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Checking heat output
Note on vehicles with auxiliary heater (poor heat output)
If complaints are received about poor or inadequate heat output at low engine speeds on vehicles fitted with an auxiliary heater as optional extra, check actuation of auxiliary heater recirculating pump -V55 by additional heater control unit -J364.
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◆ Actuation of the recirculating pump -V55 increases the flow of coolant through the heating system heat exchanger at low engine speeds and thus improves heat output.
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◆ The additional heater control unit -J364 switches on the recirculating pump -V55 if it receives the following information via the convenience data bus:
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‒ Ignition on and engine running
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‒ Ambient temperature less than 20 °C
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‒ Engine speed less than 2000 rpm
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‒ Operating and display unit for air conditioner/Climatronic -E87 switched on ("OFF button" not pressed)
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‒ At least one of the two temperature flaps not on "cold" stop
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◆ Recirculating pump -V55 is switched on as soon as all cut-in conditions are met. To stop recirculating pump being constantly switched off and on, it remains activated for at least 30 s even if - for example in the event of rapid changes in vehicle speed - a request is only applied for several seconds (e.g. on accelerating after standing at traffic lights).
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◆ Incorporation of auxiliary heater (and recirculating pump -V55) into coolant circuit is described in
=> Auxiliary Heater; Repair Group 82
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◆ If vehicles with auxiliary heater and petrol engine are fitted with an operating and display unit for air conditioner/Climatronic -E87 with a hardware/software version as of "XX15" (index "D" onwards), they must not be equipped with an auxiliary heater control unit (additional heater control unit -J364) with hardware/software version "XX09". Such a combination can lead to problems with actuation of recirculating pump -V55 when engine is running. This problem is no longer encountered with additional heater control units -J364 as of hardware/software version "XX10".
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◆ As of Model Year 2003, operating and display units for air conditioner/Climatronic -E87 with part number as of index "D" (with hardware/software version as of "XX15") are gradually being introduced. With this -E87 version, the passenger compartment temperature regulation is designed to be somewhat cooler.
=> Parts List
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◆ Vehicles with 4-cyl. petrol direct injection engine (FSI) are only to be fitted with operating and display units for air conditioner/Climatronic -E87 with part number as of index "D".
=> Parts List
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