Hi and thanks for using 2CarPros.Com.
This could be the result of a few things. However, I did find a technical service bulletin (TSB) related to your concerns. Here is the TSB:
A/C - IHKA is Inoperative and Fuse 48 is Blown
Vehicle Technical Service Bulletins By Symptom A/C - IHKA is Inoperative and Fuse 48 is Blown
A/C - IHKA IS INOPERATIVE AND FUSE 48 IS BLOWN
SI B 64 08 06
Heating and Air Conditioning System
This Service Information bulletin replaces S.M. B64 201 03 dated July 2003.
IHKA Inoperative Fuse 48 Blown
The IHKA (Automatic Heating Air Conditioning System) functions intermittently and the control panel display blanks out. The temperature settings may also change automatically. Eventually the IHKA cannot be operated anymore.
1. Pinched or chafed M-Bus wiring harness
2. Fuse 48 blown, caused by short in wiring harness
Check the following areas for problems:
1. Inspect for a pinched wiring harness, especially in the driver's side knee pad area between the instrument panel carrier and the IHKA housing.
2. Inspect the wiring harness for any chafing damage, especially from the sharp edges of the instrument panel in the glove box area.
3. Check for wiring shorts in the area of the water valve assembly.
4. Inspect the wiring at the auxiliary water pump, especially in the area of the frame rails.
5. If fuse 48 keeps blowing, check the wiring between fuse 48 and the IHKA control panel for shorts.
6. If any damage is found in the wiring, repair the wiring and reposition the harness away from the affected area. Edge protectors can be installed to ensure the wiring is not damaged in the future. The edge protector can be ordered in a unit of 1 meter and can be cut into the appropriate length.
7. If wiring has no shorts and Fuse 48 is not blown, check power supply and ground at the IHKA control module. Ensure pins are not loose at IHKA module connection.
Okay, with that being said, I need you to check fuse 48. It is located behind the glove box in the fuse panel. See the attached picture for location. If the fuse is blown, you can try to replace it with an equal type fuse. If it works and then blows again, you need to check the wiring as described above.
Here is a link which describes checking wiring:
I hope you find this helpful. Let me know what you find or if you have other questions.
Tuesday, July 31st, 2018 AT 7:51 PM