Note: A relatively large leak can be detected, for example, by injecting purified and dried compressed air or nitrogen into the refrigerant circuit at a pressure of no more than 15 bar. If the leak is large enough, the leak location can be located by the noise emitted by the air or gas escaping from that location. Compressed air or nitrogen should be supplied through the service port.
1. The quick-release adapter for service nipples can be connected to the STOA compressor unit, for example, using a modified filling hose "A" (e.g. with a 5/8"-18 UNF thread, depending on the thread on the adapter) and a suitable adapter "B". To prevent moisture, oil and dirt from the STOA compressor unit from entering the refrigerant circulation circuit of the air conditioning system: in addition to the oil-dirt-water separator of the compressor unit, which is usually used in painting, you should use, for example, a combined fine filter, installing it between the compressor unit and the filling hose "A".
2. Through a pressure gauge block with a nitrogen reducer (rated for maximum pressure: 15 bar) "1" and filling hose "2" (for example with 5/8"-18 UNF thread) to the service nipple (to which the quick-release adapter for service fittings was connected) a gas cylinder "3" with nitrogen can be connected to the closed refrigerant circulation circuit.
3. Slowly increase the pressure in the refrigerant circuit to a maximum of 15 bar.
Attention:
- Maximum working pressure: 15 bar.
- Therefore, when searching for leaks using nitrogen, work only with a nitrogen cylinder reducer.
4. Find the leaky area by the noise emitted by the gas escaping there, or using the ultrasonic detector "VAG 1842".
5. Displace the nitrogen from the refrigerant circuit with purified and dried compressed air. Nitrogen must not enter the service cylinder. Reason: Because of this, the service cylinder is filled with non-condensable gases.
6. Eliminate leaks.
7. Perform vacuuming and recheck with a vacuum gauge for several hours. Only if the vacuum is maintained can you begin filling.
8. If there is a leak through which air does not penetrate or penetrates almost not, and the air conditioning servicing stand manages to create a sufficient vacuum: The vacuum gauge readings do not increase or increase very slowly after the stand is turned off, indicating that air penetrates and the vacuum is lost only through a very small leak.
9. Fill the circulation circuit with 100 grams of refrigerant, use an electronic leak detector to find the location of a possible leak and eliminate the leak; or fill the circuit with refrigerant with a UV contrast agent, locate the leak in the circuit using the VAS 6201 leak detection kit and repair the leak.
10. If necessary, empty the refrigerant circuit.
11. Evacuate the refrigerant circuit and repeat the vacuum gauge check within several hours. Only if the vacuum is maintained can you begin filling.