Heater coolant shut-off valve N279 actuation — AUDI

Heater coolant shut-off valve
N279
actuation
A = This proportion of the coolant in % is conveyed in the large coolant circuit
If the
heater coolant shut-off valve
N279
is not actuated, all the coolant flows in the large circuit.
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
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.
Actuation of the
heater coolant shut-off valve
N279
is also maintained if the engine is started with the auxiliary heater in operation.
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.
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).
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).
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.
On vehicles with no
heater coolant shut-off valve
N279
, the coolant always flows in the large coolant circuit.