A/C - Front and Rear Center Vent Temp. Difference
SI B64 02 11Heating and Air Conditioning
February 2011
Technical Service
SUBJECT
Air Temperature Difference Between the Front and Rear Center Air Vents
MODEL
F07 (5 Series Gran Turismo)
F10 (5 Series)
Vehicles produced from 8/02/09 to 9/06/10 without option 4NB (4-zone climate control)
SITUATION
During the heating operation, cold air comes out from the rear center vents, even though the front stratification thumbwheel is set to warm. The air temperature at the rear center vents is approximately 8 to 10 degrees C lower than the air temperature at the front center vents.
CAUSE
The rear center vents do not have a stratification thumbwheel or a temperature sensor.
INFORMATION
The rear passenger compartment air temperature is regulated by blending the rear footwell and center vent air according to the characteristic curve (y factor) as a function of the IHKA temperature setting and the outside temperature.
PROCEDURE
Do not replace any parts.
If the situation above can be verified, program and code the vehicle using ISTA/P 2.40.0 or higher.
Note:
Programming the IHKA will only improve the temperature control characteristic curve slightly. This means that the temperature of the air from the rear center vents will be slightly warmer than before, but it will not be the same temperature as the air coming from the front center vents.
Note that ISTA/P will automatically reprogram and code all programmable control modules that do not have the latest software.
For information on programming and coding with ISTA/P, refer to CenterNet / Aftersales Portal / Service / Workshop Technology / Vehicle Programming.
WARRANTY INFORMATION