Refrigerant Circuit, Locating Leaks with Leak Detection System VAS 6201

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NOTE:

Certain leaks are difficult or even impossible to locate using an electr. leak detector. In such cases, use can be made of the leak detection system VAS 6201.
Refrigerant circuit leaks result in a loss of refrigerant oil together with the refrigerant. This oil generally remains in the vicinity of the leak location. Adding a small quantity of fluorescent fluid to the refrigerant circuit makes this oil visible under UV light. The fluid (PAG oil containing an additive which shows up under UV light) is poured into the refrigerant circuit and becomes distributed with the refrigerant oil when the air conditioner is switched on.
The air conditioner must be operated for at least 60 min. to distribute the additive throughout the refrigerant circuit (compressor must run).
The refrigerant oil containing the additive (which shows up under UV light) can either be poured directly into the open circuit or pumped in with the circuit charged using the hand pump VAS 6201/1 (from leak detection system VAS 6201) via the service connection on the low-pressure side.
If the leak detection additive is applied via the service connection on the low-pressure side with the refrigerant circuit charged, a small quantity of additive remains in the service connection. This is to be carefully removed so as to avoid subsequent erroneous leak detection.
If a component forming part of a circuit into which the leak detection additive is poured has to be replaced, thoroughly clean joints with other components after assembling refrigerant circuit. Otherwise, the remnants could lead to erroneous leak detection.
On discharging the refrigerant circuit, refrigerant oil and thus also leak detection additive enters into the A/C service station. The oil is removed from the refrigerant in the oil separator of the A/C service station and discharged from the A/C service station via the drain. The refrigerant oil drained off is not to be poured back in. It is to be replaced with fresh refrigerant oil.
Pay attention to the following if leak detection fluid has already been poured into a refrigerant circuit in the course of previous repair work: Only add new leak detection fluid if refrigerant oil is replaced. If only some of the refrigerant oil has been replaced, just add the corresponding quantity of leak detection fluid. If, for example, 100 ml of refrigerant oil has been replaced on a vehicle containing 250 ml, only add 1 ml (cm ³ ) of leak detection additive.
Certain materials and their compounds (e.g. oxidation products on aluminum components, anti-corrosion waxes) also show up under UV light.

Fig 1: Identifying Tools & Items Required -- Refrigerant Circuit, Locating Leaks With Leak Detection System VAS 6201

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Tools and other items required:

Hand pump with low-pressure service hose, service coupling and non-return valve VAS 6201/1
Cartridge VAS 6201/2
Cleaning agent VAS 6201/3
UV leak detection lamp VAS 6201/4
UV-absorbing safety goggles VAS 6201/6
Sticker VAS 6201/7
Tube VAS 6201/8 VAS 6201/8
Protective gloves VAS 6201/9

Pouring in leak detection additive with refrigerant circuit empty

Fig 2: Identifying Cartridge & One Unit

Courtesy of VOLKSWAGEN UNITED STATES, INC.

The cartridge - A - contains 15.4 ml of leak detection additive (one unit - B - corresponds to 2.5 ml).

Fig 3: Assembling Hand Pump VAS 6201 With Cartridge - VAS 6201/2

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Assemble hand pump VAS 6201 , item - 1 - with cartridge, item - 2 - VAS 6201/2.

Insert tube VAS /8 ( → VAS 6201/8 item - 7 - ) in hand pump.

Open hand pump service valve.

Fig 4: Identifying Leak Detection Additive Poured In Via An Open Connection

Courtesy of VOLKSWAGEN UNITED STATES, INC.

With refrigerant circuit empty, the leak detection additive can best be poured in via an open connection.

Open the refrigerant circuit at a readily accessible connection.

Cover the surrounding area with sheeting or absorbent paper.

Hold tube upwards.

Screw in toggle of hand pump until leak detection additive emerges from tube.

Fill the refrigerant circuit with 2.5 ⁺ / _- 0.5 ml (milliliter = cm ³ ) of leak detection additive.

Replace O-ring at open connection.

Assemble refrigerant circuit.

Affix sticker next to service connections to indicate that leak detection fluid has been added to the refrigerant circuit.

Evacuate and charge refrigerant circuit as specified.

NOTE:

Pay attention to the following if leak detection fluid has already been poured into a refrigerant circuit in the course of previous repair work: Only add new leak detection fluid if refrigerant oil is replaced. If only some of the refrigerant oil has been replaced, just add the corresponding quantity of leak detection fluid. If, for example, 100 ml of refrigerant oil has been replaced on a vehicle containing 250 ml, only add 1 ml (cm ³ ) of leak detection additive.
The air conditioner must be operated for at least 60 min. to distribute the additive throughout the refrigerant circuit (compressor must run).
Depending on the magnitude and location, it may take several days for sufficient refrigerant oil and additive to emerge to clearly identify the leak.