Automatic Air-Recirculation Control (IHKA High)

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If the AUC sensor detects an excessively high pollutant level in the environment, the IHKA control unit will automatically switch to air-recirculation mode.

Because of the lack of a fresh-air supply, air-recirculation mode is only available for a limited period of time:

In heating mode at ambient temperatures above 6 °C, air recirculation is limited to 4 minutes. This is followed by fresh air for 1 minute.
In air-conditioning mode at ambient temperatures above 6 °C, air recirculation is limited to 12 minutes.
This is followed by fresh air for 1 minute.
At ambient temperatures between 6 °C and 0 °C, air recirculation is limited to 3 minutes.
At ambient temperatures below 0 °C, air recirculation is limited to 2 minutes.

This is followed by fresh air for 1 minute.

When the engine is started and the AUC function activated, fresh air is always selected for approx. 40 seconds due to the warming phase of the AUC sensor.