Audi A4 2001 - Pressures, Checking

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– Check plenum chamber cover; it must not be damaged and
must be properly installed (to stop water running into evapo‐
rator).
– Check water drains in plenum chamber; they must not be
blocked (e.g. by leaves).
4.4 Pressures, Checking
⇒ “4.4.1 Checking Pressure with Service Station“, page 153
⇒ “4.4.2 Test Prerequisites“, page 154
⇒ “4.4.3 Pressures, Checking “, page 156
⇒ “4.4.4 Checking Pressures For Vehicles With Restrictor and
Accumulator - Internally Regulated Compressor“, page 159
⇒ “4.4.5 Specified Values For Vehicles With Restrictor and Ac‐
cumulator - Internally Regulated Compressor“, page 159
⇒ “4.4.6 Checking Pressures On Vehicles With Expansion Valve
and Fluid Reservoir - Internally Regulated Compressor“,
page 164
⇒ “4.4.7 Specified values Vehicles With Expansion Valve and
Fluid Reservoir - Internally Regulated Compressor“, page 165
⇒ “4.4.8 Checking Pressures On Vehicles with Restrictor, Res‐
ervoir and A/C Compressor Regulator Valve - Externally Regula‐
ted A/C Compressor“, page 171
⇒ “4.4.9 Specified Values On Vehicles with Restrictor, Reservoir
and A/C Compressor Regulator Valve - Externally Regulated A/
C Compressor“, page 171
⇒ “4.4.10 Checking Pressures On Vehicles with Restrictor, Ac‐
cumulator and A/C Compressor Regulator Valve - Externally
Regulated Compressor“, page 178
⇒ “4.4.11 Specified Values On Vehicles with Restrictor, Accumu‐
lator and A/C Compressor Regulator Valve - Externally Regulated
Compressor“, page 179
4.4.1 Checking Pressure with Service Station
Note
♦ All test conditions marked * are vehicle-specific and are de‐
scribed in the Repair Manual for the relevant vehicle.
♦ Check cooling performance.
♦ Connections with valve and service connections for measure‐
ment and testing, refer to ⇒ Heating, Ventilation and Air
Conditioning; Rep. Gr. 87 ; Diagnosis and Testing (vehicle-
specific repair manual).
♦ Depending on the A/C compressor version, there may be a
valve installed on the high pressure side of the A/C compres‐
sor, which prevents the liquid refrigerant from flowing back into
the compressor once the A/C is turned off. If an A/C compres‐
sor with this valve is installed in a vehicle with a refrigerant
circuit having an expansion valve, then it may take some time
until the pressure in the high pressure side decreases (the ex‐
pansion is cold and the pressure in the low pressure side
quickly increases after it is turned off, the expansion valve
closes and the refrigerant flows slowly into the low pressure
side). If the A/C compressor is switched on, the pressure on
the low pressure side goes down, the expansion valve open
and the refrigerant can flow of the low pressure side.
Audi 100 1991 ➤ , Audi 80 1992 ➤ , Audi A1 2011 ➤ , Audi A2 2001 ➤ , A ...
Refrigerant R134a Servicing - Edition 01.2011
4. Diagnosis and Testing 153