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Volkswagen Golf Service & Repair Manual: Leak detection in refrigerant circuit using compressed air or nitrogen

  Note
A leak in the refrigerant circuit can be detected, for example, by pressurising the circuit to a maximum of 15 bar using cleaned and dried compressed air or nitrogen → Chapter. If the leak is large, the leakage point can be detected by sound as the air or gas escapes.
   
Introduce the compressed air or the nitrogen through the service connection.
 

Leak detection in refrigerant circuit using compressed air or nitrogen

The quick-release coupling adapter for service connection can be fitted with a modified charging hose -A- (e.g. with a 5/8"-18 UNF thread, depending on the thread of the quick-release coupling adapter) and a suitable adapter -B- to connect to the workshop compressed air system → Chapter. To ensure no moisture, oil or other contaminants can enter the refrigerant circuit from the workshop compressed air system, use, for example, a supplementary combination fine filter element with an oil, dirt and water separator as normally used in paint shops. Install it between the compressed air system and the charging hose -A- → Workshop equipment catalogue.
 

Leak detection in refrigerant circuit using compressed air or nitrogen

Using the manifold gauge with pressure reducer for nitrogen (maximum reduced pressure: 15 bar) -1- you can connect a full nitrogen gas cylinder -3- via a charging hose -2- (e.g. with 5/8"-18 UNF threaded connection) to the service connection, to which a quick-release coupling adapter is connected, of a closed refrigerant circuit. → Chapter
–  Slowly increase pressure in refrigerant circuit to a maximum of 15 bar.
  WARNING
Maximum permissible working pressure: 15 bar
When searching for leaks using nitrogen, work only with a pressure reducer for nitrogen cylinders.
–  Search for leak by sound, which is created by the escaping gas. Use Ultrasonic tester -V.A.G 1842- to ease localisation of sounds.
–  Press nitrogen out of refrigerant circuit using cleaned and dried compressed air. Nitrogen must not enter the service cylinder. This prevents the service cylinder from being filled with condensable gases.
–  Rectify leak.
–  Evacuate again and observe the vacuum display over a period of hours. Charging may be done only when vacuum is maintained.
If a leak is present of a size where no or very little air is drawn in and the air conditioner service station can create sufficient vacuum. The vacuum gauge does not increase or increases very slowly after switching the air conditioner service station off, this indicates there may be a very small ingress of air and the vacuum is lost.
–  Charge circuit with 100 g of refrigerant and search for the possible leak using an electronic leak tester and rectify fault as necessary → Chapter or add an approved UV contrast substance to the refrigerant and search for the possible leak in the circuit using leak detector system VAS 6201 or later model and rectify fault as necessary → Chapter.
–  Evacuating refrigerant circuit if necessary → Chapter
–  Evacuate refrigerant circuit and observe the vacuum gauge over a period of hours. Charging may be done only when vacuum is maintained.
 

Leak detection in refrigerant circuit using compressed air or nitrogen

Detecting leaks in refrigerant circuit
  Note Different processes are described in this workshop manual for leak detection in the refrigerant circuit. These processes have been tested an ...

Searching for leaks in refrigerant circuits using leak detector -V.A.G 1796
  Note Small leaks can be detected with, for example, an electronic leak detector. –  Evacuate refrigerant circuit using an ...

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