GF83.60-D-0001H Rear Heater, Function

GF83.60-D-0001H Rear Heater, Function

- with CODE (H13) Additional heat exchanger in load compartment

The rear heater can only be controlled or regulated using the rear blower switch (S98s16) integrated into the KLA control and operating unit (S98), except code (HH9) Regulated air conditioning (Tempmatic) or with code (HH9) Regulated air conditioning (Tempmatic), using the rear blower control button (+) (S98s2) and the rear blower control button (-) (S98s3) which are integrated into the KLA control and operating unit, or using the rear temperature selection switch (S98s15) integrated into the KLA control and operating unit, if it is switched on using the rear air conditioning button (S98s7) integrated into the KLA control and operating unit.
Activation of the rear heater is indicated by illumination of the red light emitting diode (LED) in the rear air conditioning button.
The rear heater enables a pleasant interior climate to be set in the passenger or load compartment of the vehicle during different weather conditions.

Actuation and subsequent regulation of the ventilation is conducted electrically using the rear heater blower regulator (A32/1a1) which regulates the rear heater blower motor (A32/1m1).
Temperature is regulated electrically via the rear heater water valve (A32/1y1) which adjusts the heating water feed line flap via the rear heater water valve motor (A32/1m2).
The subfunctions of the rear heater are summarized as follows:
- Rear heater ventilation
- Rear heater heating circuit
- Rear heater temperature control

Rear heater ventilation
The ventilation system ensures circulation of the recirculated air in the passenger or load compartment of the vehicle.

Ventilation is only provided in air recirculation mode, no fresh air is drawn in.

For vehicles except code (HH9) Regulated air conditioning (Tempmatic), the rate of circulation for the recirculated air is regulated using the rear blower switch.
For vehicles with code (HH9) Regulated air conditioning (Tempmatic), the rate of circulation for the recirculated air is regulated using the rear blower control button (+) and the rear blower control button (-).
The recirculated air is only distributed in the footwell area via the blow out air duct and the air vent in the side paneling at the bottom left front behind the driver seat.

Rear heater heating circuit
The cooling water is heated in the cooling water circuit by the engine. The heated coolant is then led via the heater water feed line through the front heater heat exchanger and the rear heater heat exchanger, which dissipate the heat to the aspirated recirculated air.
The coolant is then returned into the cooling water circuit via the heating water return.
The coolant pump as well as the circulation pump (M13/4) integrated into the heating water feed line ensure circulation of the coolant in the coolant circuit. The front heater heat exchanger always has coolant flowing through it, whereas the flow of coolant through the rear heater heat exchanger is dependent on the position of the flap integrated into the rear heater water valve.

Rear heater temperature control
The rear temperature selection switch is used to set the temperature required in the passenger or load compartment of the vehicle.
Depending on the temperature required, the position of the flap integrated into the rear heater water valve is adjusted electrically via the rear heater water valve motor. This in turn regulates the flow of coolant through the rear heater heat exchanger.