| Blowing out refrigerant circuit with compressed air and nitrogen |
| Vehicles with high-voltage system (hybrid vehicles) |
WARNING | Safety hazard: the engine can start unexpectedly. |
| Before carrying out general work on a vehicle with high-voltage electrical system, switch off the ignition and remove the ignition key from the vehicle. |
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WARNING | Working on vehicles with high-voltage wiring: |
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| Do not support yourself or tools on high-voltage wiring or associated components --> this can damage the insulation. |
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| High-voltage wiring must not be excessively bent or kinked --> this can damage the insulation. |
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| The round high-voltage connectors are colour-coded with an external coloured ring and are provided with mechanical coding or guide lugs. It is important to observe this coding when joining up the round high-voltage connectors, otherwise the connectors can be damaged. |
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DANGER! | Risk of fatal injury if high-voltage components are damaged. |
| Observe the following when working in the vicinity of high-voltage components or wiring: |
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| It is not permitted to use cutting or forming tools, other sharp-edged tools or heat sources such as welding, brazing, soldering, hot air or thermal bonding equipment. |
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| Before starting work, visually inspect the high-voltage components in the areas involved. |
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| Before working in the engine compartment, visually inspect the power electronics -JX1-, electric drive motor -V141-, air conditioner compressor -V470- and high-voltage wiring. |
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| Before working on the vehicle underbody, visually inspect the high-voltage wiring and covers. |
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| Before working on the rear section of the vehicle, visually inspect the high-voltage wiring and the electro-box with the maintenance connector for high-voltage system - TW -. |
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| Visually inspect all potential equalisation lines. |
| Check the following when making the visual inspection: |
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| There must be no external damage on any component. |
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| The insulation of the high-voltage wiring and potential equalisation lines must not be damaged. |
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| There must be no unusual deformation of the high-voltage wiring. |
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| All high-voltage components must be identified by a red warning sticker. |
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| If work is necessary in the vicinity of high-voltage system components, perform a visual inspection of the high-voltage components and wiring to check for damage → Chapter and note → Electrical system; Rep. gr.93. |
| De-energising high-voltage system |
DANGER! | Voltage can cause fatal injury. |
| Danger of severe or fatal injuries from electric shock. |
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| For reasons of safety, persons with life-preserving or other electronic medical devices in or on their body must not perform any work on the high-voltage system. Such medical devices include internal analgesic pumps, implanted defibrillators, pacemakers, insulin pumps and hearing aids. |
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| The high-voltage system may only be de-energised by a suitably qualified person (Audi high-voltage technician). |
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| It must be definitely confirmed that the high-voltage system is de-energised. The system may only be de-energised using the vehicle diagnostic tester via „Guided Fault Finding“. |
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| The qualified person (Audi high-voltage technician) confirms that the system is de-energised and uses the locking cap -T40262- to ensure that the system cannot be re-energised. The ignition key and the maintenance connector for high-voltage system - TW - should then be stored in a safe place by the qualified person. |
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| The qualified person (Audi high-voltage technician) marks the vehicle by attaching the appropriate warning signs. |
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Note | t
| De-energising high-voltage system: |
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| Connect vehicle diagnostic tester |
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| Select Guided Fault Finding mode |
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| Using the Go to key, select the following menu items in succession |
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| Function/component selection |
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| Self-diagnosis compatible systems |
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| 8C - Hybrid battery management -J840 |
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| 8C - Hybrid battery management, functions |
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| 51 - De-energise high-voltage system (Rep. gr. 93) |
| Re-energising high-voltage system |
DANGER! | Voltage can cause fatal injury. |
| Danger of severe or fatal injuries from electric shock. |
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| For reasons of safety, persons with life-preserving or other electronic medical devices in or on their body must not perform any work on the high-voltage system. Such medical devices include internal analgesic pumps, implanted defibrillators, pacemakers, insulin pumps and hearing aids. |
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| The high-voltage system may only be re-energised by a suitably qualified person (Audi high-voltage technician). |
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| The system may only be re-energised using the vehicle diagnostic tester via „Guided Fault Finding“. |
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| The vehicle is then made ready for operation again by the qualified person (Audi high-voltage technician). |
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| The qualified person (Audi high-voltage technician) marks the vehicle by attaching the appropriate warning signs. |
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Note | t
| Re-energise high-voltage system: |
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| Connect vehicle diagnostic tester |
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| Select Guided Fault Finding mode |
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| Using the Go to key, select the following menu items in succession |
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| Function/component selection |
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| Self-diagnosis compatible systems |
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| 8C - Hybrid battery management -J840 |
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| 8C - Hybrid battery management, functions |
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| 51 - Re-energise high-voltage system (Rep. gr. 93) |
DANGER! | When working on a vehicle with the ignition switched on or while the drive system is active, the engine can start unexpectedly and exhaust fumes can cause a health hazard in closed rooms. Moving parts can trap or draw in parts of the body and/or clothing (safety hazard). |
| Before switching on the ignition, perform the following steps: |
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| Move selector lever to position P |
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| Connect battery charger (e.g. -VAS 5095A-) to jump-start connections of 12 V electrical system |
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| For test and measurement work that requires the vehicle's drive system to be active or the ignition to be switched on, move the selector lever to position „P“, activate the parking brake and arrange the tools needed so that they cannot come into contact with moving components of the engine and so that they cannot even come near to components that turn when the engine is running. |
Note | t
| Move the selector lever to position „P“ and activate the parking brake before performing test and measurement work for which the ignition must be switched on but where the vehicle's drive system does not need to be active. |
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| The status of the drive system is shown by the control unit in dash panel insert -J285- via the „power meter“ → Owner's Manual. |
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| Activating and deactivating drive system → Owner's Manual (note display of control unit in dash panel insert -J285-). |
| The best way of removing moisture, impurities and old refrigerant oil from the refrigerant circuit without any unnecessary loss of refrigerant and without extensive assembly work, whilst at the same time ensuring environmental compatibility, is to flush the refrigerant circuit with refrigerant R134a or to blow it out with compressed air and nitrogen. |
Note | t
| Blowing out the refrigerant circuit with compressed air and nitrogen usually involves far more work than flushing with refrigerant R134a. Flushing with refrigerant R134a also provides far better cleaning of the components. Flushing should therefore always be employed in the event of complaints (blowing out should only be applied when dealing with certain problems and for particular components). |
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| Under certain conditions it may, for example, be sufficient to blow out specific components (e.g. individual refrigerant pipes or refrigerant hoses) with compressed air and nitrogen (for instance to force old refrigerant oil out of individual components following removal). |
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| Certain impurities are impossible or difficult to remove properly from the refrigerant circuit using compressed air. Such impurities can be removed for example by flushing with refrigerant R134a → Chapter. |
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| A maximum working pressure of 15 bar is not to be exceeded when blowing out (corresponds to the pressure prevailing in a charged refrigerant circuit at an ambient temperature of approx. 60 °C; use pressure reducer for compressed air as well if applicable). |
WARNING | t
| Nitrogen can escape from the bottle in an uncontrolled way. |
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| Only use pressure reducer for nitrogen cylinders (max. working pressure 15 bar). |
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| Use appropriate extraction units to draw off the gas mixture escaping from the components. |
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| Always flush or blow out components in the direction opposite to refrigerant flow. |
Note | The restrictor, expansion valve, air conditioner compressor, receiver and reservoir cannot be flushed with compressed air and nitrogen. |
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| In the case of condensers fitted with a dryer cartridge in the integrated receiver, this cartridge is to be removed. |
Note | t
| In the case of condensers with an integrated receiver / dryer cartridge which cannot be renewed separately, the condenser is to be renewed after flushing. |
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| Depending on the version, receivers on which the dryer cartridge can be renewed separately may be provided with an additional filter element which may have to be renewed together with the dryer cartridge. |
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| First flush out the old refrigerant oil and dirt with compressed air and then use nitrogen to remove the moisture from the components. |
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| For adapter for connecting pressure hose to refrigerant circuit, refer to → Chapter. |
| Observe the following to prevent oil and moisture from the compressed-air system from ingressing into the refrigerant circuit. |
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| The compressed air must be passed through a compressed-air purifier for cleaning and drying. Use is therefore to be made of filters and dryers for compressed air (included in the scope of delivery as tool for painting work) → Workshop equipment and special tools catalogue. |
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| For refrigerant lines with a thread or union nut at the connection, make use of adapters from the adapter set for refrigerant circuit -V.A.G 1785- (adapter -V.A.G 1785/1- to adapter -V.A.G 1785/8-) for connection of the 5/8" -18 UNF charging hoses (some of these adapters are also contained in the VW/Audi passenger vehicle adapter set -VAS 6338/1-). |
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| For refrigerant pipes with no thread or union nut at connection (for connecting adapters), use adapters from adapter set for refrigerant circuits -VAS 6338/1- or commercially available blow-out gun with rubber mouthpiece. |
Note | t
| The refrigerant circuit is only to be blown out with compressed air and then nitrogen if no means of flushing the refrigerant circuit are available or if flushing of individual components would involve too much work (blowing minor impurities and small quantities of moisture out of refrigerant lines for example is not particularly time-consuming). |
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| Compressed air/nitrogen emerging from the components is to be drawn off by way of an appropriate system (e.g. workshop extraction system). |
| The refrigerant circuit (or individual components) is/are to be blown out if no means of flushing are available or if flushing seems inappropriate |
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| In the event of dirt or other impurities in individual circuit components. |
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| If the vacuum reading is not maintained on evacuating a leak-free refrigerant circuit (pressure build-up due to moisture in refrigerant circuit). |
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| If the refrigerant circuit has been left open for longer than the normal assembly time (e.g. following an accident). |
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| If pressure and temperature measurements in the refrigerant circuit indicate the likelihood of moisture. |
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| If there are doubts about the amount of refrigerant oil in the refrigerant circuit. |
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| If the air conditioner compressor has to be renewed on account of internal damage (e.g. noise or no output). |
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| If stipulated by the vehicle-specific Workshop Manual after renewing certain components |
Note | Certain impurities and old refrigerant oil are impossible or difficult to remove properly from the refrigerant circuit using compressed air. Such impurities can be removed for example by flushing with refrigerant R134a → Chapter. |
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