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Verification for vehicles with butterfly (throttle) and collection tank (air conditioning compressor with internal adjustment de > < Checking pressure values in the refrigerant gas loop

Polo Mk4

Checking pressure values
Checking pressure values
–  Turn off the ignition and all electrical components.
–  Connect the Climate control recovery, recycling and refill set or EQ 7098 -VAS 6008- → Chapter.
–  Read the pressure gauges.
Pressures and temperatures recorded in the refrigerant gas loop vary depending on operational conditions (for example, engine speed, refrigerant liquid fan speed, engine temperature, compressor on or off) and on environmental factors (such as ambient temperature, humidity and requested cooling power).
In vehicles with Adjustment valve for the air conditioning compressor -N280-, the pressure on the low pressure side changes with the operation of the valve.
For this reason, the values in the table should only be considered as a reference. These values are reached after 20 minutes, at an engine speed of between 1,500 and 2,000 rpm and at ambient temperature of 20 ºC.
   
Ambient temperature (in degrees Celsius)Refrigerant gas circuit pressure in overpressure bar
+15 °C3,9
+20 °C4,7
+25 °C5,6
+30 °C6,7
+35 °C7,8
+40 °C9,1
+45 °C10,5

  Note
t  The temperature of the components of the refrigerant gas loop must be equal to the ambient temperature.
t  If some assembly components of the refrigerant gas loop should be hotter or colder, the pressure will not match the values given in the table.
t  When pressure is expressed as absolute pressure, 0 (zero) bar corresponds to an absolute vacuum. Normal atmospheric pressure (overpressure) is equal to 1 (one) bar of absolute pressure. On most pressure gauge scales, 0 (zero) bar equals 1 (one) bar of absolute pressure (identifiable by the indication (-1) below the (0)).
t  In vehicles equipped with a High pressure sensor -G65- in which the pressure measured is indicated in the measurement values block, the value must match the values given in the table.
If the pressure in the refrigerant gas loop is less than the value given in the table:
The amount of refrigerant gas in the loop is too small.
–  Detect leaks in the refrigerant gas loop → Chapter.
–  Check the overpressure relief valve.
If the overpressure relief valve has released pressure:
–  Check activation of the radiator fan.
–  Check the refrigerant gas lines for bottle necks and small twists.
–  Check the refrigerant gas lines for external damage.
–  If no damage is found, vent the refrigerant gas loop.
If the pressure in the refrigerant gas loop is equal to or greater than the value given in the table:
–  Start the engine.
–  In the air conditioning temperature adjustment mechanism, select the lowest temperature (maximum cooling power).
  Note
If the low pressure switch has been disassembled in order to connect the Climate control recovery, recycling and refill set or EQ 7098 -VAS 6008-, bridge the electric terminals of the respective connector.
l  The air conditioning compressor is activated by the engine, via the Air conditioning magnetic coupler -N25-.
l  The Adjustment valve for the air conditioning compressor -N280- is activated by the Climatronic control unit -J255-.
If the compressor or the adjustment valve do not operate with the engine running:
–  Detect and eliminate the cause of the fault by checking, for example, the air conditioning fault memory → Vehicle diagnosis, testing and information system VAS 5051.
–  Observe checking conditions → Chapter.
–  Check the power supply to the Air conditioning magnetic coupler -N25-; if it is in order, repair the Air conditioning magnetic coupler -N25-. Refer to the specific repair manual for each vehicle → Heating, air conditioning; Rep. Gr.87.
–  Check the activation of the Adjustment valve for the air conditioning compressor -N280-.
Continuation of pressure value checking:
t  Vehicles with butterfly (throttle) and collection tank (air conditioning compressor with internal adjustment device) → Chapter.
t  Vehicles with expansion valve and liquid tank / dryer (air conditioning compressor with internal adjustment device) → Chapter.
t  Vehicles with expansion valve, liquid tank / dryer and Adjustment valve for the air conditioning compressor -N280- (air conditioning compressor with external adjustment device) → Chapter.
t  Vehicles with butterfly (throttle), collection tank and regulating valve for the air conditioning compressor -N280- (air conditioning compressor with external adjustment device) → Chapter .
   

Verification for vehicles with butterfly (throttle) and collection tank (air conditioning compressor with internal adjustment de > < Checking pressure values in the refrigerant gas loop