| Checking cooling output of air conditioner (vehicles with a high-voltage system only) |
| Not for vehicles with a mechanically driven air conditioner compressor |
| Procedure for vehicles with a high-voltage system only (hybrid vehicles with electrically driven air conditioner compressor) |
| As work in the vicinity of high-voltage system components is necessary for the following sequence of operations, perform „Visual inspection of high-voltage components and cables for damage“ → Chapter and heed the „General warnings for working on high-voltage system“ → Electrical system; Rep. gr.93 |
WARNING | Danger from unexpected engine starting |
| When performing general work on vehicles with a high-voltage system, switch off the ignition and remove the ignition key from the passenger compartment. |
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WARNING | Working on vehicles with high-voltage wiring: |
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| Do not support yourself or tools on high-voltage wiring or associated components --> this can damage the insulation. |
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| High-voltage wiring must not be excessively bent or kinked --> this can damage the insulation. |
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| The round high-voltage connectors are colour-coded with an external coloured ring and are provided with mechanical coding or guide lugs. It is important to observe this coding when joining up the round high-voltage connectors, otherwise the connectors can be damaged. |
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DANGER! | Risk of fatal injury if high-voltage components are damaged. |
| Observe the following when working in the vicinity of high-voltage components or wiring: |
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| It is not permitted to use cutting or forming tools, other sharp-edged tools or heat sources such as welding, brazing, soldering, hot air or thermal bonding equipment. |
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| Before starting work, visually inspect the high-voltage components in the areas involved. |
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| Before working in the engine compartment, visually inspect the power electronics -JX1-, electric drive motor -V141-, air conditioner compressor -V470- and high-voltage wiring. |
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| Before working on the vehicle underbody, visually inspect the high-voltage wiring and covers. |
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| Before working on the rear section of the vehicle, visually inspect the high-voltage wiring and the electro-box with the maintenance connector for high-voltage system - TW -. |
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| Visually inspect all potential equalisation lines. |
| Check the following when making the visual inspection: |
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| There must be no external damage on any component. |
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| The insulation of the high-voltage wiring and potential equalisation lines must not be damaged. |
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| There must be no unusual deformation of the high-voltage wiring. |
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| All high-voltage components must be identified by a red warning sticker. |
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| Working with ignition switched on or high-voltage system active |
DANGER! | Danger from unexpected engine starting and risk of poisoning in enclosed areas when working with the ignition switched on or with READY activated. Risk of parts of the body and/or clothing becoming trapped or caught up. |
| Take the following action before switching on the ignition: |
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| Move the selector lever to position P |
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| Activate the parking brake |
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| Switch off the ignition |
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| Connect a charger, e.g. Battery charger -VAS 5095A- to the jump start points of the 12 V vehicle electrical system |
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| For checking and measurement work where READY has to be active or the ignition switched on, set the selector lever to position „P“, activate the parking brake, arrange the necessary tools such that they cannot come into contact with rotating engine components and be sure to keep well away from rotating components when the engine is running. |
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| The selector lever is also to be set to position „P“ and the parking brake activated for checking and measurement work where the ignition has to be switched on but READY does not have to be active. |
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| READY is displayed in the control unit in dash panel insert -J285- via the „Powermeter“ → Owner's manual. |
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| For READY activation and deactivation, refer to → Owner's manual (heed the display in the control unit in dash panel insert -J285- when doing so). |
| Special tools and workshop equipment required |
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| Vehicle diagnostic, testing and information system -VAS 5051/- or vehicle diagnostic and service information system -VAS 5052- with the corresponding connecting cable. |
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| Battery charger, 60 A -VAS 5904- |
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| Commercially available thermometer (for temperature measurement; if applicable use thermometer with 2 probes for simultaneous measurement of temperature e.g. on right and left) |
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| READY is displayed in the control unit in dash panel insert -J285- via the „Powermeter“. |
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| Activate READY (and heed the display in the control unit in dash panel insert -J285-) → Owner's manual. |
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| The selector lever is to be set to position „P“ and the parking brake activated for checking and measurement work where the ignition has to be switched on but READY does not have to be active. |
| Problems relating to poor or insufficient cooling output at the battery cooling module on vehicles with a high-voltage system when the cooling output at the evaporator in the air conditioning unit is OK may be caused by the following: |
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| This vehicle is fitted with 2 evaporators (one in the air conditioning unit and one in the battery cooling module). If the measured temperature corresponds to or is below the specified value at one evaporator but the required specified value is not attained at the other evaporator, the system is controlled as follows: The battery regulation control unit -J840- actuates the electric air conditioner compressor at a higher speed via the power and control electronics for electric drive -JX1- and the control unit for air conditioning compressor -J842-. This causes the cooling output of the air conditioner to increase and the pressure on the low-pressure side and the evaporator temperature to drop. If the temperature set value is then not reached at one evaporator, -J840- actuates the refrigerant shut-off valve 1 for hybrid battery -N516- or the refrigerant shut-off valve 2 for hybrid battery -N517- such that refrigerant no longer flows through the evaporator which is too cold → Vehicle diagnostic tester, „Guided fault-finding“ function for air conditioner |
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| As the output of the evaporator in the battery cooling module is considerably less than that of the evaporator in the air conditioning unit, the specified temperature required may still be attained in the battery cooling module with insufficient refrigerant in the circuit, however the specified temperature will no longer be attained in the evaporator in the air conditioning unit (although the air conditioner compressor is being actuated at a higher speed). |
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| Prerequisites for checking cooling output of air conditioner → Chapter |
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