A4 Mk1
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Possible deviation from specification | Possible causes of fault | Fault elimination | ||||||||||||||||
| Not enough refrigerant in circuit or expansion valve defective |
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Note
If no fault can be found and air conditioner operation is not OK when the test is repeated, clean the refrigerant circuit (flush with refrigerant R134a → Chapter or blow out with compressed air and nitrogen → Chapter). |
Possible deviation from specification | Possible causes of fault | Fault elimination | ||||||||||||
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Possible deviation from specification | Possible causes of fault | Fault elimination | ||||||||||||||||||||||||
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Note
If operation is not OK after cleaning the refrigerant circuit (flush with refrigerant R134a → Chapter or blow out with compressed air and nitrogen → Chapter), the expansion valve must be renewed. |
Possible deviation from specification | Possible causes of fault | Fault elimination | ||||||||||||||||
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Note
t | It is not initially necessary to clean the refrigerant circuit (flush with refrigerant R134a → Chapter or blow out with compressed air and nitrogen → Chapter) 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 a problem involving moisture in the 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 renew the dryer (adjust the quantity of refrigerant oil). Subsequently, evacuate refrigerant circuit for at least 3 hours. |
Possible deviation from specification | Possible causes of fault | Fault elimination | ||||||||||||||||||||||||||||
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Note
If operation of the air conditioning system is not OK when the test is repeated, re-fit the old expansion valve and clean the refrigerant circuit (flush with refrigerant R134a → Chapter or blow out with compressed air and nitrogen → Chapter). Then renew the air conditioner compressor and receiver. |
Possible deviation from specification | Possible causes of fault | Fault elimination | ||||||||||
| The air conditioner compressor is defective. |
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Possible deviation from specification | Possible causes of fault | Fault elimination | ||||||||||||
| Expansion valve or air conditioner compressor defective. |
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Note
t | If operation of the air conditioning system is not OK when the test is repeated, re-fit the old expansion valve and clean the refrigerant circuit (flush with refrigerant R134a → Chapter or blow out with compressed air and nitrogen → Chapter). Then renew the air conditioner compressor and receiver. |
t | In this case, the evaporator may ice up although the correct quantity of refrigerant is present in the refrigerant circuit. |
Possible deviation from specification | Possible causes of fault | Fault elimination | ||||||||
| Too much refrigerant oil in the circuit. |
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Note
t | Overfilling with refrigerant oil may occur if, for example, the air conditioner compressor has been renewed without adjusting the quantity of refrigerant oil. |
t | If there is too much refrigerant oil in the circuit, drain the air conditioner compressor and renew the receiver. After cleaning the refrigerant circuit (flush with refrigerant R134a → Chapter or blow out with compressed air and nitrogen → Chapter), add the correct amount of refrigerant oil to the circuit → Chapter. |