General Information and Safety Precautions

Heater and air conditioner 1 – heater actuator 2 – fresh/recirculated air flap switch The switch is rigidly connected to the heater actuator and cannot be replaced separately. 3 – footwell nozzle 4 – heater duct for rear compartment 5 – connecting element 6 – footwell nozzle 7 – heater housing 8 – heat exchanger 9 – upper air duct 10 – additional blower resistor 11 – fresh/recirculated air flap actuator motor 12 – blower fan

CAUTION

The switch is illuminated by a light guide; there is only one incandescent bulb. To replace the bulb, remove the fan switch. Pull the bulb out of the socket with pliers. Starting from mid-1997 production, the bulb was replaced with an LED. The LED is not replaced separately.

Components of the heating, ventilation and air conditioning system located in the passenger compartment 1 – side window nozzles 2 – nozzles 3 – windshield defrost nozzle 4 – hot and fresh air controls 5 – spacer 6 – instrument panel cross member 7 – passenger compartment air filter 8 – fresh air/ventilation flap motor 9 – fresh air blower 10 – additional resistor with thermal fuse 11 – heating element 12 – center console 13 – foot area air outlet nozzle 14 – front duct 15 – seal 16 – connecting element 17 – heater control linkage 18 – heat exchanger 19 – heat exchanger/engine compartment bulkhead joint seal 20 – spacer for windshield defrost nozzles

Heater housing with heating and passenger compartment ventilation components 1 – heat exchanger After removal, the coolant must be completely replaced. 2 – self-tapping screw Required if the heat exchanger retaining tabs are broken. 3 – air distribution housing Do not disassemble. 4 – fresh air/recirculation flap motor 5 – self-tapping screw 6 – fresh air housing 7 – fresh air housing cover 8 – self-tapping screw 9 – additional resistor with overheat fuse 10 – self-tapping screw 11 – center flap lever 12 – temperature flap lever 13 – base 14 – heat exchanger/engine compartment bulkhead seal The seal has a mark on its end face. Install the seal so that the mark aligns with the marking on the base.

Passenger compartment air conditioning system diagram 1 – compressor 2 – compressor speed sensor 3 – electromagnetic clutch 4 – oil drain plug 5 – pressure relief valve 6 – connecting element with valve 7 – high pressure switch For air conditioner and electromagnetic clutch 8 – cover With seal, must always be secured. 9 – service connection On condenser. 10 – condenser 11 – threaded connection in refrigerant line 12 – throttle Integrated into connection –11–. 13 – evaporator 14 – low pressure switch \ refrigerant circuit 15 – connecting element with valve 16 – collection tank HD – high pressure side ND – low pressure side

Engine compartment layout of heating and air conditioning system components 1 – dust filter 2 – cover 3 – evaporator drain valve 4 – heater heat exchanger connectors 5 – air mode change flap (fresh air/recirculation) (N63) 6 – radiator cooling fan control (J293) 7 – vacuum reservoir 8 – vacuum hose 9 – air conditioner thermal switch 10 – condenser 11 – pressure reducing valve 12 – air conditioner clutch (N25) 13 – ambient air temperature sensor-switch (F38) 14 – air conditioner pressure sensor-switch (F129) 15 – receiver-dryer 16 – sight glass 17 – low and high pressure service valves 18 – expansion valve

General Information and Safety Precautions

Air supplied by the ventilation system into the passenger compartment through the filter can be heated or cooled depending on the selection by the driver and passengers. The heater or air conditioner is located in the passenger compartment, in the housing under the instrument panel. The entire airflow supplied into the compartment is directed through the same housing for heating or cooling. Air temperature and airflow speed are regulated using the controls located on the control panel.

Heat generated during engine operation is transferred by the coolant to the heater core located in the passenger compartment. The incoming airflow from the ventilation system passes through the core and is heated by the heat of the engine coolant flowing inside the core. The degree of heating is regulated by mixing cold and hot air in a set ratio using the blend air flap.

In cooling mode, the air conditioner removes excess heat and moisture from the passenger compartment in accordance with basic physical principles. CFC-free refrigerant (R 134a), which is environmentally friendly, circulates as a liquid in the high pressure part of the system, evaporates and turns into a gas in the low pressure section. When the gas expands, it cools down, absorbing heat from the air blown by the fan into the passenger compartment, and lowers its temperature. Then, as it passes through the condenser, the refrigerant releases the absorbed heat to the ambient air. The heat absorption cycle continues indefinitely as the refrigerant circulates in a closed circuit. Moisture is removed from the air supplied into the passenger compartment through condensation on the evaporator.

The air conditioner automatically keeps the set passenger compartment temperature constant.

The Climatronic climate control system, unlike a conventional air conditioner, automatically regulates the air volume and distribution in addition to the temperature. Air volume is regulated smoothly by changing the blower speed depending on the difference between the set temperature and the passenger compartment temperature.

Climatronic additionally has a solar sensor that detects solar radiation. It is located in the center of the instrument panel under the windshield. At particularly high solar radiation, the solar sensor automatically affects the blower speed through the electronic control system, and thus the volume of air supplied into the passenger compartment. The set passenger compartment temperature is adjusted in accordance with solar radiation.

Compressor, driven by an electric motor.

The electronic control unit is integrated into the air conditioner control unit. When the blower speed is set manually below the minimum, the heating/air conditioning system switches off.

Faults that occur in the control module, sensors and actuators are stored in the control module fault memory. A special scan tool is used to read the fault codes.

The air conditioning system presents a potential hazard. Certain precautions must be observed when servicing it. Most repair and maintenance operations on the air conditioning system require special equipment and specific skills.

Body ventilation is provided by a through-flow of air. Fresh air enters the vehicle through the air intake located in front of the windshield. The airflow exits through the outlet ducts located under the rear bumper.

The air flow volume is controlled by a four-speed blower fan.

The blend-air type heater system is designed to respond quickly to changes in cabin air temperature and to reduce fluctuation of the heated air temperature. Engine coolant constantly circulates through the heater core and the coolant flow is not regulated. The controlled factor is air temperature, which is changed by the blend door that determines the amount of air passing through the heater core before it enters the cabin.

A recirculation mode is provided to prevent outside air from entering the cabin.

Air Conditioning Service Precautions

The air conditioning system must be serviced only by trained technical personnel who are instructed in safe working practices using proper equipment, observe the discharge procedures, and are familiar with the recovery and storage procedures for automotive refrigerant.

Do not allow refrigerant to contact the skin.

Wear protective goggles when working near the air conditioning system.

If refrigerant contacts the skin or eyes, do not rub the affected area. Immediately flush with cold water for at least 15 minutes. Seek medical attention immediately at a doctor or medical facility. Do not self-medicate.

Refrigerant in a new cylinder is stored under pressure. Store the cylinder at a temperature not exceeding 50°C. Take precautions to prevent the cylinder from falling from a height or any other situation that could damage it.

Work must be performed in a well-ventilated area. Refrigerant evaporates quickly, reducing the oxygen supply and causing difficulty breathing.

Gaseous refrigerant is heavier than air and will relatively quickly settle at low levels, for example under the vehicle. Burning refrigerant produces poisonous gas. Keep refrigerant away from open flames. Do not smoke. When using a halide leak detector, avoid inhaling the smoke.

When performing welding work near the air conditioning system, avoid exposing it to high temperature or open flame. Overheating can cause pressure in the system to rise and may cause ignition.

Do not clean the condenser or evaporator with steam. Use only cold water or compressed air.

A 4-speed fresh air blower fan is used to increase air circulation. Resistors are switched in so that the fan runs at different speeds at each stage. The resistors are located in the connector board on the fan. If faults occur, the connector board is replaced as an assembly.

If fresh air should not be drawn in, for example when outside air is poor, pressing the recirculation button switches to air recirculation. In this mode, air circulates only inside the cabin. The switch moves the door by means of a small electric motor.

CAUTION

If the "Windshield defrost mode" is activated, i.e. the air distributor switch is set to the upper end position, recirculation mode is not possible. The A3 may also be equipped with air conditioning. Repair of the air conditioner is not described here. This work must be performed at a specialist workshop. Do not open the air conditioning refrigerant circuit, as contact of the refrigerant with skin may cause frostbite. If refrigerant contacts skin, immediately rinse the affected area with cold water for at least 15 min. The refrigerant is colorless and odorless, and is heavier than air. In case of refrigerant leaks, there is a risk of poisoning near the floor or in the lower part of the vehicle (the presence of refrigerant cannot be felt). If refrigerant contacts skin, immediately rinse the affected area with cold water for at least 15 min. The refrigerant is colorless and odorless, and is heavier than air. In case of refrigerant leaks, there is a risk of poisoning near the floor or in the lower part of the vehicle (the presence of refrigerant cannot be felt).