GF83.70-P-3066T Activate Heater With Stationary Heater Switch, Function

GF83.70-P-3066T Activate Heater With Stationary Heater Switch, Function
- with CODE (228) Stationary heater

Component Identification:

Function requirements
^ Circuit 30
^ Sufficient remaining quantity of fuel in tank

Function
The STH switch signal is forwarded by the lower control panel control unit via CAN-B to the STH control unit.
This then initiates the "Ventilate or heat" query via CAN-B to the AAC [KLA] control unit. The AAC [KLA] control unit determines the current interior and outside temperature.
Depending on the values determined and the last setting of the AAC [KLA] control unit, the AAC [KLA] control unit makes a decision either for heating or ventilation and then transmits the decision to the STH control unit.

If the decision is for heating, a query on the status of all components involved in the heater operation is conducted and a self-test is performed if required. The heater operation is not started in the event of a relevant fault. However, the stationary ventilation function is always performed, irrespective of the result.

Heating decision
The fuel metering pump is actuated to supply fuel and the heater unit starts heater operation.
To enable the interior to be heated up faster, the heater unit regulates the flow of coolant, depending on the temperature, between the small and large coolant circuit via the switchover valve. The coolant circulation pump ensures that the temperature- controlled coolant is circulated in the coolant circuit.
When the temperature is at a sufficient level, the AAC [KLA] control unit actuates the blower motor via the blower regulator.

Ventilation decision
During stationary ventilation only the blower is actuated in the vehicle.
The AAC [KLA] control unit actuates the blower motor via the blower regulator.

Depending on the interior temperature, a switchover from stationary heating to stationary ventilation and vice versa can be made.

Status indicator
The red indicator lamp in the STH switch indicates stationary heating, and the blue lamp indicates stationary ventilation.