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Volkswagen Workshop Service and Repair Manuals

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Verification for vehicles with expansion valve and liquid loop / dryer (air conditioning compressor with internal adjustment dev > < Verification for vehicles with butterfly (throttle) and collection tank (air conditioning compressor with internal adjustment de

Polo Mk4

Nominal values
Nominal values
High pressure side:
Gradual rise from outlet pressure (at the time of connecting the pressure gauge) up to a maximum pressure of 20 bar.
Low pressure side:
   
Gradual fall of the outlet pressure (at the time of connecting the pressure gauge) to the value given in the diagram.
A - High pressure (measured at the service terminal), expressed in overpressure bar.
B - Low pressure (measured at the valve terminal next to the air conditioning compressor or collection tank), expressed in overpressure bar.
C - Admissible tolerance limit.
D - Low pressure (measured at the valve terminal next to the low pressure switch or the service terminal), expressed in overpressure bar.
E - Admissible tolerance limit.
  A87-0006
Admissible deviation from the nominal valuePossible cause of the faultTroubleshooting
l  High pressure remains constant or rises only marginally above the value measured with the engine stopped.
l  Low pressure decreases rapidly to the value given in the diagram or below it.
l  The desired cooling power is not reached.
t  The amount of refrigerant gas in the loop is too small.
–  Suck refrigerant gas from the circuit → Chapter
l  The quantity of refrigerant gas sucked is significantly less than the filling capacity indicated.
–  Locate and eliminate the leak → Chapter.
–  Refill the refrigerant gas loop → Chapter.
l  High pressure is normal.
l  Low pressure matches the value given in the diagram.
l  The desired cooling power is not reached.
  
l  High pressure is normal.
l  Low pressure is very low (see diagram).
l  The desired cooling power is not reached.
  

  Note
If no fault is found, vent the refrigerant gas loop → Chapter.
   
Admissible deviation from the nominal valuePossible cause of the faultTroubleshooting
l  High pressure rises only marginally above the value measured with the engine stopped.
l  Low pressure decreases only marginally.
l  The desired cooling power is not reached.
t  The air conditioning compressor is damaged.
–  Wash the cooling refrigerant loop (clean) → Chapter.
–  Replace the air conditioning compressor.
l  High pressure rises above the nominal value.
l  Low pressure decreases rapidly to the value given in the diagram or below it.
l  The desired cooling power is not reached.
t  Bottle neck or obstruction in the refrigerant gas loop.
–  Check manually whether the refrigerant gas has temperature gradients.
l  A temperature gradient was detected in one of the components:
–  Replace the component if one of its rigid or flexible tubes is either folded or bottle necked.
–  In case of obstruction, vent the refrigerant gas loop → Chapter.
–  Refill the refrigerant gas loop → Chapter.
–  Check again.
l  No fault was detected:
–  Check again.
l  High and low pressure show normal values initially.
l  After some time, the high pressure rises above the nominal values.
l  Low pressure decreases rapidly to the value given in the diagram or below it.
l  The desired cooling power is not reached.
t  Humidity in the refrigerant gas loop.
–  Vent the refrigerant gas circuit → Chapter.
–  Replace the collection tank.
–  Recheck in case of malfunction.
–  Refill the refrigerant gas loop → Chapter.
–  Check again.
l  High pressure is normal.
l  Low pressure is very low (see diagram).
l  The desired cooling power is not reached.
t  The air conditioning compressor is damaged.
–  Replace the air conditioning compressor → Heating, air conditioning; Rep. Gr.87.

  Note
t  If a fault is detected “with high pressure normal, low pressure very low”, please observe the following:
t  With this fault, the evaporator may freeze or the Air conditioning low pressure switch -F73- may turn off the air conditioning compressor even though the refrigerant gas amount contained in the loop is OK.
   
Admissible deviation from the nominal valuePossible cause of the faultTroubleshooting
l  High pressure is normal or very high.
l  Low pressure is very high (see diagram).
l  The air conditioning compressor is noisy (especially after starting).
l  The desired cooling power is not reached.
t  There is too much refrigerant gas in the loop.
–  Suck refrigerant gas from the loop → Chapter.
l  The quantity of refrigerant gas sucked more or less matches the filling capacity indicated.
–  Replace the air conditioning compressor.
l  The quantity of refrigerant gas sucked is significantly greater than the filling capacity indicated.
–  Refill the refrigerant gas loop → Chapter.
–  Check again.

   

Verification for vehicles with expansion valve and liquid loop / dryer (air conditioning compressor with internal adjustment dev > < Verification for vehicles with butterfly (throttle) and collection tank (air conditioning compressor with internal adjustment de