Auxiliary Heater Element: Description and Operation

Auxiliary Electric Heater (Z35)

• Currently an auxiliary heater is installed for vehicles with diesel engines.

• An auxiliary air heater control module (J604) and an auxiliary heater heating element are installed for vehicles with diesel engines. Via the auxiliary heater heating element the air is heated after it exits the heater core in the front A/C unit.

• Certain A/C system functions (for example, auxiliary heater activation) 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 the Infotainment/MMI operating instructions.

• The function test of the activation of the auxiliary heater heating element via the auxiliary air heater control module is described in the Guided Fault Finding of the A/C system using the Vehicle diagnostic tester in the "Guided Fault Finding" function.

• The "read measured values" function of the Guided Fault Finding of the front A/C display control head, the Climatronic control module (J255) , displays the fact that the auxiliary heater is switched on or why activation did not occur despite a request using the Vehicle diagnostic tester in the "Guided Fault Finding" function.