The BMW E46 IHKA (integriertes Heizung und Klima automatic), or integrated automatic climate control system, provides the vehicle cabin with heating, air-conditioning and ventilation. The main components and features of this system are as follows:
- Single heater core uses circulating engine coolant to provide cabin heat and window defrosting function
- Blower control via final stage (blower motor resistor pack)
- A/C compressor is electronically controlled
- Air distribution and fresh air volume dependent on vehicle road speed
- Air distribution controlled by self-calibrating stepper motors powered via M-bus
- Automatic maximum for heating and cooling for defrosting functions
- Rear window defogger and heated outside rear view mirrors integrated into the climate control system
- Fresh air microfilter
- Heating and air-conditioning can be personalized via Car Memory / Key Memory function
The fresh air microfilter is used to filter the air coming into the vehicle interior. It also protects the HVAC system components from contamination. A dirty heater core would not provide sufficient heat and a dirty evaporator would not be able to provide sufficient cooling so it's imperative to make sure you always have a fresh microfilter to avoid such issues.
BMW recommends replacing the fresh air cabin microfilter every 10,000 miles or every other oil change. However, depending on the weather and climate the vehicle is exposed to, you may need to change the filter more often. If you start to notice any weird musty smells inside your car, and you're sure your passenger(s) have showered, it may be from a dirty microfilter.
In this article, I will go over the steps involved with changing the cabin microfilter. The process is quite easy and can be done in a matter of a few minutes, saving you time and money by avoiding taking your car to a dealership.
Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.
Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you are working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.
Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.
The fresh air cabin microfilter is located in the engine compartment at wiper cowl (green arrow). You will need to open the hood to access the microfilters plastic housing. The hood release lever is on the driver's side, by the pedals.
To access filter inside the housing, rotate the filter lid locks 90° (green arrows).
Next lift cabin microfilter lid and pull it out of the cowl in an upward direction (green arrows).
Next, remove the microfilter from cowl, it should slide out easily and no tools are needed to remove the actual filter (green arrow).