Audi A2 2001 - Page 177

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Note
♦ If high cooling output is needed (for example, the outside tem‐
perature is very high, the blower speed is set on high but the
engine RPMs are low), then the A/C compressor will not bring
the pressure on the low pressure side to the value specified in
the diagram -C- (for example, for a certain time after turning
on the A/C). Compressor is actuated with maximum specified
control current, however delivery volume is no longer sufficient
at this engine speed to reduce pressure on low-pressure side
to value in graph. To check the A/C compressor control under
these conditions, for example, the fresh air blower is controlled
only with approximately 40% of the maximum voltage, check
the pressures at a lower fresh air blower speed using Vehicle
Diagnosis, Testing & 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).
♦ Under unfavorable conditions (very high ambient tempera‐
tures, high humidity), pressure on high-pressure side may
increase to maximum 29 bar.
♦ Control current -B- is displayed in measured value block of
Front A/C display control head -E87- or Climatronic Control
Module -J255- .
♦ The measured pressure from the High pressure sensor -G65-
or from the A/C pressure/temperature sensor -G395- inside
the refrigerant circuit pressure is displayed in the measured
values block for the Front A/C display control head -E87- and
the Climatronic control module -J255- . Check using Vehicle
Diagnosis, Testing & 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).
♦ Low pressure settles as a function of control current for A/C
compressor regulator valve -N280- within compressor output
range in tolerance range.
♦ Under unfavorable conditions (very high ambient tempera‐
tures, high humidity), compressor output may not always be
sufficient to attain the specified value.
♦ If compressor capacity utilization is greater than 90%, pres‐
sure on low-pressure side may be in excess of tolerance range
“C“ shown in graph (compressor output no longer sufficient).
♦ The specified operating current for the regulator valve must be
greater than 0.3 A in order to ensure reliable valve activation.
♦ At absolute pressure, 0 bar corresponds to absolute vacuum.
Normal ambient pressure corresponds to 1 bar absolute pres‐
sure. 0 bar pressure corresponds to an absolute pressure of
one bar on most pressure gauges (indicated by -1 bar below
0).
♦ In "maximum cooling output" setting , control current is regu‐
lated to approximately 0.65 (vehicle-specific up to 0.85A, dis‐
played in measured value block) using Vehicle Diagnosis,
Testing & 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 or
⇒ A/C System; Rep. Gr. 87 (vehicle-specific repair manual).
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
4. Diagnosis and Testing 173