| A = This proportion of the coolant in % is conveyed in the large coolant circuit |
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| If the heater coolant shut-off valve -N279- is not actuated, all the coolant flows in the large circuit. |
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| The heater coolant shut-off valve -N279- is actuated by the auxiliary heater control unit -J364- in line with the coolant temperature and the request set. |
| B = Temperature of coolant in auxiliary heater in °C |
| C = ON signal for auxiliary heater (also as supplementary heater) via convenience data bus system |
| D = The auxiliary heater is in the control interval, however the coolant temperature continues to increase, e.g. with engine running. |
| E = The auxiliary heater is in the control interval, the coolant temperature decreases (also with engine running if more heat is emitted by the heat exchanger of the air conditioner/heater than is generated by the engine). |
| F = Auxiliary heater re-start from control interval |
Note | t
| Depending on ambient temperature and the quantity of heat emitted by the heat exchanger of the air conditioner/heater, the actuation of the heater coolant shut-off valve -N279- may remain in the various operating statuses for a lengthy period. |
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| Actuation of the heater coolant shut-off valve -N279- is also maintained if the engine is started with the auxiliary heater in operation. |
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| At a coolant temperature of approx. 91 °C, the auxiliary heater switches from control mode to control interval. During the control interval, the heater coolant shut-off valve -N279- is not actuated and the coolant flows in the large coolant circuit. |
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| The heater coolant shut-off valve -N279- is only fitted/actuated at present on vehicles with 6-cyl. engine. If vehicles with 4-cyl. engine are fitted with a heater coolant shut-off valve -N279-, the valve is currently not actuated → Chapter (encoding auxiliary heater). |
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| On vehicles with 4-cyl. engine, the heater coolant shut-off valve -N279- is not actuated at present. Vehicles manufactured up to Model Year 2004 may be fitted with a shut-off valve, but this is not actuated (the auxiliary heater control unit -J364- must be encoded accordingly). |
| t
| At the start of production (up to Model Year 2004), vehicles with 4-cyl. engine were fitted with the heater coolant shut-off valve -N279-. However, in view of the fact that cold starting problems may be encountered with these engines at very low ambient temperatures following auxiliary heating operation with a small coolant circuit (engine is only slightly pre-heated), the auxiliary heater control unit -J364- is to be encoded such that the heater coolant shut-off valve -N279- is not actuated. |
| t
| On vehicles with no heater coolant shut-off valve -N279-, the coolant always flows in the large coolant circuit. |
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