Note
♦
After adding the leak detection additive, the A/C system must
be operated for a minimum of 60 min. so that the additive dis‐
tributes itself in the entire refrigerant circuit (compressor must
be running). Depending on the size of the leak, it may become
visible under UV light within that time.
♦
Depending on the size and location of the leak, it can now last
up to several days until enough refrigerant oil with additive
flows out to determine definitely the leaking area.
♦
With leaks on evaporator, leak detection additive is possibly
washed off with condensation and flows out via evaporator
drain. Since the evaporator is not easily accessible on most
vehicles, checking the evaporator drain may indicate if the
evaporator is leaking. However, it is necessary for this purpose
that leak detection additive has already been in the refrigerant
circuit for a long period of time (i.e. a few days).
♦
Protective goggles do not only serve as eye protection but also
amplify the illumination of leak detection additive under UV
light.
♦
Depending on the accessibility of different components in the
refrigerant circuit, it may be necessary to remove some vehicle
components such as the bumper or air filter.
♦
Only a little refrigerant oil will get onto certain places on the
refrigerant circuit when A/C is being used (for example, on the
top cover of the fluid reservoir attached to the condenser on
an Audi A8 from MY 10). If there is a leak at this spot, it may
take longer until enough refrigerant with refrigerant oil and ad‐
ditive start to leak out, which then can be viewed under UV
light. It may be useful to use an electronic leak detector at
these locations to find a leak. Refer to
⇒ “4.2.2 Refrigerant Circuit, Tracing Leaks Using Electronic
Leak Detector V.A.G 1796“, page 144 .
– Move vehicle into a slightly darker area of the workshop (with
daylight or bright lighting the effect of the UV light is diminish‐
ed).
– Check the accessibility of the various components in the re‐
frigerant circuit and remove any components in the area that
block access to the refrigerant circuit such as noise insulation
and the bumper.
– Wear protective eyewear to protect the eyes.
– Connect the UV-lamp to a 12 volt battery (vehicle battery).
Observe correct polarity of connections.
– Switch on UV lamp and illuminate components of refrigerant
circuit. Locations where refrigerant, refrigerant oil and leak de‐
tection additive has leaked out light up under fluorescent UV
light.
4.3 Refrigerant Circuit Concerns
• Electrical system, vacuum system and air duct fault-finding
has not revealed any faults. Refer to Guided Fault Finding for
the A/C system using Vehicle Diagnosis, Testing & Informa‐
tion System -VAS5051B- , ⇒ Wiring diagrams, Troubleshoot‐
ing & Component locations and ⇒ Heating, Ventilation and Air
Conditioning; Rep. Gr. 87 ; Diagnosis and Testing .
• The OBD/Guided Fault Finding for the A/C System with Vehi‐
cle Diagnosis, Testing & Information System -VAS5051B-
cannot detect a fault, the A/C compressor shut off condition is
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
4. Diagnosis and Testing 151
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