Air Intake

IHKA E32 AIR INTAKE







The air intake flaps (2 fresh and 2 recirculating) are operated as pairs by stepper motors (fresh and recirculating) the same way as on the IHKR systems.

IHKA air intake flap operating logic is:
- With the engine running and the IHKA system turned "off" (blower thumbwheel in "0"), the control module closes the fresh air flaps and the recirculating air flaps.
- Rotating the thumbwheel out of position "0" turns on the IHKA system and the fresh air flaps open fully (100% open).
- With the IHKA system operating, pressing the recirculating air button causes the fresh air flaps to close and the recirculating air flaps to open.
- If, during normal system operation (A/C compressor button pressed, recirculating air button not pressed), the left Y-factor drops to -20% (heavy cooling demand), the control module automatically closes the fresh air flaps to about 1/3 open and fully opens the recirculating air flaps.
- This "auto-recirc" mode is maintained until the left Y-factor rises to 5% (moderate cooling demand), at which time the recirculating air flaps fully close and the fresh air flaps fully open again.


NOTE: The "auto-recirc" mode is possible only with the A/C compressor button pressed. If the A/C compressor button is not pressed, the fresh air flaps will remain fully open and the recirculating air flaps will remain fully closed, regardless of Y-factor.


- At vehicle speeds above 37 mph the control module partially closes the fresh air flaps to compensate for the ram-air effect as shown below:







NOTE: Beginning with control module software version "02" (9/87), the vehicle speed input does not affect the fresh air flap position.


- At engine shutdown (with the IHKA system operating), the control module moves the fresh air flaps to the fully open position.