Cooling System: Description and Operation

If the coolant temperature after switching off the engine is > 110° C, the coolant temperature is then monitored for a period of up to 1.5 minutes. If the coolant temperature rises above 110° C during this period as a result of being heated up by the engine, the heating water circulation pump (A31m1) starts the coolant circuit flowing in order to avoid local hot spots and the formation of vapor bubbles. The maximum period of this engine off cooling is 10 minutes. The engine off cooling program is ended prematurely if the coolant temperature drops to < 116° C.
Position of the components when engine off cooling operating:
- Power supply relay (K30) "On"
- Heating water circulation pump (A31m1) "On"
- Heater blower (A32m1) "Off"
- Pulsed valves (A31y1/2) closed, bypass circuit for engine off cooling open.