S83.70-4689-79
A1/1 | Instrument cluster (KI) control unit | N33/3m1 | Stationary heater combustion air blower | |
A2/129 | Communications module/stationary heater antenna (with CODE HY1 (Radio remote control for auxiliary heater)) | N33/3n1 | Stationary heater unit | |
A8/2 | Warm water stationary heater radio remote control transmitter (with CODE HY1 (Radio remote control for auxiliary heater)) | N33/3r1 | Stationary heater glow plug/flame monitor unit | |
A40 | Central operating unit (COU [ZBE]) control unit | N73 | Electronic ignition lock (EZS) control unit | |
A40/8 | Audio/COMAND display control unit | N87/6 | Radio (Audio/COMAND) | |
A49/5 | Water stationary heater radio remote control receiver (with CODE HY1 (Radio remote control for auxiliary heater)) | N93/4 | Gateway for user interface CAN | |
B14 | Outside temperature sensor | N154 | Automatic air conditioning (KLA) control unit | |
M2 | Blower motor | S98/1 | Front heater/air conditioning operating unit switch | |
M9 | Blower with interior air temperature sensor | S98/1s12 | Stationary heater button | |
M9b1 | Interior air temperature sensor | Y141 | Stationary heater switchover valve | |
M13/3 | Heater coolant circulation pump | X11 | Diagnostic connector | |
M46/1 | STH fuel metering pump | CAN A | Telematics CAN | |
N2/18 | Supplemental restraint system (SRS) control unit | CAN B | Interior CAN | |
N3/33 | CDI control unit | CAN E | Chassis CAN | |
N10/1 | Signal acquisition and actuation module (SAM) control unit | CAN HMI | User interface CAN | |
N33/3 | Hot water stationary heater (STH) control unit | LIN B8 | Climate control LIN | |
N33/3b1 | Stationary heater temperature sensor | LIN B8-1 | Climate control LIN 1 | |
N33/3f1 | Stationary heater thermal fuse |
Auxiliary heater, general
The auxiliary heater ensures that the vehicle interior is temperature-controlled and that the windows are clear of ice and fogging before setting off during the colder seasons. Operation of the auxiliary heater therefore reduces the risk of accidents by providing clear view when setting off.
The auxiliary heater can be switched on as follows:
With the stationary heater button (S98/1s12)
With the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater))
Preprogrammed by activating a departure time
With code HY1 (Radio remote control for auxiliary heater)
The water stationary heater radio remote control receiver (A49/5) saves the current operating status for the auxiliary heater. The automatic air conditioning (AAC) control unit (N154) continuously receives information about the status of the auxiliary heater from the warm water stationary heater (STH) control unit (N33/3) via the climate control LIN (LIN B8) and transmits this via the climate control LIN (LIN B8) to the water stationary heater radio remote control receiver (A49/5). The information can be queried here via the warm water stationary heater radio remote control transmitter (A8/2).
The main component of the auxiliary heater is the stationary heater unit (N33/3n1). It contains all components necessary to generate heat. The stationary heater unit (N33/3n1) is directly integrated in the heating and cooling circuit of the engine and is supplied with fuel by the stationary heater fuel metering pump (M46/1). As the master of the auxiliary heater, the automatic air conditioning (AAC) control unit (N154) evaluates all variables and communicates with the warm water stationary heater (STH) control unit (N33/3) via the climate control LIN (LIN B8). The automatic air conditioning (AAC) control unit (N154) transmits the "Heat" request via the climate control LIN (LIN B8) to the warm water stationary heater (STH) control unit (N33/3) to trigger heating operation.
Operation of the auxiliary heater requires determination of the following temperatures:
Outside temperature
The outside temperature is detected by the outside temperature sensor (B14). The signal acquisition and actuation module (SAM) control unit (N10/1) reads in the signal directly, calculates the outside temperature and transmits this via the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154). The automatic air conditioning (AAC) control unit (N154) forwards the signal via the interior CAN (CAN B), the electronic ignition lock (EZS)control unit (N73), the chassis CAN (CAN E), the gateway for user interface CAN (N93/4) and the user interface CAN (CAN HMI) to the instrument cluster (IC) control unit (A1/1).
Interior temperature
The interior temperature is recorded via the interior air temperature sensor (M9b1) by the automatic air conditioning (AAC) control unit (N154). The interior air temperature sensor (M9b1) is integrated into the fan with the interior air temperature sensor (M9). The automatic air conditioning (AAC) control unit (N154) transmits the interior temperature via the interior CAN (CAN B) to the signal acquisition and actuation module (SAM) control unit (N10/1).
The auxiliary heater function includes the following subfunctions:
Electrical function sequence, teaching in the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater))
Electrical function sequence, departure time programming
Electrical function sequence for activating heating operation for departure time
Electrical function sequence for triggering immediate mode
Electrical function sequence for activation of heater booster mode
Electrical function sequence, teaching in the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater))
The individual components of the auxiliary heater have already been tuned to each other in the factory. Teaching in is only necessary when replacing the water stationary heater radio remote control receiver (A49/5) or the warm water stationary heater radio remote control transmitter (A8/2).
To teach in the warm water stationary heater radio remote control transmitter (A8/2), the stationary heater button (S98/1s12) in the FRONT heater/air conditioning operating unit switch (S98/1) must be pressed for approx. 20 s. The FRONT heater/air conditioning operating unit switch (S98/1) evaluates the status of the stationary heater button (S98/1s12) and transmits this via the climate control LIN (LIN B8) to the automatic air conditioning (AAC) control unit (N154). The automatic air conditioning (AAC) control unit (N154) transmits the request to open the teach-in period window via the climate control LIN (LIN B8) to the water stationary heater radio remote control receiver (A49/5). The water stationary heater radio remote control receiver (A49/5) then opens the teach-in period window for a maximum of 5 s. When the teach-in period window is open, the automatic air conditioning (AAC) control unit (N154) actuates the LED of the stationary heater button (S98/1s12) in the FRONT heater/air conditioning operating unit switch (S98/1) via the climate control LIN (LIN B8).
If the red LED in the stationary heater button (S98/1s12) is flashing, the "OFF" button on the warm water stationary heater radio remote control transmitter (A8/2) must be pressed until the display in the warm water stationary heater radio remote control transmitter (A8/2) is indicating "OFF".
The warm water stationary heater radio remote control transmitter (A8/2) then transmits a signal. The water stationary heater radio remote control receiver (A49/5) receives the signal via the communications module/stationary heater antenna (A2/129). The water stationary heater radio remote control receiver (A49/5) saves the warm water stationary heater radio remote control transmitter (A8/2) as being assigned to it.
The water stationary heater radio remote control receiver (A49/5) then closes the teach-in period window. To teach in another warm water stationary heater radio remote control transmitter (A8/2), the teach-in period window must be re-opened.
The water stationary heater radio remote control receiver (A49/5) can store up to 3 warm water stationary heater radio remote control transmitters (A8/2). If a 4th warm water stationary heater radio remote control transmitter (A8/2) is taught in, the 1st warm water stationary heater radio remote control transmitter (A8/2) that was taught in will be overwritten.
The teach-in period window can be opened using the diagnostic system via the diagnostic connector (X11), its duration can be configured, and the number of teach-in procedures can be read out.
Electrical function sequence, departure time programming
The departure time can be set, selected and activated via the "Climate control" menu in the central operating unit (COU) control unit (A40) or via the warm water stationary heater radio remote control transmitter (A8/2).
The "Climate control" menu is displayed to the driver on the Audio/COMAND display control unit (A40/8). Up to 3 departure times can be configured. If a departure time has been activated, the yellow LED in the stationary heater button (S98/1s12) illuminates.
To do this, the central operating unit (COU) control unit (A40) transmits the "Pre-set time activated" status via the telematics CAN (CAN A) to the Audio/COMAND display control unit (A40/8) and via the telematics CAN (CAN A), the radio (Audio/COMAND) (N87/6), the user interface CAN (CAN HMI), the gateway for user interface CAN (N93/4), the chassis CAN (CAN E), the electronic ignition lock control unit (EZS) (N73) and the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154).
The automatic air conditioning (AAC) control unit (N154) actuates the yellow LED in the stationary heater button (S98/1s12) via the climate control LIN (LIN B8) and the FRONT heater/air conditioning operating unit switch (S98/1).
Activating the departure time using the "Climate control" menu on the radio (Audio/COMAND) (N87/6):
The user can set, select or activate the required departure time using the controls of the central operating unit (COU) control unit (A40). The relevant requests for selecting the departure time are transmitted by the central operating unit (COU) control unit (A40) via the telematics CAN (CAN A) to the Audio/COMAND display control unit (A40/8). The operating requests are graphically displayed in the Audio/COMAND display control unit (A40/8). The Audio/COMAND display control unit (A40/8) generates the relevant picture data. At the same time, the selected settings are transmitted by the Audio/COMAND display control unit (A40/8) via the radio (Audio/COMAND) (N87/6), the user interface CAN (CAN HMI), the gateway for user interface CAN (N93/4), the chassis CAN (CAN E), the electronic ignition lock (EZS) control unit (N73) and the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154).
The automatic air conditioning (AAC) control unit (N154) then transmits a message about the activated departure time via the interior CAN (CAN B), the electronic ignition lock (EZS) control unit (N73), the chassis CAN (CAN E), the gateway for user interface CAN (N93/4) and the user interface CAN (CAN HMI) to the instrument cluster (IC) control unit (A1/1), which saves this.
Activating the departure time with the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater))
To select a departure time, one of the arrow keys must be pressed. The 1st of 3 possible departure times is now displayed. If one of the arrow buttons is pressed again, the 2nd departure time is displayed. Pressing the key again displays the 3rd departure time.
The displayed departure time can be programmed in configuration mode. The "ON" and "OFF" buttons on the warm water stationary heater radio remote control transmitter (A8/2) must be pressed simultaneously to do this. The clock symbol in the display of the warm water stationary heater radio remote control transmitter (A8/2) flashes. The departure time can now be set using the arrow keys. To accept the new departure time setting, the "ON" and "OFF" buttons on the warm water stationary heater radio remote control transmitter (A8/2) must be pressed simultaneously again.
To activate a departure time, press the "ON" button on the warm water stationary heater radio remote control transmitter (A8/2) after calling up the required departure time. The warm water stationary heater radio remote control transmitter (A8/2) transmits an appropriate signal. The water stationary heater radio remote control receiver (A49/5) receives the signal via the communications module/stationary heater antenna (A2/129). The water stationary heater radio remote control receiver (A49/5) transmits this via the climate control LIN (LIN B8) to the automatic air conditioning (AAC) control unit (N154).
The automatic air conditioning (AAC) control unit (N154) then transmits a message about the activated departure time via the interior CAN (CAN B), the electronic ignition lock (EZS) control unit (N73), the chassis CAN (CAN E), the gateway for user interface CAN (N93/4) and the user interface CAN (CAN HMI) to the instrument cluster (IC) control unit (A1/1), where it is saved.
To deactivate a departure time, the "OFF" button must be pressed on the warm water stationary heater radio remote control transmitter (A8/2) after calling up the required departure time. The operating condition of the auxiliary heater is shown on the display of the warm water stationary heater radio remote control transmitter (A8/2).
The display duration can be set to between 4 and 30 s in 2-second intervals.
Electrical function sequence for activating heating operation for departure time
Ventilation or heating mode can be triggered immediately or preprogrammed:
Triggering via the stationary heater button (S98/1s12)
Triggering via the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater))
Triggering when the starting time has been reached (departure time activated)
Triggering via the stationary heater button (S98/1s12)
Ventilation or heating mode is requested by pressing the stationary heater button (S98/1s12) in the FRONT heater/air conditioning operating unit switch (S98/1). The FRONT heater/air conditioning operating unit switch (S98/1) reads in the status of the stationary heater button (S98/1s12) directly and transmits this via the climate control LIN (LIN B8) to the automatic air conditioning (AAC) control unit (N154). The automatic air conditioning (AAC) control unit (N154) decides whether heating or ventilation is required after comparing the specified and the actual interior temperature.
Triggering via the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater))
Ventilation or heating mode is requested by pressing the "ON" button on the warm water stationary heater radio remote control transmitter (A8/2) for 1.5 s. The warm water stationary heater radio remote control transmitter (A8/2) transmits an appropriate signal (activation signal). The water stationary heater radio remote control receiver (A49/5) receives the signal via the communications module/stationary heater antenna (A2/129) and transmits this via the climate control LIN (LIN B8) to the automatic air conditioning (AAC) control unit (N154). The automatic air conditioning (AAC) control unit (N154) decides whether heating or ventilation is required after comparing the specified and the actual interior temperature.
The maximum range of the warm water stationary heater radio remote control transmitter (A8/2) is 300 m (outdoors). The following influences can reduce the maximum range:
Radio interference
Solid obstacles (e.g. enclosed rooms)
Unfavorable position in relation to vehicle
If the radio signal does not reach the water stationary heater radio remote control receiver (A49/5), this is indicated on the display of the warm water stationary heater radio remote control transmitter (A8/2).
Triggering when the starting time has been reached (departure time activated)
Approx. 60 min before the activated departure time, the instrument cluster (IC) control unit (A1/1) requests the ventilation or heating duration that is required to reach the set specified temperature via the user interface CAN (CAN HMI), the gateway for user interface CAN (N93/4), the chassis CAN (CAN E), the electronic ignition lock (EZS) control unit (N73) and the interior CAN (CAN B) from the automatic air conditioning (AAC) control unit (N154). The automatic air conditioning (AAC) control unit (N154) decides whether heating or ventilation is required after comparing the specified and the actual interior temperature.
The automatic air conditioning (AAC) control unit (N154) transmits the required ventilation or heating duration via the interior CAN (CAN B), the electronic ignition lock (EZS) control unit (N73), the chassis CAN (CAN E), the gateway for user interface CAN (N93/4) and the user interface CAN (CAN HMI) to the instrument cluster (IC) control unit (A1/1), which calculates the switch-on time from the ventilation or heating duration and the current time. When the switch-on time is reached, the instrument cluster (IC) control unit (A1/1) transmits the request for ventilation or heating via the user interface CAN (CAN HMI), the gateway for user interface CAN (N93/4), the chassis CAN (CAN E), the electronic ignition lock (EZS) control unit (N73) and the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154).
A switch-on signal that has been transmitted by the instrument cluster (IC) control unit (A1/1) because of an activated departure time is ignored if ventilation or heating mode has been activated manually in the meantime.
Additional electrical function requirements for triggering immediate mode
Ventilation or heating mode request present
Remaining fuel quantity above minimum fill level
No undervoltage or overvoltage
When circuit 15 is switched off, the warm water stationary heater control unit (STH) (N33/3) stores the fuel level. The instrument cluster (IC) control unit (A1/1) transmits the "Fuel level" signal via the user interface CAN (CAN HMI), the gateway for user interface CAN (N93/4), the chassis CAN (CAN E), the electronic ignition lock (EZS) control unit (N73) and the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154).
The circuit 15 status is sent by the electronic ignition lock (EZS) control unit (N73) over the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154).
Electrical function sequence for triggering immediate mode
When ventilation or heating mode is activated, the status of all components involved in heating mode is queried first. The automatic air conditioning (AAC) control unit (N154) transmits a status inquiry via the climate control LIN (LIN B8) to the warm water stationary heater (STH) control unit (N33/3). The warm water stationary heater (STH) control unit (N33/3) then transmits its status via the climate control LIN (LIN B8) to the automatic air conditioning (AAC) control unit (N154). If a fault is detected, heating mode is not started. The fault that has been detected is verified by means of a self-test. The result of this self-test updates the status so that heating can take place when the next switch-on attempt occurs, depending on the result. Ventilation mode can always be activated, regardless of the test result.
The following components are tested when starting and in heating mode for any open circuits, short circuits and proper operation:
STH fuel metering pump (M46/1)
Stationary heater temperature sensor (N33/3b1)
Stationary heater thermal fuse (N33/3f1)
Stationary heater combustion air blower (N33/3m1)
Stationary heater glow plug/flame monitor unit (N33/3r1)
Stationary heater switchover valve (Y141)
A stationary heater switchover valve (Y141) defect neither interrupts heating mode nor prevents it from starting up, because this component is not relevant for safe operation of the auxiliary heater.
Triggering via the stationary heater button (S98/1s12)
Heating mode is requested by pressing the stationary heater button (S98/1s12). The FRONT heater/air conditioning operating unit switch (S98/1) reads in the status of the stationary heater button (S98/1s12) directly and transmits this via the climate control LIN (LIN B8) to the automatic air conditioning (AAC) control unit (N154). The automatic air conditioning (AAC) control unit (N154) decides whether heating or ventilation is required after comparing the specified and the actual interior temperature.
Triggering via the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater))
Ventilation or heating mode is requested by pressing the "ON" button on the warm water stationary heater radio remote control transmitter (A8/2) for 1.5 s. The warm water stationary heater radio remote control transmitter (A8/2) transmits an appropriate signal (switch-on signal). The water stationary heater radio remote control receiver (A49/5) receives the signal via the communications module/stationary heater antenna (A2/129) and transmits it via the climate control LIN (LIN B8) to the automatic air conditioning (AAC) control unit (N154). The automatic air conditioning (AAC) control unit (N154) decides whether heating or ventilation is required after comparing the specified and the actual interior temperature.
After 2 s, the automatic air conditioning (AAC) control unit (N154) transmits the "Heating" request via the climate control LIN (LIN B8) to the warm water stationary heater (STH) control unit (N33/3), which implements this request accordingly. The LED in the stationary heater button (S98/1s12) indicates the operating mode:
Ventilation mode, the blue LED illuminates
Heating mode, the red LED illuminates
To do this, the automatic air conditioning (AAC) control unit (N154) transmits the "Stationary heater or stationary ventilation active" status via the climate control LIN (LIN B8) to the FRONT heater/air conditioning operating unit switch (S98/1), which actuates the LED in the stationary heater button (S98/1s12) accordingly.
Ventilation mode
In ventilation mode, the automatic air conditioning (AAC) control unit (N154) actuates the blower motor (M2) via climate control LIN 1 (LIN B8-1). With the basic setting, the maximum ventilation time is 30 min. The ventilation time can be modified to between 10 and 60 min in 10 minute intervals via the diagnostic system.
Ventilation mode can be stopped manually via the stationary heater button (S98/1s12) in the FRONT heater/air conditioning operating unit switch (S98/1) or via the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater)).
With "Circuit 15 ON" the blower motor (M2) is actuated directly depending on the setting selected on the automatic air conditioning (AAC) control unit (N154). Ventilation mode goes into the background. The LED in the stationary heater button (S98/1s12) continues to illuminate in blue.
Heating mode
The warm water stationary heater (STH) control unit (N33/3) starts heating mode by actuating the stationary heater combustion air blower (N33/3m1) in the stationary heater unit (N33/3n1). The glow plug in the stationary heater glow plug/flame monitor unit component (N33/3r1) is switched on. The preheating time of approx. 30 s starts. After the preglow time has elapsed, the stationary heater fuel metering pump (M46/1) starts to deliver fuel. The stationary heater fuel metering pump (M46/1) is actuated by the warm water stationary heater (STH) control unit (N33/3) via climate control LIN 1 (LIN B8-1). The fuel, which evaporates on a metallic mesh in the burner housing, forms a fuel/air mixture together with the combustion air. This fuel/air mixture is ignited by the glow plug, and a flame is formed. The glow plug then becomes a flame monitor. The stationary heater combustion air blower (N33/3m1) and the stationary heater fuel metering pump (M46/1) increase their rotational speed and output to full load within 60 s.
During heating operation the stationary heater glow plug/flame monitor unit component (N33/3r1) signals the following in its function as a flame monitor:
"Hot" = sufficient combustion
Heating mode continues. Depending on the interior temperature, a switchover from heating mode to ventilation mode or vice versa can take place.
"Cold" = no flame
Flame-out or insufficient flame formation, the stationary heater fuel metering pump (M46/1) is shut off and a repeat startup is initiated once. If flame formation is still not possible, the stationary heater fuel metering pump (M46/1) is shut off and the emergency shutoff is activated with stationary heater combustion air blower (N33/3m1) after-run.
Following the "Heat" decision, the automatic air conditioning (AAC) control unit (N154) actuates the heater coolant circulation pump (M13/3) directly. The coolant is heated in the stationary heater unit (N33/3n1). When a coolant temperature of 50 °C is reached in the stationary heater unit (N33/3n1), the automatic air conditioning (AAC) control unit (N154) actuates the blower motor (M2) via climate control LIN 1 (LIN B8-1). The coolant temperature in the stationary heater unit (N33/3n1) is detected by the stationary heater temperature sensor (N33/3b1).
The warm water stationary heater control unit (STH) (N33/3) reads in the signal of the stationary heater temperature sensor (N33/3b1) directly.
The automatic air conditioning (AAC) control unit (N154) transmits the request for actuation of the stationary heater switchover valve (Y141) via the climate control LIN (LIN B8) to the warm water stationary heater (STH) control unit (N33/3). The warm water stationary heater (STH) control unit (N33/3) actuates the stationary heater switchover valve (Y141) via climate control LIN 1 (LIN B8-1).
Heating operation is regulated via the following power levels dependent on the coolant temperature from the warm water stationary heater (STH) control unit (N33/3):
"POWER" (5 kW at less than 65 °C)
"HIGH" (3.5 kW at 65 to 70 °C)
"LOW" (2.1 kW at 70 to 75 °C)
Heating operation is interrupted at a coolant temperature of more than 75 °C and reactivated when the temperature drops below 65 °C.
After reaching the departure time, the auxiliary heater remains switched on for 5 min and then automatically switches off. Unless the engine is started, in which case the auxiliary heater operates in heater booster mode until it is switched off manually or the coolant temperature at the auxiliary heater exceeds 75 °C or the driving cycle is completed (no time limit).
In auxiliary heater heating mode the stationary heater switchover valve (Y141) in the coolant circuit is actuated in such a way that the full heating power of the auxiliary heater is available for the vehicle interior, and the engine is bypassed. If the engine is started during auxiliary heater heating mode, the stationary heater switchover valve (Y141) does not enable the extended coolant circuit via the engine until the difference between the coolant temperature at the outlet of the auxiliary heater and the coolant temperature in the engine drops below 5 °C (avoids vehicle interior heater temperature drop).
Stopping ventilation or heater operation
Heating mode can be stopped manually via the stationary heater button (S98/1s12) in the FRONT heater/air conditioning operating unit switch (S98/1) or via the warm water stationary heater radio remote control transmitter (A8/2) (with code HY1 (Radio remote control for auxiliary heater)).
Ventilation or heating mode can also be stopped automatically. For this purpose, the warm water stationary heater (STH) control unit (N33/3) continuously monitors the operation of all components involved. Ventilation or heating mode is stopped automatically under the following conditions:
Overheating of the stationary heater unit (N33/3n1)
Undervoltage
Crash
Overheating of the stationary heater unit (N33/3n1)
When a temperature of 125 °C is exceeded in the stationary heater unit (N33/3n1), the auxiliary heater is switched off with a subsequent overheating interlock. The temperature in the stationary heater unit (N33/3n1) is detected by the stationary heater temperature sensor (N33/3b1). The signals of the stationary heater temperature sensor (N33/3b1) are read in directly by the warm water stationary heater (STH) control unit (N33/3). The warm water stationary heater (STH) control unit (N33/3) switches off the auxiliary heater.
For additional protection, the stationary heater thermal fuse (N33/3f1) is triggered at a temperature of 145 °C. The auxiliary heater is no longer supplied with fuel.
After shutoff, the stationary heater button (S98/1s12) must be pressed for 5 to 15 s to restart. Then the stationary heater thermal fuse (N33/3f1) must be removed within 30 s and then inserted again.
Undervoltage
If the on-board electrical system voltage drops below 11.8 V, the automatic air conditioning (AAC) control unit (N154) switches off the auxiliary heater. The signal acquisition and actuation module (SAM) control unit (N10/1) transmits the signal for shutting off the auxiliary heater via the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154). If the auxiliary heater is on, the automatic air conditioning (AAC) control unit (N154) activates the "Emergency shutoff" and transmits the "Heating 0 %" request via the climate control LIN (LIN B8) to the warm water stationary heater (STH) control unit (N33/3). The stationary heater unit (N33/3n1) is then permanently switched off.
Crash
In the event of an accident, the auxiliary heater is automatically turned off to reduce the risk of fire. The supplemental restraint system (SRS) control unit (N2/18) transmits the crash signal via the chassis CAN (CAN E), the electronic ignition lock (EZS) control unit (N73) and the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154). If the auxiliary heater is on, the automatic air conditioning (AAC) control unit (N154) activates the "Emergency shutoff" and transmits the "Heat 0 %" request via the climate control LIN (LIN B8) to the warm water stationary heater (STH) control unit (N33/3). The stationary heater unit (N33/3n1) is then permanently switched off. The shutoff can only be reset using the diagnostic system.
Additional electrical function requirements for activation of heater booster mode
"Drivetrain operational" signal set
Coolant temperature is lower than the shut-off limit set via the diagnostic system
The CDI control unit (N3/33) transmits the "Drivetrain operational" signal via the chassis CAN (CAN E), the electronic ignition lock unit (EZS) control unit (N73) and the interior CAN (CAN B) to the automatic air conditioning (AAC) control unit (N154).
Electrical function sequence for activation of heater booster mode
The user has the option of activating heater booster mode manually by pressing the stationary heater button (S98/1s12).
The FRONT heater/air conditioning operating unit switch (S98/1) reads in the status of the stationary heater button (S98/1s12) directly and transmits the signal via the climate control LIN (LIN B8) to the automatic air conditioning (AAC) control unit (N154). The automatic air conditioning (AAC) control unit (N154) then transmits the "Heating" request via the climate control LIN (LIN B8) to the warm water stationary heater control unit (STH) (N33/3).
At an outside temperature of -9 °C, the auxiliary heater starts heater booster mode automatically. The automatic air conditioning (AAC) control unit (N154) transmits the "Stationary heater button LED" request to the FRONT heater/air conditioning operating unit switch (S98/1). The FRONT heater/air conditioning operating unit switch (S98/1) activates the red LED in the stationary heater button (S98/1s12). Automatic heater booster mode remains active until the outside temperature rises above -8 °C again or until the auxiliary heater is switched off manually or the driving cycle is stopped.
The warm water stationary heater (STH) control unit (N33/3) starts stationary heater unit (N33/3n1) heater booster mode . At the same time, the automatic air conditioning (AAC) control unit (N154) actuates the heater coolant circulation pump (M13/3) directly. The coolant of the large coolant circuit is then circulated.
Heater booster mode activity is signaled by illumination of the red LED in the stationary heater button (S98/1s12). The automatic air conditioning (AAC) control unit (N154) transmits the request to switch on the LED via the climate control LIN (LIN B8) to the FRONT heater/air conditioning operating unit switch (S98/1). The FRONT heater/air conditioning operating unit switch (S98/1) actuates the LED directly.
Heater booster mode
The warm water stationary heater (STH) control unit (N33/3) starts heater booster mode by actuating the stationary heater combustion air blower (N33/3m1) in the stationary heater unit (N33/3n1). The glow plug in the stationary heater glow plug/flame monitor unit component (N33/3r1) is switched on. The preheating time of approx. 30 s starts. After the preglow time has elapsed, the stationary heater fuel metering pump (M46/1) starts to deliver fuel. The stationary heater fuel metering pump (M46/1) is actuated by the warm water stationary heater (STH) control unit (N33/3) via climate control LIN 1 (LIN B8-1). The fuel, which evaporates on a metallic mesh in the burner housing, forms a fuel/air mixture together with the combustion air. This fuel/air mixture is ignited by the glow plug, and a flame is formed. The glow plug then becomes a flame monitor. The stationary heater combustion air blower (N33/3m1) and the stationary heater fuel metering pump (M46/1) increase their rotational speed and output to full load within 60 s.
During heater booster mode the stationary heater glow plug/flame monitor component (N33/3r1) signals the following in its function as a flame monitor:
"Hot" = sufficient combustion
Heater booster mode continues.
"Cold" = no flame
Flame-out or insufficient flame formation, the stationary heater fuel metering pump (M46/1) is shut off and a repeat startup is initiated once. If flame formation is still not possible, the stationary heater fuel metering pump (M46/1) is shut off and the emergency shutoff is activated with stationary heater combustion air blower (N33/3m1) after-run.
The coolant is heated in the stationary heater unit (N33/3n1). The coolant temperature in the stationary heater unit (N33/3n1) is detected by the stationary heater temperature sensor (N33/3b1).
The warm water stationary heater (STH) control unit (N33/3) reads in the signals of the stationary heater temperature sensor (N33/3b1) directly.
The automatic air conditioning (AAC) control unit (N154) transmits the request for actuation of the stationary heater switchover valve (Y141) via the climate control LIN (LIN B8) to the warm water stationary heater (STH) control unit (N33/3). The warm water stationary heater (STH) control unit (N33/3) actuates the stationary heater switchover valve (Y141) via climate control LIN 1 (LIN B8-1).
Electrical function schematic, teach-in of stationary heater radio remote control transmitter | With code HY1 (Radio remote control for auxiliary heater) | ||
Electrical function schematic, programming departure time | |||
Electrical function schematic, trigger heating mode for departure time | |||
Electrical function schematic, trigger immediate mode | |||
Electrical function schematic for triggering heater booster mode | |||
Overview of system components for auxiliary water heater |