Audi Q5 2008 - 5.2 Leaking or Damaged Components Except A;C Compressor, Accumulator or Receiver - Circuit Contains Refrigerant; 5.3 Compressor, Replacing Without Flushing Refrigerant Circuit

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Note
♦ This fault may also be caused by too much refrigerant oil in
the circuit. Overfilling with refrigerant oil can occur if, for ex‐
ample, the compressor has been replaced without adjusting
the quantity of refrigerant oil.
♦ 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 however refrigerant cannot flow via expan‐
sion valve, cooling output is not attained, high pressure may
also not increase or only increase slightly due to the absence
of energy. Check using Vehicle Diagnosis, Testing & Informa‐
tion System -VAS5051B- (“OBD“ or “Guided Fault Finding for
the A/C System“) and ⇒ Heating, Ventilation and Air Condi‐
tioning; Rep. Gr. 87 ; Diagnosis and Testing (vehicle-specific
repair manual).
Possible deviation from speci‐
fication
Possible cause of fault Corrective action
• High and low pressure nor‐
mal
• The required cooling per‐
formance is obtained
♦ Actuation of A/C compressor regulator
valve -N280- malfunctioning
♦ To much refrigerant in the circuit.
♦ Expansion valve malfunctioning
– Check the A/C compressor
regulator valve activation.
– Discharge refrigerant circuit
– Clean refrigerant circuit
(flush with refrigerant R134a,
refer to
⇒ “1.4.13 Refrigerant Circuit
Flushing With Refrigerant
R134a“, page 32 or blow
through with compressed air
and nitrogen, refer to
⇒ “1.4.12 Refrigerant Circuit
Flushing With Compressed
Air and Nitrogen “, page 29 ).
• High and low pressure nor‐
mal
• A/C compressor noise (par‐
ticularly after switch-on)
• The required cooling per‐
formance is obtained
– Fill in correct quantity of re‐
frigerant oil into circuit (see
note).
– Charge the refrigerant circuit
– Repeat test, if function is not
OK:
– Replace expansion valve
– Charge the refrigerant circuit
– Repeat test
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
4. Diagnosis and Testing 189