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Home >> Volvo >> 2009 >> V70 >> Repair and Diagnosis (Single Page) >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Alarm, Electrical Control Modules, Brakes, Brake Control Module (BCM) - Design And Function >> Central Electronic Module (CEM) >> Function >> Electrical Additional Heater (Certain Markets)
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Electrical Additional Heater (Certain Markets)

Fig 1: Identifying Electrical Additional Heater
GLL154716Courtesy of VOLVO CARS CORPORATION

The climate control module (CCM) (4/6) checks the function of the electric auxiliary heater.

The central electronic module (CEM) (4/56) transmits information regularly to the climate control module (CCM), for example, about the permitted size of the current consumption.

The climate control module (CCM) uses this information to prioritize between its loads. The climate control module (CCM) also uses the information to calculate how much output must be used to activate the electrical additional heater (9/41).

The central electronic module (CEM) receives information from the climate control module (CCM) via the CAN network.

The central electronic module (CEM) checks that the output voltage is not too great. See CURRENT LIMITATION - CENTRAL ELECTRONIC MODULE (CEM) 

The power consumption of the electric auxiliary heater is regulated via a pulse-width modulated signal from the central electronic module (CEM).