Audi A8 1994 - Page 156

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not displayed in the measured values block (only on vehicles
with OBD “A/C System“). Refer to ⇒ Heating, Ventilation and
Air Conditioning; Rep. Gr. 87 ; Diagnosis and Testing or “Gui‐
ded Fault Finding“ using the Vehicle Diagnosis, Testing &
Information System -VAS5051B- .
Note
♦ For all complaints marked *, refer to
⇒ “4.4 Pressures, Checking“, page 153 .
♦ If a malfunction occurs at only one evaporator in vehicles with
two evaporators, also check pressures in the refrigerant cir‐
cuit.
♦ Observe test requirements. Refer to
⇒ “4.3 Refrigerant Circuit Concerns“, page 151 .
♦ Total cooling system failure.*
♦ Insufficient cooling performance at all vehicles speeds or en‐
gine speeds.*
♦ None or insufficient cooling after driving a few miles.* *
♦ No cooling or insufficient cooling at one or both evaporator(s)
(on vehicles with two evaporators).* *
♦ Compressor, A/C clutch -N25- or A/C compressor regulator
valve -N280- shut off by pressure switch (e.g. -F73-, -F118-, -
F129- -F129- or by A/C Control Head -E87- or Climatronic
Control Module -J255- ) due to excessive or inadequate pres‐
sure. *
♦ None or sharp decrease in fresh-air supply after driving sev‐
eral miles (evaporator iced up).* *
From these, the following complaints may also occur:
The A/C Compressor Makes Noises
– Tighten compressor securing bolts and compressor bracket
using a torque wrench.
– Check routing of refrigerant pipes; they must not touch other
components and must not be subject to strain (align if neces‐
sary).
Noise (Refrigerant Hammer) Occurring Immediately After Switch‐
ing On Air Conditioner And/Or When Cornering Or Braking
– Discharge, evacuate and charge refrigerant circuit (too much
refrigerant in circuit).
Note
Too much refrigerant oil in the circuit could also cause this prob‐
lem. This could occur if the amount of refrigerant oil was not
adjusted when replacing the A/C compressor.
Water Sprays Out Of Vents (In Dash Panel Or Footwell) Although
Air Conditioning System Is Otherwise Functioning Properly
– Check proper routing of condensate drain; it must not be
crushed or kinked.
– Check condensation drain valve, it must not be clogged by wax
or underbody sealant and must close properly.
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
152 Rep. Gr.00 - General, Technical Data