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Display group "003” > < Display group "001”

A4 Mk2

Display group “002”
Display group “002”
Current coolant temperature in auxiliary heater, actuation of heater coolant shut-off valve -N279-, lowest measured or transmitted temperature and specified speed for combustion air blower -V6-
   
Display zoneDisplay
1Current coolant temperature in auxiliary heater (in °C)
–  The coolant temperature displayed is measured by the temperature sensor -G18-.
l  Check measured value → Chapter

  Note
t  The temperature sensor -G18- is installed in the auxiliary heater. The temperature measured by the sensor will be too low if dirt has accumulated at the temperature sensor -G18-.
t  If the fault “Heater overheating” is displayed, check the temperature sensor -G18-.
   
Display zoneDisplay
2Heater coolant shut-off valve -N279- actuation
l  Display = 100 %
–  The heater coolant shut-off valve -N279- is not actuated (large coolant circuit, coolant is drawn in by the auxiliary heater via the engine).
l  Display = 1 to 100 %
–  The heater coolant shut-off valve -N279- is actuated in control mode (depending on actuation, the coolant is drawn in by the auxiliary heater directly from the heat exchanger or via the engine).
l  Display = 0 %
–  The heater coolant shut-off valve -N279- is constantly actuated (small coolant circuit, coolant is drawn in by the auxiliary heater directly from the heat exchanger).
t  Check heater coolant shut-off valve -N279- → Chapter

  Note
t  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.
t  In auxiliary heating mode with no “engine pre-heating” function, the heater coolant shut-off valve -N279- is actuated up to a coolant temperature of 71 °C such that the majority of the coolant flows directly back to the auxiliary heater from the heat exchanger (small coolant circuit). As soon as the coolant temperature exceeds 71 °C, the auxiliary heater control unit -J364- actuates the heater coolant shut-off valve -N279- such that a coolant temperature of greater than approx. 71 °C is set in the auxiliary heater. If the coolant temperature exceeds 90 °C, the heater coolant shut-off valve -N279- is no longer actuated (large coolant circuit).
t  If the control unit in dash panel insert -J285- is set to the “engine pre-heating” function, some of the coolant always flows via the engine coolant circuit, thus pre-heating the engine as well. The passenger compartment takes somewhat longer to warm up.
t  If the engine is started with the auxiliary heater switched on, the heater coolant shut-off valve -N279- is again actuated by way of the coolant temperature measured in the auxiliary heater with allowance for engine temperature. This also applies to the “supplementary heating” function on vehicles with diesel engine.
   
Display zoneDisplay
3Lowest temperature (in °C) determined or measured since auxiliary heater activation
–  Allowance is only made for the coolant temperature transmitted by the control unit in dash panel insert -J285- if a valid value is supplied (⇒ display zone “3” in display group “009”)

  Note
t  The auxiliary heater control unit -J364- evaluates the temperatures received via the convenience data bus system and the temperature measured by the temperature sensor -G18- and bases its calculations on the lowest value on start-up of the auxiliary heater.
t  Depending on the coolant temperature sensor version, the control unit in dash panel insert -J285- cannot evaluate the measured value of the coolant temperature sensor at low temperatures or a voltage is required at terminal “15” (ignition on) for evaluation purposes.
t  The temperature displayed in this zone is used by the auxiliary heater control unit -J364- for example to calculate the battery temperature.
   
Display zoneDisplay
4Specified speed (actuation) of combustion air blower -V6- (in rpm)
l  Display = 0 rpm
–  Combustion air blower -V6- is not actuated
l  Display = 4500.....8500 rpm
–  Combustion air blower -V6- is actuated in control mode
t  Check combustion air blower -V6- → Chapter

  Note
t  In full load operation, the auxiliary heater control unit -J364- actuates the combustion air blower -V6- such that it runs at a speed of approx. 7800 to 8100 rpm. In part load operation (control mode), the combustion air blower speed is regulated to between 4800 and 6000 rpm.
t  The combustion air blower speed (and metering pump actuation) and thus the heat output are reduced by the auxiliary heater control unit -J364- if the voltage decreases at the auxiliary heater control unit -J364-.
t  If the power factor display in zone “1” of display group “003” is 100%, the combustion air blower speed must be roughly 7800 to 8100 rpm.
   

Display group "003” > < Display group "001”