Stationary Heater Switch Activation of Heater Operation

Stationary Heater Switch Activation Of Heater Operation

Shown On Models 215, 220:

Operating procedure
1 Basic requirements:
- Ignition (terminal 15) OFF.

2 The STH switch (N72s12 or S46) has been actuated for longer than 2 s and the "Stationary heater ON" signal has been triggered.

3 The "Stationary heater ON" signal is forwarded directly to the STH or heater booster control module (A6n1).

4 The STH or heater booster control module (A6n1) recognizes the cut-in signal:
- Via the interior CAN Class B (CAN-B), it activates the menu for the stationary heater in the multifunction display in the instrument cluster (A1) and
- simultaneously starts the heat or ventilate inquiry in the operating and control module (N18, N22 or N22/7).

5 The operating and control module (N18, N22 or N22/7) activates, if present, the display field and compares the current in-car temperature with the preset temperature value.

6.1 Interior temperature < preset temperature value:
- The operating and control module (N18, N22 or N22/7) transmits the "Heat" signal to the STH or heater booster control module (A6n1) via CAN Class B (CAN-B) and switches to stationary heating mode. The heat symbol is activated in the display field.
- The STH or heater booster control module (A6n1) activates heater operation:
- The green or red indicator lamp in the emergency STH control switch (N72s12 or S46) indicates the fact that heater operation is active by being permanently illuminated.

6.2 Interior temperature > preset temperature value:
- The operating and control module (N18, N22 or N22/7) transmits the "Heat" signal to the STH or heater booster control module (A6n1) via CAN Class B (CAN-B) and switches to stationary ventilation mode. The fan symbol is activated in the display field.
- The STH or heater booster control module (A6n1) initializes stationary ventilation and transmits the "Fan on" signal to the HEAT or AAC operating and control module.
- The green or red malfunction indicator lamp in the STH switch (N72s12 or S46) indicates that stationary ventilation is active by flashing on and off.

Ignition (terminal 15) ON
- With the ignition switched on the STH or heater booster control module (A6n1) starts the heat or ventilate inquiry in the operating and control module (N18, N22 or N22/7) after heater operation has been triggered, as it does with the ignition switched off.
- In this case the control and operating module (N18, N22 or N22/7) picks up the STH or heater booster control module (A6n1) signal in the back ground, always replies with the "Heat" signal and continues with its normal operating mode.
- When the ignition is switched off and heater operation continues to remain active, the signal acquired in the back ground causes the operating and control module (N18, N22 or N22/7) to change modes automatically. The operating and control module (N18, N22 or N22/7) then switches to stationary heating mode or stationary ventilation according to the interior temperature. The output of a further signal by the STH or heater booster control module (A6n1) is therefore no longer necessary.