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◆ The additional heater is available in various versions.
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◆ Note the precise assignment when replacing an additional heater:
=> Parts List
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◆ → The heater model can be seen from the rating plate.
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‒ Type "Z/C-D" without or with recirculating pump -V55 = additional heater (only for vehicles with diesel engines)
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‒ Type "Z/C-B" = auxiliary heater (only for vehicles with petrol engines, not currently installed on the Audi A2)
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◆ Additional heater control is maintained during self-diagnosis.
Type "Z/C-D" heaters without recirculating pumps -V55 are fitted in vehicles with TDI engine as an additional heater. In its function as an additional heater, the heater is currently not equipped with a recirculating pump -V55.
The additional heater is switched on by the engine control as soon as the specified switch-on conditions have been satisfied.
Notes:
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◆ Depending on the country version of the vehicle and the engine, an electrical or fuel-powered additional heater is installed.
=> Audi sales range
=> Heating, Air Conditioner; Repair group 01
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◆ On vehicles with an electrical additional heater, the air is supplied with heat energy immediately after it exits from air-conditioner / heater heat exchanger.
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◆ On vehicles with 1.2 litre TDI engine with exhaust emissions standard "D4" (3 litre Öko for Germany) no additional heater is provided at this time.
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◆ On vehicles with 1.4 litre TDI engine for "cold countries" (e.g. Austria, Switzerland and all more northerly countries) no electric additional heater is currently installed. On these vehicles, a fuel-powered additional heater was or is installed, which supplies additional heat energy to the coolant.
=> Audi sales range
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◆ On vehicles with 1.4 litre TDI engine for "cold countries" an electric additional heater rated at approx. 1500 Watt will be installed as a running change starting from model year 2003. The fuel-powered additional heater will no longer be used on these vehicles once this fuel-powered additional heater is implemented.
=> Audi sales range
=> Heating, Air Conditioner; Repair group 01
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◆ On vehicles with a petrol engine, no additional heater is currently being provided.
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◆ Checking actuation of additional heater
=> Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System; Repair group 01
=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder
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◆ The operating and display unit -E87 / the heater control electronics actuates the engine control unit, which then decides whether the additional heater will be switched on. Depending on the engine control unit version, it is displayed in different measured value blocks of the engine control unit why the additional heater is not switched on or that it is being actuated.
=> Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System; Repair group 01
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◆ The engine control unit receives an additional heater request:
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‒ Via the data bus system on vehicles with air conditioner (convenience data bus and drive data bus).
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‒ On vehicles with heater via wiring from the heater control electronics to the engine control unit (the input in the heater control electronics is switched to earth).
=> Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System; Repair group 01
=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder
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◆ The fuel-powered additional heater is activated by the control unit for the diesel direct injection and glow plug system when certain conditions occur at the same time:
=> Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System; Repair group 01
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‒ The engine control unit will switch on the additional heater if the following conditions exist:
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‒ The operating and display unit -E87 transmits a request via the convenience data bus or the heater control electronics has switched input to earth (ECON button not pressed).
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‒ Engine speed is greater than 600 rpm.
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‒ The ambient temperature measured by the engine control unit is below 6°C (only on vehicles without air conditioner).
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‒ The coolant temperature is less than 70 °C (or less than 80°C at very low ambient temperatures).
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‒ Capacity utilisation of alternator -C is less than 60% (with electric additional heater only).
=> Heating, Air Conditioner; Repair group 01
=> Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System; Repair group 01
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