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 additional heating ( in vehicles without air conditioning)

Heating control unit: removing and fitting > < 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)

Only Vehicles with diesel engine

Note

Vehicles with Diesel engines currently have electric powered additional air heating. This system applies heating to the air when this leaves the heating radiator if so requested by the heating control panel (heating control unit -J65-). The activation of the electric additional heating is performed by the additional air heating control unit -J604- or the engine control unit (in 3 phase version through the low temperature relay -J359- and the high temperature relay -J360-) → Vehicle diagnostic, testing and information system VAS 5051 in the function "Guided fault finding" (fault finding assisted by the relevant engine control unit) and → Current flow diagrams, Electrical fault finding and Fitting locations

There are different versions of additional air heaters: In vehicles with a diesel engine that have been built from 2006 (smooth conversion), the heater element for additional air heater -Z35- is activated via the additional air heating control unit -J604-. Vehicles with diesel engine manufactured as of November 2006 (gradual conversion) are fitted with a 3-stage supplementary heater element -Z35- which is actuated by the corresponding engine control unit via a relay → Current flow diagrams, Electrical fault finding and Fitting locations and → "Guided fault-finding" function of vehicle diagnostic, testing and information system VAS 5051 (Fault finding assisted for the relevant engine control unit).

t	The inspection of the control for the electric supplementary heater in vehicles with additional air heating control unit -J604- is described in the guided fault finding of the air conditioner. → Measurement, information and diagnosis of vehicles system VAS 5051 in "Guided fault finding" function.

t	The measured values block of the additional air heating control unit -J604- indicates whether the additional heating activates or, if not, why it does not when a request is made and → Vehicle diagnostic, testing and information system VAS 5051 in the function "Guided fault finding".

The inspection of the control for the electric supplementary heater in vehicles with 3 stage heater element for additional air heater -Z35- is described in the guided fault finding of the respective engine control unit. → Measurement, information and diagnosis of vehicles system VAS 5051 in "Guided fault finding" function.

t	For vehicles with a petrol engine, no additional heating is fitted.

Check the activation of the heating control panel (heating control unit -J65-)

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-

t	There is a switch fitted on the Heating control unit -J65-. This switch can be moved (closed) to the limit „warm“ using the rotary switch for selecting the temperature -A- in the scope of the adjustment of approx. 3 hours.

–

If the heating switch is closed, the electronics of the Heating control unit -J65-, with the ignition on, connects through pin „7“ earth to the Additional air heating control unit -J604-. The Additional air heating control unit -J604- detects that more heating power is required and activates the additional electric heating, if the remaining conditions for activation are fulfilled in the Additional air heating control unit -J604-.

t	Connection conditions for electric additional heating (activation of the heating element for additional heating -Z35-) of the additional air heating control unit -J604-

t	Connection conditions for independent heating as additional heating (in the additional heating control unit -J364-) in vehicles with the extra equipment → independent heating; Rep. gr.

Connection conditions for electric additional heating (activation of the heating element for additional heating -Z35-) of the relevant engine control unit → Vehicle diagnostic, testing and information system VAS 5051 in the function "Guided fault finding". (Fault finding assisted for the relevant engine control unit).

Note

In order for the relevant engine control unit to activate the heating element for additional heating -Z35- with three phases via the low temperature relay -J359- and the high temperature relay -J360-, the same conditions must be met in the engine control unit as in the air conditioning control unit -J301- in vehicles with manual climate control.

Connection criteria for activation of electric additional heating

–	The engine control unit activates the low temperature relay -J359-, the high temperature relay -J360- and the heating element for additional heating -Z35- if the following prior conditions are met:

t	The engine control unit receives an earth signal from the heating control unit -J65-.

t	The engine has been running for at least 8 seconds and the engine speed is over 500 rpm.

t	The engine temperature is below 75 °C

t	Calculated ambient temperature is lower than 8° C

t	The onboard voltage is over 12.2 V and the onboard network control unit -J519- does not send any signal to block the connection.

t	No fault is stored in the engine control unit and the alternator -C- stress is below 30 ...77% (depending on the engine speed)

Note

In vehicles with 3 stage heater element for additional air heater -Z35-, the engine control unit activates both relays for the additional heating in such as way that the loading of the generator -C- does not exceed 95 %. → Measurement, information and diagnosis of vehicles system VAS 5051 in "Guided fault finding" function.(for the relevant engine control unit) and → Current flow diagrams, Electrical fault finding and Fitting locations. The following phase only connects when the alternator -C- stress is below 30 ...77% (depending on engine speed)

Disconnection criteria for additional heating

Note

Vehicles without air conditioning cancel the activation if the engine control unit fails to meet the connection criteria, or detects one of the disconnection criteria.

t	If one of the connection conditions is lost

t	Calculated ambient temperature greater than 11° C

t	The alternator -C-stress is over 95%.

t	The engine control unit does not receive an earth signal from the heating control unit -J65-.

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 additional heating ( in vehicles without air conditioning)

Heating control unit: removing and fitting > < Activation of the engine control unit (in direct injection petrol engines ?FSI? and/or an engine with refrigeration controlled b

SEAT Workshop Service and Repair Manuals

Leon Mk2

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 additional heating ( in vehicles without air conditioning)

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 additional heating ( in vehicles without air conditioning)

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 additional heating ( in vehicles without air conditioning)

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 additional heating ( in vehicles without air conditioning)