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Special tools, testers and other items required > < Layout of components for auxiliary heater in vehicle

A4 Cabriolet Mk2

Removing and installing heater coolant shut-off valveN279
Removing and installing heater coolant shut-off valve -N279-
  Note
t  Currently only actuated on vehicles with 6-cyl. engine.
t  Vehicles with 4-cyl. engine are not provided with a heater coolant shut-off valve -N279- at present. Vehicles manufactured up to Model Year 2005 may be fitted with a shut-off valve, but this is not actuated (the auxiliary heater control unit -J364- must be encoded accordingly) → Chapter (Encoding auxiliary heater).
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  If voltage is not applied to the heater coolant shut-off valve -N279- (large coolant circuit), the coolant can flow from the connection for hose -D- (from the air conditioner unit/heater heat exchanger) to the connection for hose -B- (to the engine).
t  If voltage is applied to the heater coolant shut-off valve -N279- (small coolant circuit), the coolant can flow from the connection for hose -D- (from the air conditioner unit/heater heat exchanger) to the connection for hose -C- (to the auxiliary heater).
t  Connection -G- is sealed with a plug.
t  In auxiliary heating mode, the heater coolant shut-off valve -N279- is actuated by the auxiliary heater control unit -J364- until the coolant temperature in the auxiliary heater has reached a specified level → Chapter.
  A82-0352

Special tools, testers and other items required > < Layout of components for auxiliary heater in vehicle