Stationary Heater, Basic Function - GF83.70-P-9900A
MODEL ALL (CAR) with code 228 (Auxiliary heater)
Overview
This document contains information on:
- General
- Function requirements
- Check function
- Ventilation function
- Heating function
- Ventilation/heating mode triggered after entering departure time
General
The stationary heater can also be used for vehicle interior temperature control or ventilation even when the vehicle has been switched off. The heater is the central component part of the stationary heater. It is connected to the engine's coolant circuit and it contains all the component parts required for heat generation, including the stationary heater control unit.
A fuel pump supplies the heater with the required fuel. The fuel is burnt in the combustion chamber and it heats up the coolant. A circulation pump routes the heated coolant through the coolant circuit. The blower provides ventilation for the vehicle interior.
The stationary heater is controlled using the stationary heater control unit. The heating mode request is issued however from the climate control system. This evaluates all variables and communicates with the stationary heater control unit.
In its basic setting, the maximum heating/ventilation duration is approx. 50 min. The basic setting can be changed using the diagnosis tester in 5 min increments between 10 and 60 min.
The ventilation/heating mode can be triggered immediately or it can be preprogrammed by entering a departure time. The following control elements are available:
- Stationary heater button
- Multimedia system (for preprogramming only)
- Radio remote control (equipment specific)
- Remote telematics services (equipment specific)
Depending on the vehicle model involved, the stationary heater can also be switched on while driving (heater booster mode).
The function can be ended in the following ways:
- Automatically approx. 5 min after reaching departure time (if engine is not started)
- Automatically, if the difference between the coolant temperature in the engine and the coolant temperature at the stationary heater outlet is less than approx. 5 °C (when engine has been started).
- Automatically if heater overheats
- Automatically if undervoltage occurs
- Automatically upon recognition of crash signal
- Manually using stationary heater button, radio remote control or remote telematics services
The stationary heater control unit continuously sends information on the operating status of the stationary heater to the radio remote control receiver. The information is stored there and it can be retrieved using the radio remote control transmitter. The information is only provided in response to a request from the radio remote control transmitter.
If the SRS system issues a crash signal in an accident to the stationary heater control unit, it switches off the heater. This reduces the risk of fire.
Function requirements
- Stationary heater switched on
- Fuel level above fuel reserve
- No overvoltage or undervoltage
- Interior and outside temperature have been determined.
Check function
Before starting the heating mode, the stationary heater control unit checks the status of all components involved in the heating mode. If a fault is detected, the heating mode is not started. The ventilation mode is activated by the heater irrespective of the test result.
The heater runs a self-test to verify the detected faults. The status is updated by the result of the self-test. Depending on the result, the heater can start the heating mode again the next time an attempt is made to switch it on.
The stationary heater control unit checks the following components when starting and during the heating mode:
- Temperature sensor
- Thermal fuse
- Combustion air blower
- Glow plug/flame monitor unit
- Switchover valve
- Fuel pump (FP)
A defective switchover valve does not result in interruption of the heating mode or its start because this component is not relevant for the safe stationary heater operation.
The air conditioning control panel activates the ventilation or heat function to match the requested and actual interior temperature.
Ventilation function
In the ventilation mode, the climate control system actuates the blower regulator. The blower regulator controls the speed of the blower motor.
Heating function
Depending on the equipment installed, the stationary heater control unit or the air conditioning control panel actuates the circulation pump directly. During heating mode the circulation pump continuously circulates the coolant. The heater heats up the coolant. As from a coolant temperature of approx. 50 °C, the stationary heater control unit switches on the blower motor. The coolant dissipates the heat into the vehicle interior by way of the heat exchanger.
Ventilation/heating mode triggered after entering departure time
The climate control unit sends the entered departure time to the instrument cluster control system. Approx. 60 min before the entered departure time, the instrument cluster requests the required ventilation/heating duration required to reach the set specified temperature on the climate control system. The climate control system than calculates the required ventilation/heating duration based on the outside temperature.
The climate control system sends the calculated ventilation/heating duration to the instrument cluster control system, which then calculates the switch-on time. Once the switch-on time is reached, the instrument cluster control system sends a switch-on request to the climate control system.
| Further basic function | |||
| Antenna system, basic function | GF82.62-P-9901A | ||
| Multimedia system, basic function | GF82.85-P-9900A | ||
| Telematics services, basic function | Vehicles with code 362 (HERMES LTE) | GF82.85-P-9902A | |
| Components | |||
| A/C operating unit, basic function | GF83.40-P-2016A | ||
| Circulation pump, basic function | GF83.40-P-2020A | ||
| Stationary heater unit, basic function | GF83.70-P-2013A |