Audi A2 2001 - Page 187

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Note
♦ If no fault is found with this complaint, clean 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 ).
♦ Check the measured values from the Evaporator vent tem‐
perature sensor -G263- and the A/C compressor regulator
valve control. If measured value of Evaporator vent tempera‐
ture sensor is not OK, evaporator may ice up or cooling output
is not attained.
♦ If air conditioner operation is not OK when test is repeated after
replacing expansion valve, install old expansion valve, clean
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 ). Then replace A/C compressor and
reservoir.
♦ With this malfunction, evaporator may ice up although quantity
of refrigerant in circuit is OK.
♦ If expansion valve is malfunctioning (permanently closed or
does not open sufficiently), A/C compressor regulator valve is
actuated to maximum output and low pressure drops to value
in graph or below (compressor draws off refrigerant from low-
pressure side). As refrigerant cannot flow via expansion valve,
cooling output is not attained, high pressure may also not in‐
crease or only increase slightly due to the absence of energy.
Check using Vehicle Diagnosis, Testing & Information System
-VAS5051B- (“OBD“ or “Guided Fault Finding for the A/C Sys‐
tem“) and ⇒ Heating, Ventilation and Air Conditioning; Rep.
Gr. 87 ; Diagnosis and Testing (vehicle-specific repair man‐
ual).
Possible devia‐
tion from specifi‐
cation
Possible cause of
fault
Corrective action
• High pres‐
sure does not
increase or
only increa‐
ses slightly
above pres‐
sure with en‐
gine stopped.
• Low pressure
does not drop
or drops only
slightly.
• Required
cooling out‐
put is not at‐
tained
♦ The A/C com‐
pressor is not ac‐
tivated ( A/C com‐
pressor regulator
valve -N280- )
♦ The A/C com‐
pressor is not be‐
ing driven.
– Check the A/C
compressor drive.
Refer to ⇒ Heating,
Ventilation and Air
Conditioning; Rep.
Gr. 87 ; Diagnosis
and Testing .
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
4. Diagnosis and Testing 183