Audi A2 2001 - Page 180

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Possible deviation from spec‐
ification
Possible cause of fault Corrective action
• High and low pressure
normal at first, after some
time high pressure increa‐
ses above specification
• Low pressure quickly
drops to value in graph or
below,
• Required cooling output is
no longer attained.
♦ Actuation of A/C compressor reg‐
ulator valve -N280- malfunction‐
ing
♦ Moisture in refrigerant circuit
– Check the A/C compressor regulator
valve activation.
– Replace accumulator (with dryer)
and evacuate refrigerant circuit for at
least 3 hours (see note)
– Clean refrigerant circuit (flush with
refrigerant R134a, refer to
⇒ “1.4.13 Refrigerant Circuit Flush‐
ing With Refrigerant R134a“,
page 32 or blow through with com‐
pressed air and nitrogen, refer to
⇒ “1.4.12 Refrigerant Circuit Flush‐
ing With Compressed Air and Nitro‐
gen “, page 29 )
• High and low pressure
normal at first
• After lengthy operating pe‐
riod, low pressure drops
excessively (evaporator
ices up)
Note
♦ It is not initially necessary to clean the refrigerant circuit (flush
using refrigerant R134a, refer to
⇒ “1.4.13 Refrigerant Circuit Flushing With Refrigerant
R134a“, page 32 or blow through using compressed air and
nitrogen, refer to
⇒ “1.4.12 Refrigerant Circuit Flushing With Compressed Air
and Nitrogen “, page 29 ) when this problem occurs since nor‐
mally there is only a small quantity of moisture in the system
which can be removed by lengthy evacuation.
♦ If problem involving moisture in refrigerant circuit only occurs
after a lengthy operating period or only infrequently (low pres‐
sure drops below specification and evaporator ices up), it is
sufficient to replace the dryer (adjust quantity of refrigerant oil).
Refrigerant circuit is then to be evacuated for at least 3 hours.
♦ Problem with Evaporator Vent Temperature Sensor -G263-
can also cause icing-up of refrigerant circuit. If this problem is
encountered, also pay attention to measured value of evapo‐
rator vent temperature sensor using Vehicle Diagnosis, Test‐
ing & Information System -VAS5051B- (“OBD“ or “Guided
Fault Finding for the A/C System“ and ⇒ Heating, Ventilation
and Air Conditioning; Rep. Gr. 87 ; Diagnosis and Testing
(vehicle-specific repair manual).
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
176 Rep. Gr.00 - General, Technical Data