SEAT Workshop Service and Repair Manuals

Specifications: High-pressure side: Increasing by a maximum of 20 bars from the initial pressure (when connecting the manometers). Low-pressure side:

Decreasing to the value of the diagram from the initial pressure (when connecting the manometers). A -  High pressure in bar positive pressure. B -  Low pressure in bar positive pressure. C -  Permitted tolerance range.

Possible deviation from specification	Possible cause of fault	Measures to be taken
l  High pressure remains constant or increases only slightly (above the pressure measured when the engine is stopped), l  The low pressure falls to the diagram value or lower, l  Required cooling output is not attained	Too little refrigerant in circuit or expansion valve defective.	–  Extract some refrigerant from the refrigerant circuit. l  If quantity of refrigerant extracted roughly corresponds to actual capacity: –  Renew the expansion valve. –  Recharge refrigerant circuit. –  Repeat the check.
l  High pressure is normal, l  Low pressure matches the diagram value, l  Required cooling output is not attained		l  If quantity of refrigerant extracted is substantially less than specified capacity: –  Find leak with leak detector and eliminate. –  Recharge refrigerant circuit. –  Repeat the check.

If no fault can be found and air conditioner operation is not OK when test is repeated, clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen ).

Possible deviation from specification	Possible cause of fault	How to rectify fault
l  High pressure rises above specification, l  The low pressure falls to the diagram value or lower, l  Required cooling output is not attained	t  Restriction or obstruction in the refrigerant circuit. t  Expansion valve defective.	–  Feel AC circuit with hand to determine temperature differences. l  If temperature differences are perceptible on a component: –  Renew hose or pipe if kinked or constricted. –  In the event of clogging, clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen and renew expansion valve if applicable). l  If no fault is found. –  Clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen and renew expansion valve if applicable). –  Repeat the check.

If, after cleaning (flushing with R134a refrigerant or blowing out with compressed air or nitrogen) the AC circuit still does not operate properly, replace the expansion valve.

Possible deviation from specification	Possible cause of fault	Measures to be taken
l  High and low pressure normal at first l  after a time the high-pressure increases beyond the specified value, the low-pressure falls to the diagram value or lower, l  Required cooling output is not attained	t  Expansion valve defective. t  Moisture in the refrigerant circuit.	–  Inspect the expansion valve. Replace if any dirt or corrosion is found. –  Blow through refrigerant circuit with compressed air and nitrogen. –  Replace the collecting tank. –  Repeat the check. If operation is not correct: –  Flush the refrigerant circuit (clean) –  Recharge refrigerant circuit. –  Repeat check.
l  High and low pressure normal at first l  After lengthy operating period, low pressure drops excessively (evaporator ices up)

Always replace the liquid tank when this fault occurs.

Possible deviation from specification	Possible cause of fault	How to rectify fault
l  High pressure normal or too high, l  Low pressure too high (see diagram), l  Required cooling output is not attained l  Compressor noise (particularly after switch-on)	t  Too much refrigerant in circuit. t  Expansion valve or compressor faulty.	–  Extract some refrigerant from the refrigerant circuit. l  If quantity of refrigerant extracted roughly corresponds to actual capacity: –  Renew the expansion valve. –  Recharge refrigerant circuit. –  Repeat the check. l  The quantity of refrigerant extracted is significantly greater than the prescribed charge quantity: –  Recharge refrigerant circuit. –  Repeat the check.

If operation of the air conditioning system is not OK when the test is repeated, re-fit old expansion valve and clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen ). Replace the compressor and liquid tank.

Possible deviation from specification	Possible cause of fault	Measures to be taken
l  High pressure increases only slightly above the pressure measured when the engine is stopped, l  Low pressure falls only slightly, l  Required cooling output is not attained	Compressor defective	–  Clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen ). –  Replace the compressor and liquid tank.

Possible deviation from specification	Possible cause of fault	Measures to be taken
l  High pressure is normal, l  Low pressure too low (see graph) l  Required cooling output is attained	Expansion valve or compressor faulty.	–  Renew the expansion valve. –  Recharge refrigerant circuit. –  Repeat the check.

t	If operation of the air conditioning system is not OK when the test is repeated, re-fit old expansion valve and clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen ). Replace the compressor and liquid tank.

t	When this fault occurs, it is possible for the evaporator to ice up even when the proper quantity of refrigerant is present in the circuit.

Possible deviation from specification	Possible cause of fault	Measures to be taken
l  High and low pressure normal l  Required cooling output is not attained	Too much refrigerant oil in the circuit.	–  Drain refrigerant circuit. –  Clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen ).
l  High and low pressure normal l  Compressor noise (particularly after switch-on) l  Required cooling output is attained

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

t	If there is too much refrigerant oil in the circuit, discharge compressor and renew receiver. After cleaning the refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen), add the correct amount of refrigerant oil to the circuit → Chapter.