| Blow through refrigerant circuit with compressed air and nitrogen. |
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| Compressed air must be used to remove humidity and other impurities from the refrigerant circuit. Nitrogen must be used to eliminate the humidity from the refrigerant circuit. |
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| The blowing of the refrigerant circuit using compressed air and nitrogen usually requires considerably more labour than rinsing with R134a refrigerant. When rinsing with R134a refrigerant, cleaning of components is usually more thorough and for this reason a rinse should be done for each complaint (sweeping with compressed air is carried out for specific complaints and components) |
| Blowing through the components is only applied in the following cases. |
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| If there is no possibility of rinsing the refrigerant circuit using the refrigerant R134a. |
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| When dirt and other impurities are located in the different components of the refrigerant circuit. |
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| If the vacuum display does not remain stabile when extracting refrigerant circuit (there is humidity in the refrigerant circuit which builds up pressure). |
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| If the refrigerant circuit has remained open longer than necessary for assembly (e.g. after an accident). |
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| If, based on pressure and temperature measurements in the refrigerant circuit, there may be humidity in the circuit. |
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| When this requests for the replacement of certain components of the vehicle in the specific Repair Manual → Heating, air conditioning. |
Note | t
| When blowing through the refrigerant circuit using compressed air and nitrogen, the degree of purity is not reached than when rinsing with R134a refrigerant. When rinsing using the refrigerant R134a, the refrigerant oil is released and cleaning the component is more effective. |
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| When blowing the maximum operating pressure of 15 bar must not be exceeded (when necessary, also use a pressure reducer for the compressed air). |
WARNING | t
| Nitrogen may escape from the bottle in an uncontrolled manner. |
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| Use only pressure reducers for nitrogen gas cylinders (maximum working pressure 15 bar). |
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| The mixture of gas blown out of the components must be sucked up with the appropriate extraction installations. |
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| The components must always be blown out in the opposite direction to that of the refrigerant flow. |
| Do not blow compressed air or nitrogen through the choke, expansion valve, compressor, or the liquid and collecting tanks. |
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| With condensers where a cartridge is mounted in the integrated container, the cartridge must be removed. |
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| First blow out the impurities from the container using compressed air and then the humidity using nitrogen. |
| So that no oil nor humidity from the compressed air system does not enter into the refrigerant circuit, note the following points: |
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| The compressed air must be cleaned and dehydrated by means of a compressed air cleaning device. Insert the filter and dehumidifier (part of the scope of promotion of the tools for painting work) → Workshop equipment and special tools catalogue. |
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| For refrigerant lines with thread connection or union nut, use the adapter -V.A.G 1785/1- to adapter -V.A.G 1785/8-) for connecting the filling hose 5/8" -18 UNF. These adapters are part of the Adapter set for refrigeration -VAS 6338/1- and the Adapter sets for refrigerant circuits for commercial vehicles -VAS 6338/50-. |
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| For refrigeration lines without thread or union nut, use the Adapter set for refrigeration -VAS 6338/1- or the Adapter sets for refrigerant circuits for commercial vehicles -VAS 6338/50- or a commercially available compressed air pistol with rubber nozzles. |
Note | t
| The compressed air and nitrogen flowing out of the component must be captured using a suitable device (e.g. workshop extraction unit). |
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| Certain impurities and the old refrigerant do not allow themselves to be removed at all or to be removed from certain parts of the refrigerant circuit. Such impurities can only be eliminated by rinsing then with refrigerant R134a. |
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