GF83.20-D-2010H Rear Air Conditioning System Heating Circuit, Function
GF83.20-D-2010H Rear Air Conditioning System Heating Circuit, Function
- with CODE (H13) Additional heat exchanger in load compartment
16 Front heater heat exchanger
21 Radiator expansion tank
22 Water pump
23 Thermostat
24 Radiator
36 Rear heating system heat exchanger
A Heater water return
B Heater water supply
C Vent line
D Coolant feed
E Coolant return
M Engine
A32/1y1 Rear heater water valve
M13/4 Circulation pump
The heating circuit is connected to the engine's cooling circuit.
The following components are connected to the cooling circuit:
- Radiator expansion tank
- Water pump
- Thermostat
- Radiator
- Engine
The front heater heat exchanger, the rear heater heat exchanger, the circulation pump and the rear heater water valve are connected to the heating circuit.
The rear heater heat exchanger is connected in parallel to the front heater heat exchanger in the heating circuit. Coolant always flows through the front heater heat exchanger, the flow of coolant through the rear heater heat exchanger depends on the position of the flap integrated in the rear heater water valve.
The cooling circuit is divided into the following sections:
- Coolant feed
- Coolant return
- Heater water supply
- Heater water return
- Vent line
During the warm-up phase and normal engine operation, coolant is delivered to the engine coolant pipes by the water pump via the coolant feed line. The coolant is heated up in the engine coolant pipes.
The thermostat remains closed until the coolant has reached a certain temperature. With the thermostat closed, a small quantity of coolant reaches the front heater heat exchanger and the rear heater heat exchanger by means of the circulation pump integrated in the heating water feed. This amount of coolant is additionally controlled by the rear heater water valve according to actuation by the AAC [KLA] control and operating unit (S98).
The coolant flows back to the coolant feed from the front heater heat exchanger and the rear heater heat exchanger via the heating water return. The rest of the coolant flows from the closed thermostat over the coolant return line to the radiator and from there over the water pump back to the coolant feed line.
Once the coolant has reached a certain temperature, the thermostat opens and a fixed quantity of coolant is delivered to the front heater heat exchanger and the rear heater heat exchanger by means of the circulation pump integrated in the heating water feed. This amount of coolant is additionally controlled by the rear heater water valve according to actuation by the AAC [KLA] control and operating unit. The coolant is delivered back to the coolant feed from the front heater heat exchanger and the rear heater heat exchanger via the heating water return.
A fixed quantity of coolant is also delivered to the radiator via the coolant return line, from where it is returned to the coolant feed line via the water pump.
The radiator expansion tank compensates for any possible coolant loss in the coolant circuit via the coolant feed line and keeps the heated coolant at a constant pressure.
Excess coolant flows from the radiator over the vent line back into the radiator expansion tank.
