Searching For Refrigerant Circuit Leaks With Compressed Air Or Nitrogen
This Service Information 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 REFRIGERANT CIRCUIT, EVACUATING WITH A/C Service Station .
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 a vehicle if its service history is unknown.
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.
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 REFRIGERANT CIRCUIT, CLEANING 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.
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 IMPROVISED TOOLS . To prevent moisture, oil or contaminants from the air compressor from entering the A/C system 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 Special Tools and Equipment Information.
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 (59 °F)) -1- and a filler hose -2- (for example, with 5/8" 18 UNF threads) connected to the service connection (a quick-release coupling adapter has to be connected to the service connections). IMPROVISED TOOLS
-- Slowly increase the pressure in the refrigerant circuit to a maximum of 15 bar (218 psi).
- Use a pressure reducer for the nitrogen container.
-- 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 off the A/C 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 Kit:VAS6201 or succeeding model and repair it. Refer to REFRIGERANT CIRCUIT, TRACING LEAKS, WITH Electronic Leak Detector or REFRIGERANT CIRCUIT, TRACING LEAKS, WITH Leak Detection System .
-- Empty the refrigerant circuit, if necessary. Refer to REFRIGERANT CIRCUIT, DISCHARGING 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.