Audi Workshop Service and Repair Manuals

Tracing leaks in refrigerant circuit with leak detection system VAS 6201 Vehicles with high-voltage system (hybrid vehicles) For all work on vehicles with a high-voltage system, note the additional warning instructions for working on such vehicles → Chapter „Warning instructions when working on vehicles with high-voltage system“ and → Electrical system; Rep. gr.93. All vehicles   Note t  Certain leaks are difficult or even impossible to find using an electronic leak detector. In such cases, the leak detection system VAS 6201 can be used. t  Refrigerant circuit leaks result in a loss of refrigerant oil together with the refrigerant. This oil generally remains in the vicinity of the leak location. Adding a small quantity of fluorescent fluid to the refrigerant circuit makes this oil visible under UV light. The fluid (PAG oil containing an additive which shows up under UV light) is poured into the refrigerant circuit and becomes distributed with the refrigerant oil when the air conditioner is switched on. t  The air conditioner must be operated for at least 60 min. to distribute the additive throughout the refrigerant circuit (the air conditioner compressor must run). Depending on the extent of the leak, the leakage location may already become visible under UV light within this period. t  The refrigerant oil containing the additive (which shows up under UV light) can either be poured directly into the open circuit or pumped in with the circuit charged using the hand pump VAS 6201/1 (from the leak detection system VAS 6201) via the service connection on the low-pressure end. t  If the UV leak detection additive is applied via the service connection on the low-pressure end with the refrigerant circuit charged, a small quantity of UV leak detection additive remains in the service connection. This is to be carefully removed so as to avoid subsequent erroneous leak detection. t  If a component forming part of a circuit into which the UV leak detection additive is poured has to be renewed, thoroughly clean the joints with the other components after assembling the refrigerant circuit. Otherwise, the residual UV leak detection additive at the joint could be erroneously identified as a leakage location during subsequent leak localisation. t  On discharging the refrigerant circuit, refrigeration oil and thus also UV leak detection additive ingresses into the air conditioner service station. The refrigerant oil is removed from the refrigerant in the oil separator of the air conditioner service station and discharged from the air conditioner service station via the drain. The refrigerant oil drained off is not to be poured back in. It is to be replaced with fresh refrigerant oil. t  Observe the following if leak detection fluid has already been poured into a refrigerant circuit in the course of previous repair work: Only add new leak detection fluid if refrigerant oil is renewed. If only a certain amount of refrigerant oil has been renewed, just add the corresponding quantity of leak detection fluid. After renewing 100 ml of refrigeration oil on a vehicle containing 250 ml for example, just add 1 ml (cm3) of UV leak detection additive. t  Certain materials and their compounds (e.g. oxidation products on aluminium components, anti-corrosion waxes) also show up under UV light. t  Certain types of air conditioner service station permit the direct introduction of the UV leak detection additive (heed the information given in the operating instructions of the air conditioner service station). Proceed as follows with a completely empty refrigerant circuit to avoid allowing more refrigerant than is absolutely necessary for leak detection to escape into the environment when localising refrigerant circuit leaks: –  Evacuate the refrigerant circuit using the air conditioner service station → Chapter.   Note t  If evacuation already reveals a major leak, this is to be located and eliminated as described → Chapter and → Chapter. t  With the leak detection system -VAS 6201-, it is also possible to add UV leak detection additive to a charged or open refrigerant circuit → Anchor. Continue as follows if evacuation does not reveal any leakage or if the leakage is so slight that it is not possible to determine the leakage location on evacuation: t  Adding UV leak detection additive to the refrigerant circuit using the air conditioner service station → Anchor. t  Adding UV leak detection additive to the refrigerant circuit using the leak detection system -VAS 6201- → Anchor. Adding UV leak detection additive to the refrigerant circuit using the air conditioner service station –  Adding UV leak detection additive and the specified quantity of refrigerant to the refrigerant circuit using the air conditioner service station → Chapter.   Note The quantity of UV leak detection additive to be added to a refrigerant circuit with a refrigeration oil quantity of 100 to 150 cm3 using the hand pump -VAS 6201- of the leak detection system -VAS 6201- is 2.5 +/- 0.5 cm3. If the quantity of refrigeration oil in the refrigerant circuit is greater, correspondingly more UV leak detection additive must be added (e.g. .5.0 +/- 0.5 cm3 for a refrigerant circuit with a refrigeration oil quantity of 250 cm3. When adding the UV leak detection additive with an air conditioner service station, the amount required may differ and attention must therefore be paid to the corresponding operating instructions. For the corresponding refrigeration oil quantity in the refrigerant circuit, refer to → Chapter. Special tools and workshop equipment required t  Air conditioner service station with facility for adding UV leak detection additive to the refrigerant circuit → V.A.G workshop equipment catalogue t  Approved leak detection additive → V.A.G workshop equipment catalogue

t  Cleaning agent -VAS 6201/3--3- t  UV leak detector lamp -VAS 6201/4--4- t  UV-absorbing safety goggles -VAS 6201/6--5- t  Sticker -VAS 6201/7--6- –  Affix a sticker next to the service connections to indicate that UV leak detection additive has been added to this refrigerant circuit. –  Start up the air conditioner.   Note t  The air conditioner must be operated for at least 60 min. to distribute the additive throughout the refrigerant circuit (the air conditioner compressor must run). Depending on the extent of the leak, the leakage location may already become visible under UV light within this period. t  Depending on its magnitude and location, it may now take several days for sufficient refrigeration oil with UV leak detection additive to emerge to clearly localise the leakage point. –  Use a UV lamp VAS 6196/4 to locate the refrigerant circuit leak → Anchor. Adding UV leak detection additive to the refrigerant circuit using the leak detection system -VAS 6201- Special tools and workshop equipment required t  Leak detection system -VAS 6201-

The leak detection system VAS 6201 includes the following tools → V.A.G workshop equipment catalogue 1 -  Hand pump with low-pressure service hose, service coupling and non-return valve -VAS 6201/1- 2 -  Cartridge -VAS 6201/2- (with UV leak detection additive) 3 -  Cleaning solution -VAS 6201/3- 4 -  UV leak detection lamp -VAS 6201/4- 5 -  UV-absorbing eye protection -VAS 6201/6- 6 -  Sticker -VAS 6201/7- 7 -  TubeVAS 6201/8 8 -  Protective gloves -VAS 6201/9-   Note t  The following procedure describes the addition of UV leak detection additive using the hand pump -VAS 6201-. Heed the corresponding operating instructions if the UV leak detection additive is to be added to the refrigerant circuit using a different tool (e.g. an air conditioner service station). t  Indicated in the following is the quantity of UV leak detection additive to be added to a refrigerant circuit with a refrigeration oil quantity of 100 to 150 cm3 using the hand pump -VAS 6201- (2.5 +/- 0.5 cm3). If the quantity of refrigeration oil in the refrigerant circuit is greater, correspondingly more UV leak detection additive must be added (e.g. .5.0 +/- 0.5 cm3 for a refrigerant circuit with a refrigeration oil quantity of 250 cm3. For the corresponding refrigeration oil quantity in the refrigerant circuit, refer to → Chapter. t  Heed the quantity of UV leak detection additive given in the corresponding operating instructions if the UV leak detection additive is to be added to the refrigerant circuit using a different tool (e.g. an air conditioner service station).

Adding UV leak detection additive with refrigerant circuit empty The cartridge -A- contains 15.4 ml of UV leak detection additive (one unit -B- corresponds to 2.5 ml).

–  Assemble the hand pump -VAS 6201-, item -1- with the cartridge, item -2--VAS 6201/2-. –  Insert filler tube -VAS 6201/8- ( → Anchor item -7-) in hand pump. –  Open hand pump service valve.   Note t  When the refrigerant circuit is empty, the UV leak detection additive can be added to the circuit via a service connection or an open connection. t  If the refrigerant circuit is empty, it may be better to add the UV leak detection additive by way of a joint (e.g. if a joint has already been unfastened). In this way, no UV leak detection additive is left in the service connection and the connection does not have to be cleaned. t  Addition of UV leak detection additive to the refrigerant circuit by way of a service connection → Anchor. t  Addition of UV leak detection additive to the refrigerant circuit by way of an open connection → Anchor.

Addition of UV leak detection additive to the refrigerant circuit by way of an open connection. –  Open the refrigerant circuit at a readily accessible connection. –  Cover the surrounding area with sheeting or absorbent paper. –  Hold filler tube upwards. –  Screw in the toggle of the hand pump until the UV leak detection additive emerges from the tube. –  Add 2.5 +/- 0.5 ml (millilitre = cm3) of UV leak detection additive to the refrigerant circuit (for a refrigerant circuit with a refrigeration oil quantity of 100 to 150 cm3).   Note Observe the following if UV leak detection fluid has already been poured into a refrigerant circuit in the course of previous repair work: Only add new UV leak detection fluid if refrigerant oil is renewed. If only a certain amount of refrigeration oil has been renewed, just add the corresponding quantity of UV leak detection additive. After renewing 100 ml of refrigeration oil on a vehicle containing 250 ml for example, just add 2 ml (cm3) of UV leak detection additive. –  Renew O-ring at open connection. –  Assemble refrigerant circuit. –  Affix a sticker next to the service connections to indicate that leak detection fluid has been added to this refrigerant circuit. –  Evacuate and charge the refrigerant circuit as specified → Chapter and → Chapter. –  Start up the air conditioner.   Note t  The air conditioner must be operated for at least 60 min. to distribute the additive throughout the refrigerant circuit (the air conditioner compressor must run). Depending on the extent of the leak, the leakage location may already become visible under UV light within this period. t  Depending on its magnitude and location, it may now take several days for sufficient refrigerant oil with additive to emerge to clearly localise the leakage point. –  Use a UV lamp VAS 6196/4 to locate the refrigerant circuit leak → Anchor. Adding UV leak detection additive with refrigerant circuit charged   Note t  Observe the following if leak detection fluid has already been poured into a refrigerant circuit in the course of previous repair work: Only add new leak detection fluid if refrigerant oil is renewed. If only a certain amount of refrigeration oil has been renewed, just add the corresponding quantity of leak detection fluid. After renewing 100 ml of refrigeration oil on a vehicle containing 250 ml for example, just add 1 ml (cm3) of UV leak detection additive. t  A small quantity of UV leak detection additive remains in the service connection. This is to be carefully removed so as to avoid subsequent erroneous leak detection.

The cartridge -A- contains 15.4 ml of UV leak detection additive (one unit -B- corresponds to 2.5 ml).

–  Switch off ignition. –  Detach cap from service connection on low-pressure end of refrigerant circuit. –  Assemble the hand pump -VAS 6201-, item -1- with the cartridge, item -2--VAS 6201/2-. –  Insert the tube -VAS 6201/8- ( → Anchor item -7-) in the service coupling and open the service coupling by screwing in the handwheel. Hold the hose upwards and screw in the toggle of the hand pump until the UV leak detection additive starts to emerge from the tube.   Note Make sure hand pump hose is completely filled with refrigerant. –  Close service coupling and remove filler tube from locking mechanism.

–  Cover the area around the service connection on the vehicle with sheeting or absorbent paper. –  Connect the filler unit to the refrigerant circuit service connection on the vehicle. –  Open the service connection by screwing in the handwheel. –  By screwing in the toggle of the hand pump, add 2.5 +/- 0.5 ml (millilitre = cm3) of UV leak detection additive to the refrigerant circuit (for a refrigerant circuit with a refrigeration oil quantity of 100 to 150 cm3).

–  Detach the filler unit from the service connection. –  Use absorbent paper, for example, to remove the residual UV leak detection additive from the service connection. –  Seal the service connection with the cap. –  If necessary, use cleaning solution to clean area around service connection. –  Affix a sticker next to the service connections to indicate that leak detection fluid has been added to this refrigerant circuit. –  Start up the air conditioner.   Note t  The air conditioner must be operated for at least 60 min. to distribute the additive throughout the refrigerant circuit (the air conditioner compressor must run). Depending on the extent of the leak, the leakage location may already become visible under UV light within this period. t  Depending on its magnitude and location, it may now take several days for sufficient refrigerant oil with additive to emerge to clearly localise the leakage point. –  Use a UV lamp VAS 6196/4 to locate the refrigerant circuit leak → Anchor. Locating refrigerant circuit leaks with UV lamp VAS 6196/4   WARNING Never look into the UV lamp. Never point the UV lamp at other people.   Note t  After adding the UV leak detection additive, the air conditioner must be operated for at least 60 min. to distribute the additive throughout the refrigerant circuit (the air conditioner compressor must run). Depending on the extent of the leak, the leakage location may already become visible under UV light within this period. t  Depending on its magnitude and location, it may take several days for sufficient refrigerant oil with additive to emerge to clearly localise the leakage point. t  In the event of leaks at the evaporator, the additive may be washed out with the condensate and emerge via the condensate drain. As considerable work is required on most vehicles to gain access to the evaporator, a check at the condensate drain for example can provide an indication of evaporator leakage. This does however require the additive to have been in the refrigerant circuit for a lengthy period (several days). t  The safety goggles are not only designed to provide eye protection. They also make the UV leak detection additive more readily visible under UV light. t  Depending on the accessibility of various parts of the refrigerant circuit, it may be necessary to remove certain vehicle components (e.g. the bumper or air cleaner). t  Certain parts of the refrigerant circuit are only supplied with a small quantity of refrigerant oil in the course of air conditioner operation (e.g. top-mounted cap of receiver attached to condenser on Audi A8 2010 >). In the event of leakage at such locations, it may take longer for a sufficient amount of refrigerant with refrigerant oil and additive which shows up under ultraviolet light to emerge for leak detection. In such areas it may therefore be appropriate to use an electronic leak detector for leak localisation → Chapter „Tracing refrigerant circuit leaks with electronic leak detector (e.g. V.A.G 1796)“.

–  Move the vehicle to a poorly lit area of the workshop (daylight or bright artificial lighting diminishes the effect of the UV light). –  Check the accessibility of the various parts of the refrigerant circuit and remove any components in the surrounding area which prevent a clear view of the refrigerant circuit components (e.g. noise insulation and bumper). –  Wear safety goggles to protect the eyes. –  Connect the UV lamp to a 12 V battery (vehicle battery). Take care to ensure correct polarity of connections. –  Switch on the UV lamp and illuminate the components of the refrigerant circuit. Locations at which leakage has resulted in the emergence of refrigerant, refrigeration oil and thus also UV leak detection additive show up under UV light (fluorescent).