General

Operation
The climate control system (IHKA) is a water-based automatic heating and air conditioning system. The control system on the water side is based on two electrically operated water valves in separate heat exchangers on the left and right sides. The required temperature in the vehicle is controlled by the mixing flaps. The air is mixed ahead of the heat exchangers without being heated in the flow of ventilation air. Temperature control with the mixing flaps is therefore not possible when the ventilation outlet nozzles are closed manually.

The control unit performs open-loop and closed-loop control functions with the aid of a microcomputer:
- Control of air distribution flaps
- Air flow control
- Interior temperature control
- Cold start interlock
- Windscreen heating control (not installed in 5 Series)
- Rear window defogger control
- Evaporator temperature control
- Auxiliary water pump control
- Defect detection and diagnosis and making available a substitute value for the failed component

A/C Control Panel:

Control Panel

General Block Diagram:

General Block Diagram