35
E46 Climate Control
Air Intake
The fresh air/re-circulation flaps are controlled
by a separate stepper motor for the left and
right side.
The stepper motors are controlled by the M-
bus and are located on the left and right sides
of the housing inside the passenger compart-
ment.
The fresh air flaps are closed and the re-circ
doors are opened when the re-circ. button is
pressed with the system switched on.
When the key is turned off with re-circulation on, the fresh air flaps will open. Re-circula-
tion memory in the IHKR control unit is 15 minutes. If the vehicle is started within 15 min-
utes the re-circulation setting will be restored.
If the system is shut off with the blower switch, the re-circulation function will have to be re-
enabled.
Ram effect air compensation
Similar to IHKA, when the fresh air flaps are open their position is affected by vehicle road
speed. This is to prevent an increase in air volume to the cabin with increasing vehicle
speed.
The IHKR receives the vehicle speed input every 2 seconds over the K-bus from the Kombi.
At a speed of 36mph the fresh air flaps will close progressively until the vehicle reaches
96mph, at which time the opening of the flaps will be 20%.
Fresh air flaps
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