| Checking of heated rear window -Z1- |
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| If a condition exists which prevents activation of the heated rear window (short circuit in connection to rear window or to heated rear window relay -J9-, open circuit in power supply to operating and display unit, Climatronic control unit -J255- or open convertible top with Cabrio), the indicator lamp in the button lights on pressing the button in the operating and display unit, Climatronic control unit -J255- and goes out again on releasing the button, however the heating is not activated. |
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| If the voltage measured by the operating and display unit, Climatronic control unit -J255- at terminal “30” drops below 12.5 V, the power of the heated rear window is reduced, thus relieving the load on the alternator (the electronic system of the operating and display unit, Climatronic control unit -J255- reduces the actuation duty cycle from 100% to 90....10%). |
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| On vehicles up to chassis number “399999” in Model Year 2005 (Saloon and Avant) and “012912” in Model Year 2005 (Cabrio) → Parts catalogue, the heated rear window -Z1- is actuated directly by the operating and display unit, Climatronic control unit -J255- (the relay which switches the current is fitted in the operating and display unit, Climatronic control unit -J255-) |
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| On vehicles as of chassis number “400000” in Model Year 2005 (Saloon and Avant) and “012913” in Model Year 2005 (Cabrio) → Parts catalogue, the heated rear window -Z1- is no longer actuated directly by the operating and display unit, Climatronic control unit -J255- (the operating and display unit, Climatronic control unit -J255- with part number as of index “AJ” is not fitted with a relay). On these vehicles, the heated rear window -Z1- is actuated by way of the heated rear window relay -J9-. |
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| At ambient temperatures below 0 °C, the heated rear window remains switched on until the ignition is switched off (manual deactivation is possible at any time). If the temperature during a driving cycle rises above 0 °C, the heated rear window -Z1- is deactivated on completion of the operating period stored in the operating and display unit, Climatronic control unit -J255- (approx. 12 minutes). |
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| At ambient temperatures greater than 0 °C, actuation of the heated rear window -Z1- is terminated automatically on completion of the operating period (approx. 12 minutes) stored in the operating and display unit, Climatronic control unit -J255- by way of the operating and display unit, Climatronic control unit -J255-. |
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