D83.70-0090-01
A71 Heater timer
S87 Stationary heater switch
S141 Heater booster switch
The hot water auxiliary heater B/D5W can be operated as a heater booster or as a stationary heater.
Heater booster mode
When the engine is running heater booster mode (indicator lamp in switch illuminated) can be switched on via the heater booster switch.
Stationary heater mode
The heater unit can be switched on with the stationary heater switch (indicator lamp in switch illuminated) or with the heater operating unit (option).
Note
If both switches are switched on stationary heater mode has priority over heater booster mode.
Heater booster mode is switched on automatically (only when the engine is running) at the end of stationary heater mode.
D83.70-0089-01
Operating the heater timer (option)
1 Time button
2 Preselector button
3 Button for heating without preselection
4 Reverse button
5 Advance button
6 Operating display
7 Current time or preselected time
8 Weekday or preselected day
9 Memory display
Note
All the symbols and numbers in the display flash after the voltage supply is connected.
The heater unit cannot be switched on in this condition.
The heater timer must be fully set first.
Setting the time of day and day of the week
Press button 1 until the display flashes. Set the current time of day with button 4 or 5. This is stored as soon as the display stops flashing. The day of the week then flashes. Set the current day of the week with button 4 or 5. This is stored as soon as the display stops flashing.
If only the time of day is to be adjusted, the flashing of the display and therefore the provision for adjusting the day of the week can be skipped after the time adjustment by pressing button 1 twice. Day of the week flashing can be shortened by pressing button 1 after adjusting the day of the week.
The display is retained when the ignition is "ON" and goes out after 15 seconds when the ignition is "OFF".
Switching on heater unit - with ignition "OFF"
Press button 3. The operating display and heating period are shown.
The heating period is set to 120 minutes at the plant and can be changed once or permanently.
Changing the heating period once - heater unit in operation
Shorten the heating period by pressing button 4 (up to a minimum of 1 minute).
Extend the heating period by pressing button 5 (up to a maximum of 120 minutes).
Changing the heating period permanently - heater unit not in operation
Press button 4 and hold down (approx. 3 seconds) until the display appears and flashes, then adjust heating period with button 4 or 5.
The new heating period is stored as soon as the display goes out.
Switching off heater unit
Press button 3. Operating display goes out.
Automatic run-on for cooling down.
Switching on heater unit - with ignition "ON"
Press button 3. Time of day, day of the week and operating display are shown. The heater remains in operation as long as the ignition is switched on.
If the ignition is switched off, there are 15 minutes remaining heating time, this can be extended to a maximum of 120 minutes by pressing button 5 or shortened to a minimum of 1 minute by pressing button 4.
Switching off heater unit
Press button 3. Operating display goes out.
Automatic run-on for cooling down.
Preselecting the start of heating
3 switching-on times can be stored. One of these switching-on times can be preselected within the next 24 hours or up to 7 days in advance.
Setting preselected times
Press button 2 until the desired memory location 1, 2 or 3 flashes in the display (no memory location number means neutral position). Press button 4 or 5 briefly and release. The preselected time will flash in the display. Adjust preselected time with button 4 or 5.
Setting is only possible if the preselected time is flashing in the display.
Neutral position - no memory is activated
Press button 2 until no memory location number is displayed
Preselecting the start of heating - within the next 24 hours
Press button 2 until the desired memory location 1, 2 or 3 and the preselected time flash in the display. If the display is not flashing any more, the preselected time is activated. The heater unit switches on at the preselected time displayed within the next 24 hours.
Note
Only one preselected time can be activated.
Preselecting the start of heating - after the next 24 hours
Press button 2 until the desired memory location 1, 2 or 3 and the preselected time flash in the display. After approx. 5 seconds the preselected day flashes in the display which can be adjusted with button 4 or 5. The preselected time and preselected day are stored and activated as soon as the current time of day is displayed. In addition to the current time of day, the memory location number and flashing heating symbol are displayed.
Note
Only one preselected time can be activated.
Switching on
When the heater unit is switched on (indicator lamp in switch is illuminated or operating display is shown in the heater timer) the vehicle's own heater blower is automatically switched on via the control module (stationary heater mode only). The coolant circulation pump is operated at the same time, the blower motor starts up for approx. 5 seconds and the glow pin is energized for 40 seconds.
Note
If there is still residual heat in the heat exchanger the blower motor runs alone (cold-blowing phase) until the residual heat is dissipated. Then the starting procedure commences.
Starting procedure
After preglow the fuel is delivered and ignited with the air supply. If a flame is detected, a changeover is made between two heat outputs depending on coolant temperature, with the quantity of fuel and air being adapted accordingly.
Closed-loop control in heating mode
The control module switches the heater unit to part load after the coolant temperature has reached approx. 80°C.
If the heat requirement is greater than the part load output of the heater unit, the heater unit switches back to full load at a coolant temperature of approx. 75°C. If the heat requirement is less than the part load output of the heater unit, the fuel supply is shut off at a coolant temperature of approx. 85°C.
The blower motor continues running for the run-on phase.
When the heat carrier cools down to approx. 75% the heater unit starts again and goes into full load mode.
The heater unit remains permanently in full load mode when there is a high heat requirement (heat requirement greater than or equal to 100% heat output).
Control/safety devices
A temperature-dependent resistance is built into the exhaust gas connection of the combustion chamber housing which takes over flame monitoring when starting and during operation. When a flame is formed, the control module detects the appropriate signal, completes the safety time of 90 seconds and switches off the glow pin.
A repeat start ensues if the safety time of 90 seconds has elapsed when the heater unit is started and the heater unit has not ignited. There is also a repeat start if the flame goes out during operation.
If there is no flame during the repeat start, the safety switch built into the control module switches off the heater unit permanently.
A renewed start can only take place if the heater unit is switched off and on again.
The heater unit is also shut down permanently (switching off with run-on) if the flame goes out more than twice within 10 minutes.
The overheating sensor responds in the event of overheating, e.g. due to a shortage of coolant or a badly bled coolant circuit. The fuel supply is interrupted and there is a fault shutdown. If the permissible number of 5 potential overheatings is exceeded, an operating lockout is triggered.
The heater unit can then only be enabled by the HHT.
Switching off
If the heater unit is switched off, a run-on occurs each time (120 seconds) in which the glow pin and blower motor are temporarily active. If the heater unit is switched off and immediately on again the run-on is completed in the correct sequence first of all.
Only then is the heater unit started again.