Temperature Control

WARNING: This page does not describe the selected car, but rather 33 other vehicles, including the 2010 BMW M5, 2009 BMW M5, 2008 BMW M5, 2008 BMW 760Li, and 2007 BMW M5. However, it is still accessible from the selected car via links, so may be relevant.

In the heating/air-conditioning system, the air-mass flow is first cooled and dried at the evaporator (provided the air conditioner is switched on). Then the airflow is heated to the required temperature at the heating system heat exchanger.

IHKA Basic
The temperature in the heating system heat exchanger is controlled with the help of the heating system heat exchanger sensor and a pulsed water valve in the heater circuit. The water valve is actuated with a pulse-modulated signal (PWM signal) by the IHKA control unit. A map for the heating system heat exchanger determines the opening times for the water valve, depending on the engine speed.

A master controller regulates the temperature inside the vehicle. Regulation is based on the specification set at the rotary switch (adjustment range: 17-27 °C) and the actual value (= interior temperature). The lead parameter is derived from the comparison of the actual interior temperature and the corrected specification (customer setting + ambient temperature).

Compared to the set specification, the interior temperature is raised in the cold so that a comfortable level is achieved even at negative temperatures, despite the temperature setting being unchanged. The ambient temperature is transmitted through the body CAN (controller area network) to the IHKA control unit.

An auxiliary regulating circuit relieves the master controller by eliminating any fault quantities that could be detected in the heating/air-conditioning system in the form of a temperature change. Disturbances are caused by:
- Fluctuations in air volume
- Fluctuations in coolant flow in engine heater circuit
- Temperature changes in fresh air
IHKA High
The separate temperature setting for the driver's side and the front-passenger side affects:
- Heating system heat exchanger with left/right separation
- 2 heating system heat exchanger sensors
- Dual water valve
The temperature is regulated by 2 master controllers. Regulation is based on the specification set at the rotary switch and the actual value (= interior temperature). Through the left/right separation, 2 auxiliary regulating circuits relieve the two master controllers.

The solar sensor compensates for additional fault quantities caused by external sources of light or heat (e.g. direct sunlight).

NOTE: Reaching maximum outlet temperature in ventilation area. The maximum outlet temperature in the ventilation area is reached as follows:

Set the rotary switch for temperature selection to maximum temperature (28 °C)
Set temperature layering as follows with the CID:
- IHKA Basic:
  Air stratification to "red" (warmer)
- IHKA High:
  All 4 red bars must be displayed.