| Flush refrigerant circuit with compressed air and nitrogen. |
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| To force contaminants and waste refrigerant oil out of the refrigerant circuit, compressed air is to be used. To get moisture out of the system, nitrogen is to be used. |
| The refrigerant circuit or individual components are to be blown through if: |
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| there is no way of flushing the refrigerant circuit. |
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| if there is dirt or contamination in individual components of the refrigerant circuit. |
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| if during evacuation of a leak-tight refrigerant circuit the vacuum display is not constant on gauge (moisture in the refrigerant circuit, which generates vapour pressure). |
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| if the refrigerant circuit has been left open for longer than normally required for repairs (e.g. following an accident) |
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| pressure and temperature measurements in the circuit indicate that there is moisture in the refrigerant circuit. |
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| there is doubt about the amount of refrigerant oil in the refrigerant circuit. |
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| the A/C compressor had to be changed due to internal damage (e.g. noise or no output) but only if flushing is not possible with refrigerant R134a. |
Note! | t
| Blowing through the refrigerant circuit with compressed air and nitrogen will not achieve the same degree of cleanliness as flushing with refrigerant R134a. When flushing with refrigerant R134a, the refrigerant oil is shifted and cleaning of the components is better → Chapter. |
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| When blowing through, a maximum working pressure of 15 bar must not be exceeded (if necessary, use pressure limiter for compressed air as well). |
Caution | t
| Nitrogen can escape from the bottle in an uncontrolled way. |
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| Work only with pressure limiter for nitrogen bottles (max. working pressure 15 bar). |
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| The gas mixture escaping from the components must be collected with appropriate extraction units. |
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| Always blow through components opposite the direction of refrigerant flow. |
| Compressed air and nitrogen cannot be blown through the restrictor, expansion valve, air conditioner compressor, receiver or reservoir. |
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| In cases where condensers have a drying agent cartridge in the integrated receiver, this drying agent cartridge must be removed. |
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| First blow out old refrigerant oil and dirt using compressed air and then dry components with nitrogen. |
| To prevent oil and moisture from the compressed air system making its way into the refrigerant circuit, the following points must be observed. |
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| The compressed air must be fed through a compressed air cleaning unit to clean and dry it. Therefore, use compressed air filter and dryer (included in items supplied with tools for painting work) → Workshop equipment and Special tools catalogue. |
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| If refrigerant pipes have threads or union nuts at connections, use adapter -V.A.G 1785/1- to adapter -V.A.G 1785/8- to connect to 5/8" - 18 UNF charging hoses. These adapters can be found in the adapter case for SEAT passenger vehicle set -VAS 6338/1- and adapter case for commercial vehicle set -VAS 6338/50-. |
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| On refrigerant lines without thread or union nut on the connection, use adapter from adapter case for SEAT passenger vehicle set -VAS 6338/1- or adapter case for commercial vehicle set -VAS 6338/50- or proprietary air blow gun with rubber nozzle. |
Note! | t
| Always extract any escaping air and/or nitrogen from the components using appropriate local exhaust ventilation LEV (e.g. workshop extraction system). |
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| Certain contaminants and old refrigerant oil cannot be shifted from the refrigerant circuit at all with compressed air or if the the compressed air is insufficient. These contaminants can be removed by flushing with refrigerant R134a, for example, → Chapter. |
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