Behavior 3: Faulty circulating pump

Auxiliary heater temperature increases. Heat exchanger temperature does not increase. Engine coolant temperature remains constant.

Fig 1: Heater System Coolant Flow Diagram (Coolant Temperature Constant)

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Heater System Coolant Flow Diagram (Engine Coolant Temperature Increase)

Courtesy of BMW OF NORTH AMERICA, INC.

No	Designation
1	Coolant flow rate
2	Heat exchanger sensor
3	Heat exchanger for heating system
4	Water valve
5	Auxiliary heater temperature
6	Auxiliary heating
7	Recirculation pump
8	Changeover valve
9	Engine coolant temperature