Note | t
| The temperature of the components of the refrigerant circuit should be the same as the ambient temperature. |
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| If individual components of the refrigerant circuit are warmer or colder, then the pressure will deviate from the values shown in the tables. |
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| Absolute pressure means that 0 bar corresponds to an absolute vacuum. The normal ambient pressure (positive pressure) corresponds to 1 bar absolute pressure. On most pressure gauges, a reading of 0 bar corresponds to an absolute pressure of one bar (which is confirmed by the existence of a -1 bar marking beneath the 0 scale marking). |
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| Where vehicles have a high-pressure sender -G65- which indicates the measured pressure in the measured values block, the measured pressure should agree with the values in the tables. |
| The pressure in the refrigerant circuit is lower than indicated in the table. |
| Insufficient refrigerant in circuit. |
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| Check for leaks in the refrigerant circuit → Chapter. |
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| Check the high-pressure safety valve. |
| If the high-pressure safety valve has blown off: |
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| Check activation of radiator fan. |
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| Check refrigerant pipes and refrigerant hoses for restrictions in cross-section at bends that have too tight radius. |
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| Check refrigerant pipes and refrigerant hoses for external damage. |
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| If no defects are found, blow through refrigerant circuit with compressed air and nitrogen. |
| The pressure in the refrigerant circuit is equal to or greater than that in the table. |
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| Set air conditioning system for maximum cooling output. |
Note | If the low-pressure switch had been removed in order to connect the air conditioner service station, bridge the electrical connections in the respective connector for pressure measurement. |
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| The air conditioner compressor is driven by the engine via the air conditioning system magnetic clutch -N25-. |
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| The air conditioner compressor regulating valve -N280- is activated by the Climatronic control unit -J255-. |
| If the air conditioner compressor is not driven or the regulating valve not activated when the engine is running: |
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| Determine the cause, e.g. by reading the event memory for the air conditioning system, and rectify it. |
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| Observe the test prerequisites. |
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| Check power supply for air conditioning system magnetic clutch -N25-. If this is OK, repair magnetic clutch. |
| –
| Check actuation of air conditioner compressor regulating valve -N280-. |
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