Heating Circuit

Component Identification:

On Vehicles With Rear Air Conditioning:

Function
The coolant pump (5) pumps cold coolant through the engine. There the coolant absorbs engine heat and is heated up. The heated coolant is led through the heat exchanger (8) where the heat is released into the interior air. The quantity of coolant flowing through the heater heat exchanger (8) is controlled by the duovalves (A31y1, A31y2) in the coolant return (A). The quantity of coolant can be controlled separately for the left and right side.
The coolant flows back to the coolant pump (5) Via the coolant return (A). A far higher proportion of the coolant does not flow through the heater but from the engine to the coolant thermostat (4). Depending on the water temperature it routes the water through the radiator (3) or straight on to the coolant pump (5).

Vehicles with rear air conditioning (code 582)
On Vehicles with rear air conditioning (code 582) heated up coolant is also supplied to the heater heat exchanger (9) in the rear. The quantity of coolant flowing through the heater heat exchanger (8) in the rear is controlled by the duovalves (A31y1, A31y2) in the coolant return (A). The quantity of coolant can be controlled separately for the left and right side.