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Volkswagen Touran Service Manual: Searching for Refrigerant Circuit Leaks with Compressed Air or Nitrogen

Volkswagen Touran Service Manual / Heating, Ventilation and Air Conditioning / Refrigerant Circuit, Detecting Leaks / Searching for Refrigerant Circuit Leaks with Compressed Air or Nitrogen

  Note
This repair manual describes different methods for detecting leaks in the refrigerant circuit. These methods have been tested and result in success when used correctly.
If when searching for compressed air / Nitrogen or vacuum leaks none are found, add a leak detection additive i.e UV leak detection additive, to the electric leak detecting unit.
Minor leaks can be detected using an electronic leak detector or UV leak detector lamp.
Many methods for detecting leaks in the refrigerant circuit are offered in the open market. These methods do not always have optimum results. If they are not used exactly according to specifications, they can indicate refrigerant circuit components have leaks even when they do not. Also, refrigerant circuit components can be damaged by some methods.
Do not repair components with leaks. Replace them with new original parts.
Do not charge a leaking refrigerant circuit with refrigerant. Evacuate the circuit and check it for leaks before charging. Refer to → Chapter "Refrigerant Circuit with A/C Service Station, Draining".
  Caution
If it is suspected that chemicals were added to the refrigerant circuit to seal leaks, do not connect the A/C service station and do not extract the refrigerant.
Chemicals that seal leaks in the coolant circuit form deposits that affect the function of the A/C system and lead to failure of the A/C system and the A/C service station.
Inform that customer that there are substances in the A/C system that are no approved by Volkswagen. This A/C system cannot be drained or serviced in the workshop.
  Note
VW does not approve the use of chemicals to seal leaks in the refrigerant circuit.
Chemicals used to seal leaks in the refrigerant circuit often react with air and the moisture in it. They cause deposits in the refrigerant circuit and the A/C service station and malfunctions in valves and other components that they come in contact with. These deposits cannot be removed completely from the components, even by flushing.
Chemicals used to seal leaks in the refrigerant circuit usually cannot be detected from outside. The label that should be applied to identify it is often missing. Therefore be careful when working with if you do not know its service history.
Accessories offer containers used to separate out these chemicals (used to seal leaks in the refrigerant circuit). Because VW does not approve the use of these chemicals, there is no evidence of the effectiveness of these filters.
  Note
A leak can be identified if a maximum of pressure of 15 bar (218 psi) can be generated in the refrigerant circuit using clean, dry compressed air or nitrogen. Refer to → Chapter "Refrigerant Circuit, Flushing with Compressed Air and Nitrogen". If the leak is large enough, the sound of escaping air or gas can be heard at the location of the leak.
   
Use the service connection for the compressed air or nitrogen.
  Searching for Refrigerant Circuit Leaks with Compressed Air or Nitrogen
The quick-release coupling adapter for service connections can be connected to the air compressor using a modified filler hose -A- (for example, with 5/8" 18 UNF threads, different from the threads on the quick-release coupling adapter) and a suitable adapter -B-. Refer to → Chapter "Improvised Tools". This keeps humidity, oil and dirt coming out of the workshop compressed air system from getting into the A/C refrigerant circuit. Also use a combination fine-gauge filter for compressed air systems such as those that are standard in paint shops. Install it between the compressed air system and the filler hose -A- . Refer to the Special Tools and Equipment Catalog.
  Searching for Refrigerant Circuit Leaks with Compressed Air or Nitrogen
A compressed gas cylinder filled with nitrogen -3- can be connected to the closed refrigerant circuit using a pressure gauge battery with a pressure reducer for nitrogen (maximum reduction pressure: 15 bar (218 psi)) -1- and a filler hose -2- (for example, with 5/8" 18 UNF threads) connected to the service connection. A quick-release coupling adapter must also be connected to the service connection. Refer to → Chapter "Improvised Tools".
  Slowly increase the pressure in the refrigerant circuit to a maximum of 15 bar (218 psi).
  WARNING
The maximum permitted working pressure is 15 bar (218 psi).
When testing for leaks with nitrogen, always work with a pressure reducer for nitrogen bottles.
  Find the location of the leak by listening for the sound of venting gas. An Ultrasonic Tester VAG1842S -VAG1842S- will aid in detecting the origin of noise.
  Use clean, dry compressed air to force the nitrogen out of the refrigerant circuit. The nitrogen must not get into the Service bottle. Reason: gases that do not condense do not get into the Service bottle.
  Repair the leak.
  Evacuate and again observe the vacuum display over a period of hours. Only when the vacuum is maintained can the refrigerant circuit be charged.
If there is a leak that is small enough that no air or very little air vents through it and the A/C service station can generate a sufficient vacuum. The vacuum indicator does not increase after switching the A/C system service station or only increases slowly, indicating that air is only entering through a small leak.
  Add 100 grams of refrigerant to the circuit, find the location of the leak using an electronic leak detector and repair it or add UV contrast dye to the refrigerant and find the location of the leak with the leak detection system VAS6201 or succeeding model and repair it. Refer to → Chapter "Refrigerant Circuit, Tracing Leaks, with Electronic Leak Detector -VAG1796-" or → Chapter "Refrigerant Circuit, Tracing Leaks, with Leak Detection System -VAS6196- or Leak Detection Kit -VAS6201A- or Succeeding Model".
  Empty the refrigerant circuit, if necessary. Refer to → Chapter "Discharge Refrigerant Circuit with A/C Service Station".
  Evacuate and check the vacuum display again over several hours. Only when the vacuum is maintained can the refrigerant circuit be charged.
  Searching for Refrigerant Circuit Leaks with Compressed Air or Nitrogen
Refrigerant Circuit, Detecting Leaks
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Refrigerant Circuit, Tracing Leaks, with Electronic Leak Detector -VAG1796
  Note This repair manual describes different methods for detecting leaks in the refrigerant circuit. These methods have been tested and result in ...

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