| Discharging refrigerant circuit with air conditioner service station |
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| Work procedure may vary depending on the type of tools selected; it is therefore important to observe the tool-specific operating instructions. |
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| The refrigerant circuit must be discharged if you intend to remove parts of the refrigerant circuit, if there is any doubt about the quantity of refrigerant in the circuit or if safety precautions require you to do so. |
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| All the necessary usage information for working with the refrigerant air conditioner service station can be found in the air conditioner service station operating instructions. |
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| Drain the refrigerant circuit with the air conditioner service station in line with the corresponding operating instructions. |
Caution | Risk of air conditioner compressor damage if the refrigerant circuit is empty |
| Never start the engine when the refrigerant circuit is empty |
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| Depending on the version of the air conditioner service station, the pressure in the refrigerant circuit may be less than 1 bar absolute following drainage. |
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| Depending on the version, the air conditioner compressor may be damaged by running it when the pressure in the refrigerant circuit is low |
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| Never start the engine if the pressure in the refrigerant circuit is below ambient pressure |
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| There is a possibility of refrigerant oil being extracted from the refrigerant circuit together with the refrigerant. To ensure air conditioner compressor lubrication, the refrigerant oil in the circuit must be topped up with fresh oil → Chapter. |
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| On vehicles fitted with an air conditioner compressor with no magnetic clutch (with an air conditioner compressor regulating valve -N280-), the engine should not be run for longer than absolutely necessary with the refrigerant circuit empty and high engine speeds are to be avoided (constant air conditioner compressor operation). |
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| On vehicles with an air conditioner compressor with no magnetic clutch, the engine is only to be started following complete assembly of the refrigerant circuit (avoid high engine speeds). |
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| Depending on the version of the air conditioner compressor, the high-pressure end of the air conditioner compressor may be fitted with a valve to prevent the backflow of liquid refrigerant into the compressor after switching off the air conditioning system. If an air conditioner compressor with this valve is fitted on a vehicle with a refrigerant circuit with an expansion valve, a relatively long period may elapse before the pressure on the high-pressure end decreases (the expansion valve is cold and the pressure on the low-pressure end increases rapidly after switch-off, the expansion valve closes and the refrigerant can only flow slowly to the low-pressure end). If the air conditioner compressor is switched on (or the refrigerant circuit is discharged via the low-pressure end), the pressure on the low-pressure end decreases, the expansion valve opens and the refrigerant can flow to the low-pressure end. |
| If, after drainage, work not requiring the air conditioner service station is to be performed on the vehicle, |
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| disconnect the air conditioner service station from the refrigerant circuit and switch it off. |
| If, after drainage, the refrigerant circuit is to be evacuated and re-charged, refer to → Chapter. |
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