Audi Workshop Service and Repair Manuals > A4 Mk2 > Heating, ventilation, air conditioning system | Auxiliary heater | Self diagnosis, V.A.G Inspection Service | Reading measured value block | Display groups as of "006” | Table of activation and deactivation conditions for "Supplementary heating” function of auxiliary heater

Table of activation and deactivation conditions for “Supplementary heating” function of auxiliary heater

Display in zone “3” of display group “006”

Code

Significance

Ambient temperature via convenience data bus system

“Supplementary heating” function cannot be activated.

–	The ambient temperature was greater than 5 °C when ignition was switched on or is now greater than 7 °C

“Supplementary heating” function can be activated.

–	The ambient temperature was less than 5 °C when ignition was switched on and is now still less than 7 °C

Activation signal from operating and display unit, Climatronic control unit -J255- of air conditioner/heater (via convenience data bus system)

“Supplementary heating” function cannot be activated.

–	No activation signal being applied (either operating and display unit, Climatronic control unit -J255- is set to “Econ” mode or no additional heat output is required to attain the set passenger compartment temperature).

“Supplementary heating” function can be activated.

–	Activation signal being applied (“Econ” mode is not set in operating and display unit, Climatronic control unit -J255- and additional heat output is required to attain the set passenger compartment temperature).

Continued in next table

Code

Significance

Continued

Engine speed (via convenience data bus)

“Supplementary heating” function cannot be activated.

–	Engine speed less than 300 rpm

“Supplementary heating” function can be activated.

–	Engine speed in excess of 300 rpm

Engine coolant temperature (via convenience data bus system)

“Supplementary heating” function cannot be activated.

–	The coolant temperature was or is greater than 78 °C (or is still greater than 71 °C now after deactivation of the auxiliary heater as supplementary heater)

“Supplementary heating” function can be activated.

–	The coolant temperature is less than 78 °C (or is now less than 71 °C again after deactivation of the auxiliary heater as supplementary heater)

Coolant temperature in auxiliary heater

“Supplementary heating” function cannot be activated.

–	The coolant temperature was or is greater than 78 °C (or is still greater than 71 °C now after deactivation of the auxiliary heater as supplementary heater)

“Supplementary heating” function can be activated.

–	The coolant temperature is less than 78 °C (or is now less than 71 °C again after deactivation of the auxiliary heater as supplementary heater)

Ignition (via convenience data bus system)

“Supplementary heating” function cannot be activated.

–	Ignition switched off (no voltage at terminal “15”)

“Supplementary heating” function can be activated.

–	Ignition switched on (voltage at terminal “15”)

Note

t	On vehicles with petrol engine, the auxiliary heater is only switched on as supplementary heater with the display “111111” if this function has been activated in adaption channel “06” of the auxiliary heater control unit -J364- → Chapter.

t	The request for additional heat output is calculated and transmitted by the operating and display unit, Climatronic control unit -J255- of the air conditioner/heater. → Air conditioning; Rep. Gr. 01 and → Heating; Rep. Gr. 01