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Checking systems with an expansion valve and receiver (with internally regulated air conditioner compressor) > < Checking systems with a restrictor and reservoir (with internally regulated air conditioning system compressor)

Leon Mk2

Specifications:
Specifications:
High-pressure side:
From initial pressure (upon connecting the manometer) increasing to a maximum of 20 bar positive pressure.
Low-pressure side:
   
From initial pressure (upon connecting the manometer) decreasing to the diagram value.
A - High pressure (measured at the service connection) in bar positive pressure.
B - Low pressure (measured at the connection with the valve at the air conditioner compressor or at the reservoir) in bar positive pressure.
C - Permitted tolerance range.
D - Low pressure (measured at the connection with the valve for the low-pressure switch or at the service connection) in bar positive pressure.
E - Permitted tolerance range.
  A87-0006
Possible deviation from specification Possible cause of faultRectifying fault
l  High pressure remains constant or increases only slightly (above the pressure measured when the engine is stopped),
l  Low pressure falls quickly to the diagram value or lower,
l  the required cooling power is not delivered.
Too little refrigerant in circuit.
–  Look for leaks using leak detector and rectify them.
–  Recharge refrigerant circuit.
l  High pressure normal,
l  Low pressure matches the diagram value,
l  the required cooling power is not delivered.
  
l  High pressure normal,
l  Low pressure is too low (see diagram),
l  the required cooling power is not delivered.
  

  Note!
If no fault can be found for this complaint, flush refrigerant circuit with compressed air and nitrogen.
   
Possible deviation from specification Possible cause of faultRectifying fault
l  High pressure increases only slightly above the pressure measured when the engine is stopped,
l  Low pressure falls only slightly,
l  the required cooling power is not delivered.
The air conditioner compressor is defective.
–  Rinse (clean) refrigerant circuit → Chapter.
–  Renew air conditioner compressor.

   
Possible deviation from specificationPossible cause of faultRectifying fault
l  High pressure increases beyond the specification,
l  Low pressure falls quickly to the diagram value or lower,
l  the required cooling power is not delivered.
Restriction or obstruction in the refrigerant circuit.
–  Feel the refrigerant circuit with the hand to sense the temperature gradient.
l  At one component a temperature gradient will be detected:
–  If a hose or pipe is kinked or crushed, renew it.
–  In case of an obstruction, flush refrigerant circuit with compressed air and nitrogen.
l  If no faults are found:
–  Rinse (clean) refrigerant circuit → Chapter.
l  High pressure and low pressure are normal at first, but after a time,
l  the high pressure increases beyond the specified value,
l  the low pressure falls to the diagram value or lower,
l  the cooling power called for is not delivered.
Moisture in the refrigerant circuit.
–  Flush refrigerant circuit with compressed air and nitrogen.
–  Renew receiver.
–  Repeat the check; if the system does not operate correctly
–  Rinse (clean) refrigerant circuit → Chapter.
–  Recharge refrigerant circuit.
–  Repeat check.
l  High pressure normal,
l  Low pressure is too low (see diagram),
l  the cooling power called for is delivered.
The air conditioner compressor is defective.
–  Rinse (clean) refrigerant circuit → Chapter.
–  Renew air conditioner compressor.

  Note!
t  If the fault is “high pressure normal, low pressure too low ” please note the following:
t  In this case, the evaporator may be iced up or the low-pressure switch for air conditioning system -F73- has switched off the air conditioning system compressor, although the correct quantity of refrigerant is present in the refrigerant circuit.
   
Possible deviation from specification Possible cause of faultRectifying fault
l  High pressure normal or too high,
l  Low pressure too high (see diagram),
l  The air conditioner compressor is noisy (especially immediately after being switched on),
l  the required cooling power is not delivered.
Too much refrigerant in circuit.
–  Extract some refrigerant from the refrigerant circuit.
l  The quantity of refrigerant extracted is about equal to the prescribed charge quantity.
–  Renew the air conditioning system compressor.
l  The quantity of refrigerant extracted is significantly greater than the prescribed charge quantity.
–  Recharge refrigerant circuit.
–  Repeat check.

  Note!
Overfilling with refrigerant oil can occur if the refrigerant oil level was not checked after the air conditioner compressor was renewed.
   

Checking systems with an expansion valve and receiver (with internally regulated air conditioner compressor) > < Checking systems with a restrictor and reservoir (with internally regulated air conditioning system compressor)