3 Series E90 335xi (N54) SAL
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.
Regulation is based on the nominal value set by the vehicle occupants at the temperature selector
wheel and the calculated actual value.
(nominal values are set via a temperature selector wheel on the IHKA control panel.
The actual value is calculated from the temperatures measured by the interior temperature sensor and
the heating system heat exchanger sensor).
The lead parameter is calculated from the comparison between the actual value for the interior
temperature and the corrected nominal value (calculated from temperature request and 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 to the IHKA control unit via the body CAN (body Controller
Area Network).
-
IHKA High
The separate temperature setting for the drivers side and the front-passenger side affects:
- Heating system heat exchanger with left/right separation
- 2 heating system heat exchanger sensors
- 2 ventilation temperature sensors
- Dual water valve
Evaporator control (IHKR, IHKA only)
The evaporator temperature is regulated by means of the evaporator temperature sensor and the expansion
valve. The evaporator temperature is set to the predefined specification of 2
°
C. Lower temperatures are not
possible due to the risk of icing.
If the "variable evaporator control" function has been encoded, the nominal evaporator temperature is calculated
between 2 and 7
°
C. The specification depends on the ambient temperature, the ventilation temperature and
the refrigerant pressure. A variable evaporator control reduces dehumidification. This reduces the risk of
mucous membranes drying out.
Air distribution setting
For the best possible operation of the air distribution, it is important for the manually adjustable air vents to be
open.
•
IHR, IHKR
Air distribution selection is only possible manually with the air-distribution control wheel.
•
IHKA
Occupants have the possibility of allowing the air distribution to be decided by the automatic program
(AUTO button).
Alternatively, individual, personal settings are possible through manual selection (defrost, ventilation,
footwell).
If the relevant equipment is fitted to the vehicle, it is also possible to make a fine adjustment via the CID
(Central Information Display) in the submenu Air distribution.
Compared to manual selection, fine adjustment offers the additional possibility of further individualisation of
the air distribution.
> E70: IHKA Basic
SBT Integrated heating control and air-conditioning system E70, E81, E82, E87, E90,
BMW AG - TIS
23.02.2013 16:41
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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