The auxiliary coolant pump is mounted on the heater housing and is used as an aid to facilitate the flow of coolant through the FFBH and the heater core.
When FFBH is active, the auxiliary coolant pump is constantly running. When the FFBH is not in operation, the coolant is circulated by the engine coolant pump. The auxiliary coolant pump is controlled by direct power supply from the control module in the FFBH.
Vehicles equipped with the system «Stop/Start»
During the cycle «Stop/Start», when the engine is off and therefore the coolant pump is not operating, it is not possible to maintain the set temperature in the passenger compartment for a long time, especially at low ambient temperatures. To avoid this situation, an additional electric cooling system pump is installed, which is controlled by the ECM (engine control module) and is integrated into the cooling system to circulate coolant through the interior heater radiator. This circulation maintains the set temperature in the passenger compartment and, accordingly, prevents premature restart of the engine.
On vehicles with oil-fired auxiliary heater (FFBH), the auxiliary coolant pump is not installed. Instead, an auxiliary cooling system pump is used to circulate coolant when the engine is turned off. The pump is switched on by CJB (central electrical box) with oil-fired auxiliary heater (FFBH). For more information, see the chapter: Starting system (303-06C Starting system - 2.2L Duratorq - Td4, Vehicles built from 03/2009, Description and function).
Comments on this article