressor maintains a relatively constant evaporator outlet temperature of approximately 3° to 4° C (37° to 39° F).

Condenser
The condenser with integrated receiver/drier is installed in front of the radiator. The receiver/drier is a replaceable unit, located in a threaded housing at the lower end and retained by a plastic bracket at the top.
The condenser transfers heat from the refrigerant to the surrounding air to convert the vapor from the compressor into a liquid.

Receiver/Drier
A receiver/drier integrated in the condenser assembly removes moisture and solid impurities from the refrigerant, and provides a reservoir of liquid refrigerant to accommodate flow changes at the evaporator.

Evaporator
The evaporator is located in the heater assembly and uses an encapsulated sensor to measure the temperature of the air coming off the evaporator. The evaporator is installed in the heater assembly after the blower and absorbs heat from the exterior or re-circulated inlet air. Low pressure, low temperature refrigerant changes from liquid to vapor in the evaporator, absorbing large quantities of heat as it changes state.

Expansion Valve
The expansion valve meters the flow of refrigerant into the evaporator to match the refrigerant flow with the heat of the air passing through the evaporator.

Pressure Transducer



The Pressure Transducer is fitted into the high-pressure line between the condenser and the expansion valve, on the driver's side rear of the engine compartment, under the battery. The pressure transducer signals EMS2000 for compressor control and engine electric cooling fan operation. Because the compressor is lubricated by oil suspended in the refrigerant, the EMS2000 prevents operation of the compressor unless there is a minimum refrigerant pressure, and thus refrigerant and oil, in the system. When refrigerant pressure increases the EMS2000 increases cooling fan speed to provide more airflow across the condenser.

Evaporator Temperature Sensor
The Evaporator Temperature Sensor is located on the left side of the heater case and signals directly to the BC1.
The sensor is an encapsulated thermistor that provides the BC1 with an input of the evaporator air outlet temperature.

Refrigerant Lines



To maintain similar flow velocities around the system, the diameter of the Refrigerant Lines varies to suit the two-pressure/temperature conditions. The larger diameters are installed in the low pressure/temperature zone and the smaller diameters are installed in the high pressure/temperature zone. Low and high pressure service fittings are incorporated into the refrigerant lines for system servicing.

Principle of Operation
The basic principle at work in a climate control system is heat transfer. An automotive A/C system takes heat from inside the passenger compartment and transfers it outside.

In an A/C system, heat is transferred using a refrigerant. The refrigerant absorbs heat from air entering the passenger compartment, carries the heat outside the compartment, releases the heat, and then re-enters the compartment to begin the cycle again.

An A/C system does not "add cold" to air - it removes some of the heat from it. Some heat is always present, but the less heat the air contains, the cooler it feels.

An air conditioning system's efficiency is based on how well it moves heat. Heat always travels from warm to cold. The reverse is never true. For example, if a hot cup of coffee is left standing, it will cool off, while a cold soda will get warm. The heat from the warm coffee moves to the cooler surrounding air. The heat from the surrounding air moves to the cooler soda, until a balance is reached.


Temperature and State Changes
At sea level, water freezes at 32° F (0° C) and boils at 212° F (100° C). These are the temperatures at which water changes state. When a liquid boils (changes to a gas), it absorbs heat. When a gas condenses (changes back to a liquid), it gives off heat:

- As the pressure on a liquid is increased, the boiling point rises.
- As the pressure on a liquid is decreased, the boiling point drops.

Evaporation
Evaporation is one of the basic principles by which a refrigeration system works. In evaporation, liquid changes to a vapor. Adding heat causes a liquid to evaporate.

Condensation
Condensation is the reverse of evaporation. In condensation, a vapor changes to a liquid. Removing heat causes a vapor to condense to a liquid.

The task of an air conditioning system is to absorb a large amount of heat, move it away from the passenger compartment, and exhaust it. When the refrigerant in the A/C system evaporates, it absorbs a large amount of heat from the air entering the passenger compartment.

As the refrigerant vapor is pumped outside the passenger compartment, it transports this heat with it. When the refrigerant condenses back into a liquid, this heat is released.

Compressor
When AC is requested, the clutch is energized and the pulley drives the shaft. The journal and the swash plate turn with the shaft, and the angled swash plate produces reciprocating movement of the pistons. Vapor from the inlet pressure chamber is drawn into the cylinder, compressed, and discharged into the outlet pressure chamber, producing a flow around the refrigerant circuit.

The flow rate through the compressor is determined by the length of the piston stroke, which is controlled by the tilt angle of the swash plate. The tilt angle of the swash plate is controlled by the servo pressure and compressor inlet pressure acting on the pistons during their induction stroke. A relative increase of inlet pressure over servo pressure moves the pistons along their cylinders to increase the tilt angle, the piston stroke and the flow rate. Similarly, a relative decrease of inlet pressure over servo pressure moves the pistons along their cylinders to reduce the tilt angle, the piston stroke and the flow rate.

The control valve regulates the servo pressure in the crankcase as a function of inlet pressure, so that the flow rate of the compressor matches the thermal load at the evaporator, i.e. the more cooling required in the passenger compartment, the higher the thermal load and flow rate. Servo pressure varies between inlet pressure and inlet pressure �0.07 bar (�1psi).

As the refrigerant flows through the evaporator and absorbs heat (i.e. as the thermal load increases) the pressure of the vapor entering the compressor increases. In the control valve, the increased inlet pressure causes the diaphragm and push rod to close the ball valve. The resulting reduction in crankcase pressure, together with the increase in inlet pressure, moves the swash plate to a higher tilt angle and increases the piston stroke and the flow through the compressor. When the thermal load of the evaporator decreases, the subsequent decrease in pressure of vapor entering the compressor causes the control valve to open. This increases swash plate crankcase pressure, which reduces the tilt angle of the swash plate and the flow through the compressor.

Condenser
The condenser, being directly downstream of the compressor, receives the high pressure vapor gas and the condensation process begins.

The unit is classified as an integrated, sub-cooling condenser and consists of a fin and tube heat exchanger installed between two end tanks. Divisions in the end tanks separate the heat exchanger into a three pass upper (condenser) section and a single pass lower (sub-cooler) section, which are interconnected by a receiver drier on the left hand end tank. The receiver/drier, containing a desiccant pack and filter, is a replaceable unit, located in a threaded housing at its lowest end and retained by a plastic bracket at the top of the condenser.

Ambient air, passing through the condenser due to ram effect and/or the cooling fan, absorbs heat from the refrigerant to change it from a vapor to a liquid. The condenser section cools and liquefies the refrigerant before it enters the receiver/drier.


Drier
From the condenser, liquid refrigerant under high pressure flows to the receiver/drier. The drier consists of a cylindrical tank to hold the refrigerant and a solid drier. The solid drier is made from zeoliite, molecular sieves and aluminum oxides. The drier is designed to separate the refrigerant vapor from the liquid so that only the liquid is fed to the expansion valve. After the refrigerant has passed through the condenser the remaining gas in the refrigerant liquefies and passes through the desiccant and filter removing moisture and solid impurities. The refrigerant flows into the sub-cooler section where it is further cooled resulting in the refrigerant at the outlet being almost 100% liquid.


Expansion Valve and Evaporator
The refrigerant, now a high pressure liquid is passed via the refrigerant lines to the expansion valve at the entrance to the evaporator. A ball and spring metering valve is installed in the inlet passage of the expansion valve. The metering valve is controlled by a temperature sensitive tube connected to a diaphragm. The top of the diaphragm senses evaporator outlet pressure and the tube senses evaporator outlet temperature.

Liquid refrigerant flows through the metering valve into the evaporator. The restriction across the metering valve reduces the pressure and temperature of the refrigerant. The restriction also changes the solid stream of refrigerant into a fine spray, to improve the evaporation process. As the refrigerant passes through the evaporator, it absorbs heat from the air flowing through the evaporator. The increase in temperature causes the refrigerant to vaporize.

The temperature and pressure of the refrigerant leaving the evaporator act on the diaphragm and temperature sensitive tube, which move to regulate the metering valve opening and so control the volume of refrigerant flowing through the evaporator. The more heat available to evaporate refrigerant the greater the volume of refrigerant allowed through the metering valve.

The refrigerant, now a low pressure gas full of latent heat removed from the passenger compartment is drawn back into the compressor. The compressor again increases the pressure of the refrigerant, making it now a high pressure vapor. This pressure increase raises the boiling point of the refrigerant, enabling it to give off heat and be condensed.


Heating System
The heating and ventilation system controls the temperature and distribution of air supplied to the vehicle interior. The system consists of a micro filter housing, a heater assembly, distribution ducts, refrigerant system and a control panel. The MINI heater system uses the air blend principle: fresh air enters through vents beneath the windshield and flows into the heater assembly, a blend flap mixes the warm air passing the heat exchanger with the cool air and distributes it into the vehicle interior. Flow-through vents incorporated in the luggage compartment enable the air to exit the vehicle interior.

Fresh or re-circulated air passes through the filter into the heater assembly where an electrical variable speed blower, and/or ram affect, forces the air through the system. Depending on the settings on the control panel, the air is then heated or cooled and supplied through the distribution ducts to face, defrost and floor level outlets.


Two different Heating Systems are provided depending on Climate Control variation (INKS or IHKA).




IHKA Heating and Air Distribution



The Heating and Air Distribution of IHKA systems differ from the IHKS system in the following ways:

- Two servomotors controlled by the IHKA module operate the temperature blend flap and air distribution mechanism. Flap position is monitored by the IHKA using potentiometers integrated in the servomotors.
- A heater core sensor measures the temperature of the air coming off the heat exchanger. The sensor is located on the right side of the front of the heater unit.
- A rocker switch and a power transistor (final stage) controls the blower motor at eight speeds. The blower speed is controlled manually via the rocker switch or automatically in the AUTO mode.


Switch Panel (IHKA)
An integral control panel on the IHKA module contains switches for system control inputs and a display to provide system status information.

The IHKA control system controls the operation of the refrigerant system and the control flaps in the heater assembly to control the temperature and distribution of air in the vehicle interior. It also outputs signals to the BC1 to control the fresh/re-circulation air servomotor and to the blower to control the air volume.

Display




The Display integrated into the IHKA will provide current temperature setting and fan speed information. The display will show LO or HI at the extreme temperature settings and indicate fan speed by the number of streamers illuminated around the fan blade. It is possible to display the temperature in °C or °F, changeable at the control unit.


Blower Switch




The blower speed control is adjusted by a horizontal rocker switch, with + and - on the right and left respectively. This switch provides manual control of blower speed. There are eight blower speeds. Each press of the blower switch will adjust the blower speed by one speed step in the appropriate direction. Pressing and holding the control will cause the fan speed to change every 0.8 seconds, until the control is released or the maximum or minimum speed is reached.

Blower speed will be indicated by a series of "streamer effect" bars arranged around the top edge of the central display panel. Each bar represents one speed step; eight bars are visible at maximum blower speed.

Blower speed will be controlled automatically if AUTO is selected. The blower will function 0.5 seconds after the end of cranking. If a problem occurs and the IHKA does not receive the end of cranking signal the blower would not be operational until the next crank, to avoid this, the blower will resume operation when the engine speed exceeds 400 rpm with the ignition in position 2 (engine running).


Defrost Switch (Programmed Defrost)
The programmed defrost mode is activated by briefly pressing the defrost switch. The LED in the switch flashing at 0.5 Hzsignals this to the driver.

The programmed defrost can be switched off by pressing the switch again or pressing one of the other air distribution switches. Pressing the AUTO or OFF button also deactivates the defrost function.

To distribute air to the windshield without activating the defrost program requires a long press of the defrost switch (> 2 seconds).


Air Distribution Control
Manual control of the air distribution is provided by three switches which control the distribution of air to the face, foot and windshield outlets. Each switch has a green LED to indicate that it has been selected. Pressing one of the switches will illuminate the LED and open the selected air outlet.

Air distribution will be controlled automatically if AUTO is selected.


Interior Temperature Sensor
The Interior Temperature Sensor is an encapsulated thermistor that provides the IHKA module with an input of passenger compartment air temperature. The sensor is installed in the right hand corner of the IHKA module and incorporates a fan to draw air from the vehicle interior over the sensor element.


Temperature Control Switch
The air temperature control is a rotary three-position switch, which is sprung to the center (rest) position. Rotating the control clockwise or anti-clockwise will increase or decrease respectively the desired temperature.

The rotary temperature control functions as follows:

- A momentary rotation increases or decreases the related temperature setting, in steps of 1° C (2° F), between 16° and 28° C (60° and 84° F).
- Switch held in the increase or decrease positions, step changes occur every 0.4 seconds until LO or HI is reached.
- Switch rotated in the decrease position when a temperature of 16° C (60° F) is set, the display changes to LO (maximum cold).
- Switch rotated in the increase position when a temperature of 28° C (84° F) is set, the display changes to HI (maximum hot).

Pressing the AUTO button for longer than two seconds can change the unit of measurement (°C/°F).


Heated Rear Window (HRW)
A momentary push switch controls the heated rear window and incorporates an orange LED to indicate status. A single press of the switch will turn the heated rear window on, illuminate the LED, and start a timer. When the timer has expired, the heated rear window and LED will turn off. The HRW is controlled by the BC1.


Heated Windshield (HFS)






The heated front screen is available as an option on all heater versions. For the IHKA system the heated front screen shares the same control switch and LED as the heated rear window. The heated front screen operation is timed dependent on the outside temperature and controlled by the BC1.

When the programmed defrost mode is requested with a short push on the defrost switch, all heated screens are switched on automatically. The LED will switch on only when the engine is running.


Fresh Air/Recirculation Switch
The fresh/recirculation air control is a momentary push switch with a green LED to indicate status. A single press of the switch will close the fresh air intake and illuminate the recirculation LED. Another press of the switch while the LED is illuminated will open the fresh air intake and extinguish the LED.

Air recirculation will be controlled automatically if AUTO is selected. This may be overridden by pressing the air recirculation control. Recirculated air will then remain manually controlled until the air recirculation control is pressed again.

AC Switch
Provides manual on/off control of the refrigerant system compressor. The AC can be switched off to reduce fuel consumption when there is no requirement for cool or dehumidified air. The AC control is a momentary push switch with a green LED to indicate status. A single press of the switch will provide the AC function and illuminate the LED; another press of the switch will switch off the AC function and extinguish the LED. Air conditioning compressor is automatically switched on when the AUTO switch is pressed.

Auto/Off Switch
The automatic mode is activated with a single press of the AUTO switch; the green LED illuminating indicates this to the driver. The air distribution and blower speed is controlled automatically, and the air conditioning is switched on when AUTO is active.
The driver can over-ride the automatic mode of the air distribution or blower by pressing one of the distribution buttons or manually adjusting the blower speed. When the blower is being controlled in AUTO mode the blower speed bars and fan symbol are not displayed in the central display panel. In the automatic mode, if the temperature is set to LO or HI, the blower runs at maximum speed with correction only for vehicle speed.
The IHKA control panel may also be switched off by using the OFF horizontal rocker switch. This will switch off the blower and air conditioning, distribution control functions and temperature control will also be switched off.

Solar Sensor
The solar sensor consists of a light sensitive diode that provides the IHKA module with inputs of sunlight intensity. The input is used as a measure of the solar heating effect on vehicle occupants. The sensor is installed in the center of the upper dash.

Heater Core Temperature Sensor
The heater core temperature sensor is an encapsulated thermistor that provides the IHKA module with air temperature of the heater core. The sensor is installed in the right hand side heater housing.