Flap motor

The flap motors are activated by the control unit of the heating and air conditioning system (IHKR and IHKA) via the LIN bus and are supplied with power and an earth connection. In the idle state, the control unit of the heater and air conditioning system switches the supply voltage off.

The flap motors communicate across the LIN bus with the heating and air conditioning system control unit. The flap motors are switched in series on the LIN bus.

The flap motors in the heater/air conditioning system are all the same. Differences in operation are due only to the respective programmed address. Each flap motor is assigned a certain address. The address determines which function the flap motor assumes in the system network. For example, the footwell flap motor knows that messages are being addressed to it via this address (e.g. open flap). Via this address, the control unit of the heater and air conditioning system also knows, for example, from which flap motor it has received a fault message.

Prerequisite for successfully addressing the flap motors is a correct encoding of the control unit of the heating and air conditioning system (IHKR and IHKA).

After starting auto-addressing, the last flap motor in the series connection topology is programmed with its address. Then the penultimate flap motor in the topology is programmed with its address and so on until all the addresses have been assigned. Therefore the installation position of the flap motor in the wiring harness decides which address is programmed to the flap motor.

If, for example, the last flap motor in the topology is not connected to the IHKA control unit wiring harness during the auto-addressing process, or there is no connection through the local interconnect network bus: The penultimate flap motor in the topology is wrongly identified as the last flap motor in the topology. As a result this flap motor is assigned the wrong address. The remaining stepper motors also receive the wrong address. The wrong addresses are also assigned if the connectors are mixed up.

If several flap motors are entered in the fault memory with the fault "not responding", then there is probably an open circuit in the connection through the local interconnect network bus. The open circuit (wiring, connector, flap motor) should be looked for in the flap motor that comes first in the topology out of all the flap motors entered.

The following flap motors are installed in the heating and air conditioning system:

• Fresh air/recirculated air flap motor
• Footwell flap motor
• Defroster flap motor
• Mixing flap drive

The flap motors are connected to the control unit of the heating and air conditioning system by 4-pin plug connections.