SEAT Workshop Service and Repair Manuals

Specifications: High-pressure side: Increasing by 20 bar 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 -  Low-pressure (measured at the service port) in bar absolute pressure. B -  Control current for air conditioner compressor regulating valve -N280- in amps C -  Permitted tolerance range.   Note t  Under unfavourable conditions (very high ambient temperatures, high air humidity), the pressure in the high-pressure side may increase up to a maximum of 29 bar. t  The control current -B- is indicated in the measured values block. t  The high pressure is indicated in the measured values block → Rep. gr.87. t  The low pressure is adjusted according to the control current for the air-conditioner compressor regulating valve -N280- within the tolerance margin in the compressor power range. t  Under unfavourable conditions (very high ambient temperatures, high air humidity), the power may not always be sufficient to reach the prescribed value. t  The set working current for the regulating valve must be greater than 0.3 A to ensure that the regulating valve is reliably activated. t  At the setting for „maximum cooling power“, the control current should be approx. 0.8 A (indicated in the measured values block) → Rep. gr.87. t  Absolute pressure means that 0 bar corresponds to an absolute vacuum. The normal ambient pressure corresponds to 1 bar absolute pressure. In general, most manometer scales represent atmospheric pressure as 0 bar, meaning an absolute pressure of 1 bar (this can be recognized if there is a -1 on the scale).

Possible deviation from specification	Possible cause of fault	How to rectify fault
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	t  The control for the AC compressor regulating valve -N280- is defective. t  Insufficient refrigerant in circuit.	–  Check control for AC compressor regulating valve -N280-. –  Find leak with leak detector and eliminate. –  Recharge refrigerant circuit.
l  High pressure is normal, l  Low pressure too low (see graph) l  Required cooling output is not attained
l  High pressure is normal, l  Low pressure too low (see graph) l  Required cooling output is not attained

Clean the refrigerant circuit (rinse with refrigerant R134a or sweep with compressed air or nitrogen).

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	t  The control for the AC compressor regulating valve -N280- is defective. t  Compressor defective	–  Check control for AC compressor regulating valve -N280-. –  Clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen ). –  Renew compressor.
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.	–  Check control for AC compressor regulating valve -N280-. –  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. –  If clogged use compressed air and nitrogen in the AC circuit. l  If no fault is found. –  Clean refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen ).

Possible deviation from specification	Possible cause of fault	Measures to be taken
l  High pressure and low pressure are normal at first, but after a while, the high pressure increases beyond the specification, l  The low pressure falls to the diagram value or lower, l  Required cooling output is not attained	t  Moisture in the refrigerant circuit.	–  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)	t  The control for the AC compressor regulating valve -N280- is defective. t  The air conditioner compressor is defective.	–  Check the activation of the air-conditioner compressor regulating valve -N280-. –  Flush the refrigerant circuit (clean) –  Renew the air conditioner compressor.

t	It is not initially necessary to clean the refrigerant circuit (flush with refrigerant R134a or blow out with compressed air and nitrogen ) when this problem occurs. Normally, there is only a small quantity of moisture in the system which can be removed by lengthy evacuation.

t

If problem involving moisture in refrigerant circuit only occurs after a lengthy operating period or only infrequently (low pressure drops below specification and evaporator ices up), it is sufficient to replace the dryer in the receiver (adjust quantity of refrigerant oil). Subsequently, evacuate refrigerant circuit for at least 3 hours.

t

A problem with evaporator output temperature sender -G263- can also cause icing-up of refrigerant circuit. In the event of such complaints it is also necessary to take into consideration the reading block for the evaporator output temperature sensor -G263- → Vehicle diagnostic tester and → heater, air conditioning; Rep. gr.87 or → air conditioning; Rep. gr..

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  the air-conditioner compressor is noisy (especially after connection), l  the requested cooling power is not achieved.	t  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 conditioner compressor. l  The quantity of refrigerant extracted is significantly greater than the prescribed charge quantity: –  Recharge refrigerant circuit. –  Repeat check.

Possible deviation from specification	Possible cause of fault	Measures to be taken
l  High pressure and low pressure are normal at first, l  the requested cooling power is not achieved.	t  Too much refrigerant oil in the circuit.	–  Drain refrigerant circuit. –  Flush the refrigerant circuit (clean)
l  High and low pressure normal l  the air-conditioner compressor is noisy (especially after connection), l  the requested cooling power is not achieved.

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 reservoir. 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.