SEAT Workshop Service and Repair Manuals > Leon Mk2 > Heating, ventilation, air conditioning system | Heating and air conditioning | Heating | Heating controls: operation, removing and fitting | Functions of the Heating control unitJ65 | Activation of the engine control unit (in direct injection petrol engines ?FSI? and/or an engine with refrigeration controlled b

Activation of the additional heating ( in vehicles without air conditioning) > < Activation of the seat heating (optional equipment)

Activation of the engine control unit (in direct injection petrol engines „FSI“ and/or an engine with refrigeration controlled by this family of characteristics

Special tools and workshop equipment required

t	105-pin tester box -V.A.G 1598/42-1-

t	Vehicle diagnostic, testing and information system -VAS 5051 A- with the multimeter cables -VAS 5051/7-

Note

These functions depend on the version of the engine and engine control unit and are not available for all vehicles → Current flow diagrams, Electrical fault finding and Fitting locations and → Guided Fault Finding function of vehicle diagnostic, testing and information system VAS 5051 (for the relevant engine control unit).

On vehicles with manually controlled air conditioner, the air conditioning system control unit -J301- exchanges information with the corresponding engine control unit by way of the data bus system (reading measured value block of manual air conditioner) and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051". (for the manual air conditioner and the corresponding engine control unit).

t	There is a potentiometer fitted on the Heating control unit -J65-. This potentiometer is activated by the dial controller for temperature selection -A- and through this the engine control unit is informed of the position of the temperature dial position.

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Where vehicles have refrigeration controlled by a characteristic field, the engine control unit in certain engines influences the activation of therefrigeration thermostat of the engine regulated by a map of characteristics -F265-. When the temperature selector switch -A- is at the limit for „Warm“ or is positioned just before this, the temperature of the refrigerant is reduced (limited to approx. 95 °C), to prevent the air outlet temperature to the vents of the heater from being too high → Vehicle diagnostic, testing and information system VAS 5051 in the function "Guided fault finding". (for the relevant engine control unit).

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In vehicles with certain direct injection petrol engines „FSI“, the relevant engine control unit influences the fuel mixture preparation. When the temperature selector switch -A- is at the limit for „Warm“ or is positioned just before this, the mode stratified loading for the preparation of the mixture is initiated to achieve an improved heating of the refrigerant (and therefore, an increased heating performance). The engine runs in normal mode → Vehicle diagnostic, testing and information system VAS 5051 in the function "Guided fault finding". (for the relevant engine control unit).

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For vehicles that have been fitted with this function, a voltage of approx. 5 V (of the respective engine control unit) is applied to the electric connector -B- (between contacts „1“ and „10“) when the ignition is turned on. → Current flow diagrams, Electrical fault finding and Fitting locations and → Vehicle diagnostic, testing and information system VAS 5051 in the function "Guided fault finding". (for the relevant engine control unit).

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A voltage of approx. 0.5 V (at the limit „cold“) and approx. 4.5 V (at the limit „warm“) is released via the contact „2“ on the electric connector -B- to the Heating control unit -J65--A-, depending on the position of the rotary switch for selecting the temperature -A-. The relevant engine control unit detects the position of the temperature controller -A- through this voltage. The engine control unit evaluates this voltage and regulates coolant temperature and mixture formation in line with the stored characteristic curves. → Vehicle diagnostic, testing and information system VAS 5051 in "Guided fault finding" function. (for the relevant engine control unit).

Heating, ventilation, air conditioning system
Heating and air conditioning / Heating
Heating controls: operation, removing and fitting / nctions_of_the_heating_control_unitj65/">Functions of the Heating control unitJ65
Activation of the engine control unit (in direct injection petrol engines ?FSI? and/or an engine with refrigeration controlled b

Activation of the additional heating ( in vehicles without air conditioning) > < Activation of the seat heating (optional equipment)