Heater Circuit Function

GF83.20-P-2003P Heater Circuit Function

MODEL 203.0 /2 /7 up to Model Year 8







Shown on engine 611
1 Cap
2 Expansion reservoir
3 Radiator
4 Coolant thermostat
5 Coolant pump
6 Oil filter with heat exchanger
8 Heating system heat exchanger
101/6 Exhaust gas recirculation cooler
G2 Alternator
M13 Heating water circulation pump
N33/2 Heater booster control unit
A Coolant return flow
B Coolant feed
C Vent line
M Engine
S Windshield washer fluid reservoir

The coolant pump (5) pumps cold coolant through the engine (M). There, the coolant absorbs engine heat. Shortly afterwards the heated coolant is routed through the heat exchanger (8), where the heat is dissipated to the passenger compartment air.

The heater heat exchanger (8) is continuously supplied with coolant, the Duo valves used previously for regulating the flow rate are no longer applicable.

Control is carried out as a function of the temperature desired in the vehicle interior via the blend air flaps which are actuated separately for the left and right sides via the left blend air flap actuator motor and right blend air flap actuator motor.
The coolant reaches the coolant pump (5) again via the coolant return (A) in which the coolant circulation pump (M13) is located. By far the larger part of the coolant does not flow through the heater, but from the engine (M) to the coolant thermostat (4). Depending on the water temperature, it routes the coolant through the radiator (3) or directly to the coolant pump (5).