General

Climate Control-IHKS

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).





IHKS Heating and Air Distribution
The IHKS System allows manual selection of inlet air source, outlet air temperature, air distribution and blower speed. Components of the IHKS heating and air distribution system include:

- Micro filter
- Heater Assembly (including Air Conditioning System)
- Blower Motor and Resistor Pack
- Heater Core
- Control Flaps
- Distribution Ducts
- Outlet Vents

Micro filter
A pollen or combination pollen/odor filter (IHKA version) is fitted to all vehicles to improve the quality of the air supply to the vehicle interior.

Heater Assembly
The heater assembly heats/cools and distributes fresh or recirculated air as directed by selections made on the control panel. The assembly is installed on the vehicle centerline, between the dash and the firewall, and consists of a housing, which contains a blower, a heater core, control flaps, evaporator, expansion valve, and evaporator temperature sensor. A drain outlet in the bottom of the housing is connected to a tube installed in the right hand side of the tunnel that directs any condensate from the housing interior to beneath the vehicle.


Blower Motor and Resistor Pack
The blower is installed in the driver's side of the heater housing and consists of an open hub, centrifugal fan powered by an electric motor. A rotary switch on the control panel and a resistor pack control the four (4) blower speeds. At position 4 the resistor pack is bypassed allowing maximum blower voltage and speed. The resistor pack is installed in the air outlet from the blower, so that any heat generated within the resistor pack is dissipated by the airflow. Power is supplied to the resistor pack via an external relay controlled by the BC1.


Heater Core
The heater core provides the heat source for warm the air being supplied to the distribution outlets. The heater core is an aluminum double pass, fin and tube heat exchanger, installed through the left hand side of the housing. Two aluminum tubes attached to the heater core extend through the engine bulkhead to connect the heater assembly to the engine coolant system. When the engine is running, coolant is constantly circulated through the heater core by the engine coolant pump.


Control Flaps
Control flaps are installed in the heater assembly to control the inlet source, temperature and distribution of air.

Fresh/re-circulation Air Flap
The fresh/recirculation air flap is located in the micro filter housing and is operated by a servomotor. The BC1 controls the servomotor on request from the recirculation switch of the heater control panel.


The servomotor consists of a unidirectional electric motor with an integrated flap lever mechanism. The BC1 activates the servomotor for a maximum of 10 seconds to move the flap to one of the two end positions; no feedback on the actual position of the flap is received at the BC1 (maximum run time =10 seconds).



Temperature Flap


A blend flap regulates the temperature of the air leaving the heater unit by mixing heated air from the heater core with fresh or cooled air. A rotary temperature control operates the blend flap via a Bowden cable. The flap control mechanism and cable connection (1) is on the right side of the heater unit.


Air Distribution Flaps
Three distribution flaps are installed to control the flow of air to the footwalls, windshield/side windows and the face level outlets. The flaps are operated via a lever mechanism, linked to the air distribution knob on the control panel by a flexible control cable.








Distribution Ducts
Three separate distribution ducts are installed for air distribution:

- The windshield and front side window outlets ducts are integrated into the dash upper.
- The face level outlets and central high-level outlet duct are attached to the dash cross car beam.
- The rear footwell duct is located in the center of the heater assembly floor outlet and extends along the floor below the front seats.

Vent assemblies in the dash allow occupants to control the flow and direction of face level air. Each vent assembly incorporates a control knob to regulate flow and is moveable to control direction.



Rear Flow-Through Vents



The flow-through vents promote the free flow of heating and ventilation air through the cabin. The flow-through vents are located in the rear panel of the luggage compartment and vent cabin air into the sheltered area between the body and the rear bumper. The vents are effectively non-return valves and each consists of a grille covered by soft rubber flaps. The flaps open and close automatically depending of the differential between cabin and outside air pressures.


Switch Panel (IHKS)


The IHKS system uses three rotary control knobs for temperature, blower speed and air distribution control. The system has a recirculation function and may have the heated front screen as an option with the switch located in the blank above the heated rear window switch. The IHKS system also requests compressor activation from the BC1.


Temp Dial
Turning the temperature knob on the control panel operates the control cable and in turns the blend flap in the heater assembly. The blend flap varies the proportion of air bypassing and going through the heater core. The proportion varies between FULL COLD with no airflow through the heater core and FULL HOT with 100% of airflow through the heater core. This corresponds with the position of the temperature control knob.



Blower Dial
The blower operates while the ignition is on. Switch positions are OFF or one of four speeds. The blower will function 0.5 seconds after the end of cranking. At switch positions 1, 2 and 3, the blower switch connects the B+ side of the blower to different paths through the resistor pack, to produce corresponding differences of blower operating voltage and speed. At position 4, the blower switch connects a B+ directly to the blower, bypassing the resistor pack, and full battery voltage drives the blower at maximum speed.


Air Distribution Dial
Turning the distribution knob on the control panel operates the control cable to turn the distribution flaps in the heater assembly and direct air to the corresponding outlets in the passenger compartment.



Recirculation Button
When the fresh/recirculated air switch is pressed, the switch connects a ground to the BC1. The BC1 then grounds the indicator LED in the switch and the recirculated airside of the fresh/recirculation air servomotor. The indicator LED illuminates and the fresh/recirculation air servomotor moves the control flap in the filter housing to close the fresh air inlet and open the recirculated air inlet.


Compressor Button (Snowflake)
The Compressor Button operates a ground input to the BC1 to control the on/off selection of the refrigerant system. A green indicator LED in the AC switch illuminates when the air conditioning system is switched on.


Heated Rear Window Button (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 Front Windshield (HFS)
The heated front screen switch is located on the control panel above the heated rear window switch. The operation and configuration of the heated front screen control is identical to the heated rear window control.

IHKS Control Unit
The INKS System is a manual climate control. Operator input controls air temperature, air distribution, blower speeds and compressor requests. There are no "Automatic" functions with IHKS.


Temperature Control
The operator controls air outlet temperature by positioning the temperature knob. The knob controls the cable to the blend flap. The flap is linked internally to a secondary air-direction flap that optimizes airflow through the unit by ensuring the airflow does not enter the heater core area thereby preventing any unwanted hot/cold air bleed.
Engine coolant is flowing constantly through the heater core. There is no water valve. Failure of the flap to block off airflow through the heater core would provide constant heated air in the vehicle.


Blower Control
The Blower may only run if the ignition is on. There is a 0.5 second delay after engine cranking to energize the blower. This delay is controlled by the BC1. The BC1 receives the end of cranking (engine started) signal from the EMS2000. After a 0.5 second delay the BC1 energizes the Blower Relay. The Blower Relay supplies power to the 5 position blower switch (Off, 1, 2, 3, 4). Activation of the blower switch creates a power flow through the resistor pack (except in position 4). The varying voltage from the resistor pack is supplied to the blower and the BC1. The blower speed is based on the voltage supply from the resistor pack. Less resistance means higher voltage and higher blower speed. The BC1 looks for the blower speed voltage before requesting the AC compressor. Loss of blower voltage will result in loss of compressor.