| A = ON signal for auxiliary heater (supplementary heater) |
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| The auxiliary heater control unit -J364- receives the request for activation as auxiliary heater (or supplementary heater) via the convenience data bus. |
| a = Component check (approx. 2 seconds) |
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| The auxiliary heater control unit -J364- checks the connected components |
| b = Pre-heating time (approx. 6 seconds) |
| c = Pre-heating and ventilation (approx. 7 seconds) |
| D = Start of fuel delivery |
| d = Start and flame formation (max. 90 seconds) |
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| If no flame is detected, the auxiliary heater control unit -J364- terminates the starting procedure. On completion of the run-on time stored in the auxiliary heater control unit -J364-, the auxiliary heater control unit -J364- attempts a second start. If there is again no flame, the auxiliary heater control unit -J364- switches to fault status. |
| e = Safety margin (approx. 6 seconds) |
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| For flame stabilisation |
| F = Start of full load operation |
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| Full load operation (duration temperature-dependent) |
| f 1 = The coolant temperature in the auxiliary heater reaches 30 °C (up to 45 °C depending on the version of the auxiliary heater control unit -J364-) and, in auxiliary heating mode, the operating and display unit, Climatronic control unit -J255- of the air conditioner/heater is requested by way of the convenience data bus system to switch on the fresh air blower -V2-. |
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| At the start of full load operation, the heater coolant shut-off valve -N279- is actuated and, given a low coolant temperature, the coolant circuit is switched to the small circuit. |
| f 2 = The coolant temperature in the auxiliary heater reaches 71 °C, the auxiliary heater control unit -J364- alters actuation of the heater coolant shut-off valve -N279- → Chapter |
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