Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Cooling Performance - With Manually Regulated A/C System, Checking: Notes
Special tools and workshop equipment required
- Diagnostic operation system VAS 5051 A (or Vehicle Diagnosis and Service System VAS 5052).
- Hose Clamps, Up to 40 mm. 3093
- Standard thermometer (for temperature measurements, if necessary a thermometer with 2 measuring probes for simultaneous measurement e.g. for temperature at right and left)
From MY 2010, this vehicle has a Start/Stop System for specific engines as optional equipment. If the vehicles has a manual climate control system, then, depending on the setting on the A/C Control Module -J301- (for example, the heater is on) the Stop function will prevent the engine from being started again as soon as there is a request for heating. In the cooling mode the Stop function is not limited by the A/C control module. On vehicles with an automatic climate control system, the Climatronic Control Module -J255- prevents the Stop function, depending on the setting. If, for example, defrost is selected, the Stop Function is not possible or will be interrupted and the engine will start. The same applies in the case of heating and cooling. The difference between the selected and actual temperature is greater than a specified value shown using Vehicle Diagnosis, Testing and Information System VAS 5051 under "Guided Fault Finding".
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.