2000 Audi A8 S8 Service & Repair Manual

1997-2003 HVAC Air Conditioning - A8 & S8 A/C REFRIGERANT SYSTEM (R-134A), SAFETY MEASURES  The subassemblies and lines of the air conditioner are filled with tetrafluoroethane also known as refrigerant R-134a.  Refrigerant R-134a replaces the refrigerant R-12 which is reported to have harmful effects on the earth's ozone layer.  R-134a and R-12 systems are similar in design but there are very important differences in the refrigerants, lubricating oils, service equipment and A/C system components. If liquid refrigerant has come in contact with your skin or eyes:  Do not rub skin or eyes  Immediately flush with cool water for 15 minutes  Rush to a doctor or hospital  Do not attempt to treat yourself WARNING:  Always use an Underwriter's Laboratory (UL) approved refrigerant recovery/recycling/recharging unit such as Kent-Moore ACR 4 , or equivalent, whenever discharging an R-134a A/C system.  As of January 1, 1992 any person who services a motor vehicle air conditioner MUST, by law, be properly trained and certified and use approve refrigerant recycling equipment. Technicians must complete an EPA approved recycling course to be certified.  State and Provincial governments may have additional requirements regarding air conditioning servicing. Always comply with state and local laws. WARNING:  A/C system is filled with refrigerant which is under pressure.  Refrigerant must not come in contact with your skin. WARNING:  Switch on existing exhaust/ventilation systems when working on the refrigerant system.  Work in a well ventilated area because refrigerants are heavier than air, displace oxygen and may cause suffocation in areas of poor air circulation, like under the car.  Avoid breathing refrigerant vapors. Exposure may irritate eyes, nose and throat.  Always wear hand and eye protection (gloves and goggles) when 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

working around the A/C refrigerant system.  Do not expose any component of the A/C system to high temperatures (above 80° C/176°F) or open flames. Excessive heat will cause a pressure increase which could burst the system. WARNING:  Keep refrigerant containers stored below 50°C (122°F) and never drop from high places. DO NOT warm refrigerant containers with an open flame. If refrigerant needs to be warmed, place bottom of tank in warm water.  Keep refrigerant away from open flames because poisonous gas will be produced if it burns. Do not smoke when refrigerant are present for the same reason.  Electric welding near refrigerant hoses causes R-134a to decompose from ultraviolet light. Discharge system before electric welding.  Pressurized R-134a refrigerant in the presence of oxygen may form a combustible mixture. Never introduce compressed air into any closed R-134a container (full or empty), A/C component or piece of service equipment.  DO NOT exceed maximum rated capacity of refrigerant containers. Never fill a container to more than 60% of its gross weight rating (for example, 18 lb. in a 30 lb. container.) Without sufficient room for expansion of R-134a (gas cushion), the container could explode when the temperature rises causing serious injury.  Do not steam clean condensers or evaporators. Use only cold water or compressed air. CAUTION:  R-12 and R-134a refrigerants are NOT compatible. Never add R-12 refrigerant to an R-134a system or R-134a refrigerant to an R-12 system. If the refrigerants are mixed, total system contamination will occur and compressor failure may result.  Refrigerant oils used for the R-134a system and R-12 system are NOT compatible. Use only the specified synthetic oil (Polyalkylene Glycol/PAG) for the R-134a refrigerant system. DO NOT use R-12 system oil in an R-134a system or R-134a system oil in an R-12 system. If the refrigerant oils are mixed, system contamination will occur and compressor failure may result.  R-134a refrigerant system oil (PAG oil) absorbs moisture very rapidly. Moisture combines with the refrigerant to form acids which will damage the system. Use only the specified oil from a sealed container and ALWAYS reseal oil container immediately after use. DO NOT use oil if it has become contaminated with moisture or if container has been left open.  Immediately plug open connections on A/C components to prevent 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

dirt and moisture contamination. Likewise, DO NOT remove new component from packaging until ready to install. Immediately tighten component connections after installation. CAUTION:  Always use separate refrigerant recovery/recycling/recharging servicing equipment for R-12 and R-134a systems. DO NOT use one piece of equipment for both R-12 and R-134a systems. The residual traces of refrigerant will contaminate and damage the equipment. Servicing equipment includes recovery/recycling/recharging unit, charging station, vacuum pump, manifold gauges, etc.  DO NOT use R-12 servicing equipment on R-134a systems or R-134a equipment on R-12 systems or damage to both the vehicle A/C system and servicing equipment may result. Use only equipment designed to meet Society of Automotive Engineers (SAE) standards.  R-134a and R-12 systems use different size service fittings. NEVER use adapters to convert an R-12 fitting to R-134a size or R-134a fitting to R-12 size.  R-134a and R-12 A/C components including compressor, hoses, O- rings, evaporator, condenser, receiver-drier, etc. are NOT interchangeable. Components of the R-134a system are identified by lettering "R-134a" or by a green label (or stripe). In addition, a label on the evaporator housing (below plenum tray) identifies which type of refrigerant is used. Use only the correct system component for each refrigerant type. CAUTION:  Always replace damaged and/or leaking A/C system components. Do not attempt repair by soldering, brazing or welding.  Work area must be extremely clean when working on A/C system components.  Use only tools, equipment and parts specified for use with R-134a.  Switch on existing exhaust/ventilation systems when working on the refrigerant system.  Discharge A/C system using refrigerant recovery/recycling/recharging unit Kent-Moore ACR 4 , or equivalent, before removing any A/C system component.  After emptying A/C refrigerant, disconnect power supply from A/C clutch -N25- (e.g. unplug connector from A/C refrigerant low pressure switch -F73-) to prevent accidental compressor operation with A/C system discharged.  Always replace O-rings, DO NOT reuse. Use only the correct size and type of O-rings specified for use with R-134a refrigerant. Lubricate O- ring with refrigerant - oil before installing.  Always reinstall cap(s) over A/C service valve(s). 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

A/C REFRIGERANT SYSTEM, GENERAL REPAIR GUIDELINES The refrigerant circuit of the air conditioning system must not be drained and opened (See A/C REFRIGERANT SYSTEM (R - 134A), SAFETY MEASURES ) unless this is necessary because of safety precautions or unless components of the refrigerant circuit of the air conditioning system have to be replaced. When performing all other usual vehicle repair work, the refrigerant circuit of the air conditioning system should also remain closed. Servicing operations which can be performed on the heating and air conditioning system without opening the refrigerant circuit, are described in A/C SYSTEM REFRIGERANT SYSTEM, SERVICING . For servicing operations to A/C system that require discharging the refrigerant circuit. See A/C REFRIGERANT SYSTEM (R - 134A), DISCHARGING . A/C REFRIGERANT R-134A, PROPERTIES Commercial designation Obtain R-134a refrigerant (tetrafluoroethane) from a local A/C supplier under one of the following names  H-FKW 134a  SUVA(R) 134a  KLEA 134a Color Refrigerant R-134a is colorless and is invisible as a gas. Only the layer between gas and fluid is visible (fluid level in tube of cylinder or bubbles in sight glass in fluid reservoir.) R-134a when viewed through a sight glass (if installed) may appear milky due to the mixing of refrigerant and lubricating oil (PAG oil). Airborne properties Escaped refrigerant gases are heavier than air and will gather first in low places, like under the car. R-134a refrigerant gas displaces oxygen and may cause suffocation in low areas of poor air circulation. Solubility of refrigerant oil NOTE: The connections for switches mentioned in this Repair Manual are provided with a valve which closes automatically when the switches are unscrewed. These switches can thus be replaced even though the refrigerant circuit is fully charged. NOTE: R-134a refrigerant is packaged in different containers. Use only R-134a that comes in containers having correct types of service fitting. 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

A required special refrigerant oil Polyalkylene Glycol (PAG) synthetic oil is used to lubricate cylinder walls and bearings and enters the refrigerant circuit to some degree. This oil is NOT compatible with mineral based oils used in R-12 systems. Effects on the environment Because R-134a does not contain chlorine atoms, the major catalyst in ozone depletion, R-134a has no ozone depletion potential. R-134a does not cause smog and has a considerably lower global warming potential (greenhouse effect) than R- 12 refrigerant. Nonetheless, do not release R-134a into the environment and always recover/recycle using approved service equipment. Toxicity Refrigerant R-134a is non-toxic up to a temperature of 101°C (214°F) and is safe when handled and used properly. Above 101°C (214°F), gas pressure is above 39.5 bar (573 psi) and R-134a begins to decompose into poisonous gases (hydrogen fluoride, carbonyl fluoride and fluorine). These gases give adequate warning of their presence since they cause irritation of the mucous membrane (throat). Refrigerant R-134a gas has no effect on foodstuffs; it does not poison food or make it inedible. Temperature/pressure relationship In a not fully charged refrigerant container, refrigerant gas comes to the surface which under particle formation becomes fluid. This occurs under pressure and is know as gas pressure. Similar to R-12 refrigerant, the gas pressure of R-134a is temperature dependent. TEMPERATURE\PRESSURE RELATIONSHIP NOTE: R12 refrigerant systems use mineral oils which are not dissolved by R-134a refrigerant and are unusable. Temperature in °C (°F) Pressure in bar (psi) -30 (-22) 0.0 (0.0) -20 (-4) 0.3 (4.4) -10 (14) 1.0 (14.5) 0 (32) 1.9 (27.5) 10 (50) 3.1 (45.0) 20 (68) 4.7 (68.2) 30 (86) 6.7 (97.2) 40 (104) 9.1 (132.0) 50 (122) 12.2 (177.0) 60 (140) 15.8 (229.2) 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

 While performing body/paint repairs involving the use of preheating or drying ovens, do not expose any component of A/C system to temperatures above 80°C/176°F.  Excessive heat will cause a pressure increase which could burst the system.  Temperature/pressure chart. See A/C REFRIGERANT SYSTEM (R - 134A), PRESSURE & TEMPERATURE RELATIONSHIPS . Effects on plastics Refrigerant R-134a will deteriorate some plastics. When system temperature drops, these plastics can be deposited at the expansion valve or restrictor causing blockage. Therefore, when making system repairs, use only genuine Audi replacement parts which are specified for use with R-134a refrigerant. Effects on metal In its pure state, refrigerant R-134a is chemically stable and will not attack iron or aluminum. However, the mixture of R-134a and PAG oil may deteriorate certain metals (copper) which could lead to blockage, leaks or deposits on the compressor piston. Therefore, when making system repairs, use only genuine Audi replacement parts which are specified for use with R-134a refrigerant. Critical temperature/critical pressure R-134a refrigerant will remain chemically stable up to a pressure of 39.5 bar (573 psi). This corresponds to a temperature of 110°C (230°F). Above this temperature the refrigerant deteriorates (see flammability). Water solubility Liquid R-134a refrigerant will absorb only very minute quantities of moisture. However, R-134a vapor can absorb large amounts of moisture. Water in the system forms ice in the expansion valve or restrictor causing the system to stop cooling. In addition, moisture combines with the refrigerant to form acids which will damage the system. Flammability R-134a refrigerant is not flammable. In fact, it tends to inhibit combustion and has a fire extinguishing effect. However, a flame or glowing hot surface, as well as ultraviolet light (from electric welding), will decompose the refrigerant into poisonous gases (hydrogen fluoride, carbonyl fluoride and fluorine). These gases give adequate warning of their presence since they cause irritation of the mucous membrane (throat). R-134a can become flammable at pressures above ambient pressure in conjunction with air concentrations greater than 60% by volume. 70 (158) 20.2 (293.0) WARNING: Paint repairs on vehicles with A/C: 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

Refrigerant containers There must be pressure space available in the fluid area of the container. At increasing temperatures the fluid expands, the space filled with vapor becoming smaller. At a specific point there will only be fluid in the container. Beyond this point, only a slight increase in temperature will result in a very high pressure in the container. Without sufficient room for expansion of R-134a (gas cushion), the container could explode when the temperature rises causing serious injury. DO NOT exceed maximum rated capacity of refrigerant containers. Never fill a container to more than 60% of its gross weight rating (for example, 18 lb in a 30 lb container.) Leak detection Use halogen leak detector Hitec HI400A-TEL, or equivalent, to check for R-134a system leaks. This tool can also be used to detect leaks in R-12 systems. Many currently available R-12 leak detectors cannot detect R-134a refrigerant leaks. A/C REFRIGERANT OIL (PAG), PROPERTIES A special Polyalkylene Glycol (PAG) synthetic oil is used in R-134a systems. This oil is NOT compatible with mineral based oils used in R-12 systems. See safety measures under A/C REFRIGERANT SYSTEM (R - 134A), SAFETY MEASURES for Warnings and Cautions regarding proper oil usage. A/C REFRIGERANT SYSTEM (R-134A), IDENTIFICATION Refrigerant system with restrictor and accumulator CAUTION:  Refrigerant oils used for the R-134a system and R-12 system are NOT compatible. Use only the specified synthetic oil for the R-134a refrigerant system. DO NOT use R-12 system oil in an R-134a system or R-134a system oil in an R-12 system. If the refrigerant oils are mixed, system contamination will occur and compressor failure may result.  R-134a refrigerant system oil (PAG oil) absorbs moisture very rapidly. Moisture combines with the refrigerant to form acids which will damage the system. Use only the specified oil from a sealed container and ALWAYS reseal oil container immediately after use. DO NOT use oil if it has become contaminated with moisture or if container has been left open.  Do not allow refrigerant oil to come in contact with engine oil, transmission fluid or painted vehicle surfaces (for example when disposing). Dispose of used PAG refrigerant oil separately following laws governing hazardous waste disposal. 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

1. Compressor 2. Condenser 3. Restrictor 4. Evaporator 5. Accumulator Fig. 1: Identifying Refrigerant System With Restrictor (Orifice Tube) And Accumulator Courtesy of AUDI OF AMERICA, INC. A/C REFRIGERANT SYSTEM (R-134A), COMPONENT OVERVIEW A/C compressor NOTE: Arrows indicate direction of refrigerant flow. 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

The compressor is driven via a belt on the engine when the A/C clutch engages (A/C ON). Low pressure refrigerant gas from the evaporator is compressed by the compressor. After compression, the refrigerant gas (now high pressure) flows to the condenser. The variable displacement A/C compressor varies piston stroke and output depending on load requirements and suction pressure. NOTE:  The compressor contains PAG type refrigerant oil that is mixable under all temperatures with refrigerant R-134a.  A label on the compressor indicates that compressor is for R-134a systems only. 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

Fig. 2: Identifying A/C Compressor Courtesy of AUDI OF AMERICA, INC. A/C condenser The condenser transfers heat from the compressed refrigerant gas to the outside air which causes the refrigerant to change state from a gas to a liquid. 2000 Audi A8 L Quattro 1997-2003 HVAC Air Conditioning - A8 & S8

2000 Audi A8 S8 Service & Repair Manual

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