Note | For all complaints marked with an * → Chapter. |
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| The radiator has failed completely.* |
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| Insufficient cooling capacity for all vehicle speeds or engine speeds.* |
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| No cooling or insufficient cooling after a few kilometres of driving.* |
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| The AC compressor, the air conditioner magnetic coupling -N25- or the regulating valve for compressor of air conditioning system -N280- are switched off, due to a too high or too low pressure, by the low pressure switch for air conditioning system -F73-, the high pressure switch for magnetic coupling -F118-, the air conditioner pressure switch -F129- or from the control and display unit for air conditioner -E87-, or the climatronic control unit -J255-.* |
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| No or a strong decrease of fresh air supply after a few kilometres of driving (evaporator iced up).* |
| In addition, the following complaints may still arise: |
| The air conditioning compressor makes noises |
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| Tighten the fixing screws for the AC compressor and the AC compressor bracket with a torque wrench. |
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| Check the routing of the coolant pipes, they must not be flush with other components and must be installed free of tension (align if necessary). |
| Immediately after switching on the air conditioning system and/or when cornering or braking, noises occur (refrigerant hammering): |
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| Drain refrigerant circuit, evacuate and fill again (too much refrigerant in the circuit). |
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| This complaint may also arise if there is too much refrigerant oil in the circuit (when changing the AC compressor, for example the refrigerant oil volume was not adapted). For this complaint, the refrigerant circuit must be flushed with refrigerant R134a. |
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| The refrigerant oil must be drained out of the AC compressor via the oil drain plug (replace O-ring → Electronic Catalogue of Original Parts). In order to facilitate this, the V-ribbed belt pulley or the clutch disc of the magnetic coupling must be turned by hand on the AC compressor. Then, the refrigerant circuit must be filled with refrigerant oil to its total filling capacity according to the → vehicle-specific workshop manual → Rep. gr.87 (min. 70 grams directly in the AC compressor). |
| On an air conditioning system which otherwise functions perfectly, water sprays out of the vents (the dash panel or in the footwell): |
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| Check the perfect laying of the condensation water drain, it must not be crimped or bent. |
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| Check the condensation water drain valve, it must not stick with wax or underbody sealant and must properly open and close. |
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| Check the plenum chamber cover, it must not be damaged and must be installed correctly (no water may flow into the evaporator). |
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| Check the water drainage openings of the plenum chamber, they must not be blocked (e.g. through leaves). |
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