A/C Unit Cooling Output, Checking

A/C Unit Cooling Output, Checking

Special tools, testers and auxiliary items required

• Vehicle Diagnostic Tester

• Commercially available thermometer with 2 measuring probes

Overview

• In this vehicle the coolant recirculation pump (V50) is controlled when the engine is running, for example, at temperature preselection "warm" on the Climatronic control module (J255) ("HI" appears in the display of the Climatronic control module and the Multi Media Interface). The coolant recirculation pump (V50) (if present, depending on the equipment and engine) is activated in this vehicle also to support the engine coolant pump. Check using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• In vehicles without a parking heater, the coolant recirculation pump and the coolant shut-off valve (N82) are not always installed (depending on the equipment and the engine).

• In vehicles with a Basic A/C system, the temperature of the air flowing out of the A/C system to the vent in the rear center console is controlled by the Climatronic control module, so that an average air temperature is set. The target temperature for the air from the vents in the rear center console is calculated via the setting for the left and right side on the Climatronic control module. However, if a setting which no longer regulates the temperature (for example, maximum heating or maximum cooling) is present on the Climatronic control module, the temperature of the air from the vent in the rear center console is no longer regulated. If, for example, maximum heating is set on the Climatronic control module for one side and maximum cooling for the other side, the air for the vents in the center console is maximally heated.

• In vehicles with a Basic A/C system, the temperature of the air flowing out of the A/C system to the rear vents is controlled by the Climatronic control module, according to the setting on the rear A/C display control head (E265). The data regarding this is exchanged between the Climatronic control module and the rear A/C display control head via the data bus. Check using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• Certain A/C system functions can be switched on and off via the MMI (Multi Media Interface) under the "A/C system" function in the "car"/"car systems" menu. The A/C system control can also be influenced via presettings in the MMI (Multi Media Interface) under the "A/C system" function in the "car"/"car systems" menu. Therefore, first check the presetting in the MMI in the case of a problem with these components. Refer to Infotainment/MMI operating instructions.