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Note
♦
If the display pressure does not change and the A/C compres‐
sor activation is OK, then see if the A/C compressor is actually
being driven. If the A/C compressor is being driven, then the
fault is in the refrigerant circuit. Bring vehicle to a workshop
that has the necessary tools and in which the work can be
performed accordingly by qualified personnel. Refer to ⇒ Re‐
frigerant R134a Servicing; Rep. Gr. 00 ; General Information
(it is possible that A/C compressor regulation is not OK). Bring
the problems determined to the attention of the workshop.
♦
A/C Compressor Regulator Valve is activated by Climatronic
control module so that temperature of air downstream of evap‐
orator reaches the specified value (approximately 2 to 5 °C):
♦
A value greater than 75% (0,55A) is displayed after vehicle
start, depending on temperature, engine speed and vehicle
voltage measured. As soon as the temperature measured by
the evaporator vent temperature sensor -G263- nears the tar‐
get value, the activation, and thus the compressor output, is
reduced.
♦
Under certain operating conditions, moisture in the refrigerant
circuit can lead to ice build-up on the A/C compressor regulator
valve (and on the expansion valve). A/C compressor control
is reduced by this ice build-up, evaporator is cooled too in‐
tensely and freezes. The ice on the evaporator may cause
various customer concerns. Refer to
⇒ “4.2.5 Ice Formation on Evaporator, Localizing Malfunction“,
– Press recirculation button on Climatronic control module (sym‐
bol for “recirculating air mode“ lights up in
recirculation
button).
– Set engine speed of 2000 rpm (start of time measurement).
– In “read measured values block“, select the display with the
measured value from the evaporator vent temperature sensor
-G263- using -VAS5051B- under "Guided Fault Finding."
Audi TT 2007 ➤
Heating, Ventilation and Air Conditioning - Edition 01.2011
4. Diagnosis and Testing
83