GF83.40-P-2181-01Q Control and Operating Unit Comfort Automatic Air Conditioning, Task

GF83.40-P-2181-01Q Control And Operating Unit Comfort Automatic Air Conditioning, Task
- 209.3 up to 31.5.04
- with CODE (581b) Convenience automatic air conditioning

Component Identification:

Task
The comfort AAC control and operating unit (N22/7) controls and regulates all air conditioning functions for the vehicle interior.

^ harmonizing the preselected and actual temperatures and controlling the air outlet temperature at the air vents.
^ Automatic switchover of fresh air to recirculated air mode.
^ Electrical actuation of refrigerant compressor.
^ Actuation of the electric suction fan engine and AC with integrated control

The following additional functions are also regulated by the comfort AAC [KLA] control and operating unit (N22/7) and the required information is forwarded to the processing control units via the Controller Area Network Bus Class B (interior) (CAN-B).

^ Heated rear window
^ Stationary heater (on vehicles with code (228) stationary heater)

The comfort AAC control and operating unit (N22/7) performs the following system actuations:

^ Via the CAN-B: refrigerant compressor; coolant circulation pump; engine and AC electric suction fan with integrated control
^ Via the A/C bus: blower regulator; 10 stepper motors for air distribution

The following sensor signal is transmitted by the comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7) via the CAN-B:

^ Sun sensor values (the overhead operating unit reads in these values for the automatic light control in order to achieve a better redundancy for the system))
^ Dew point temperature (the left door control unit and the right door control unit read in this value to implement a demand- based heated outside mirror)

The following sensor signals are received by the convenience AAC pushbutton control unit (N22/7):

^ Installed sensor: in-car temperature sensor (N22/7b1)
^ direct: evaporator temperature sensor
^ via the CAN B: outside temperature display temperature sensor; refrigerant pressure and temperature sensor
^ via the electronic ignition switch control unit: battery voltage; coolant temperature sensor; engine speed
^ via the instrument cluster: vehicle speed
^ via the A/C bus: C-AAC sun sensor (4 in total); C-AAC [KKLA] multifunction sensor

The comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7) reads in the window and door positions as well as the tilting/sliding roof positions (with code (414a) electric tilting/sliding roof in glass version) to achieve an improved control quality when the roof is open.
The averaged value of the interior temperature with a window open, door open and ground speed = 0 km/h is also recorded for a maximum of 2 min. This ensures that the air conditioning system continues operating immediately with the set interior specified temperature.

The following system settings which were activated before the engine was switched off, are stored by the convenience AAC pushbutton control unit (N22/7) in the EIS control unit.

^ AC OFF mode activated (yes/no)
^ Automatic mode activated (yes/no)
^ Automatic mode with automatic blower control and left/right air distribution activated (yes/no)
^ at manual setting: set blower speed and air distribution
^ Set temperatures specified value

When the engine is restarted, the status stored in the EIS control unit is reactivated.

The convenience automatic air conditioning pushbutton control unit (N22/7) has a diagnostic capability. As a result, any faults which occur are stored in the DTC memory, which can be read out with the help of the STAR DIAGNOSIS system.
When the comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7) is replaced, variant coding must be carried out with the help of STAR DIAGNOSIS.

Temperature buttons warm (1 and 6) and cold (7 and 13)
Pressing the temperature buttons warm (1 or 6) or cold (7 or 13) on the comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7) sets the desired interior temperature separately for left and right.

The comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7) compares the desired temperature to the temperature in the vehicle interior, which is measured by the in-car temperature sensor (N22/7b1) in the comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7).

Using the comparison between actual values and set points, the comfort AAC control and operating unit (N22/7) determines the correct position of the left and right blending air flap actuator motors and actuates these separately for left and right. The selected temperature is reached and maintained as quickly as possible, if warming or cooling of the interior is necessary.

Air distribution switch on left (2) and right (5)
The air distribution can be set manually or automatically:

^ Manual (Automatic button released)
- Turning the air distribution switch on left (2) and right (5)
- Indicated by notch printed in white Automatic
^ (Automatic button engaged)
- Indicated by "AUTO" symbol in the display

Turning the air distribution switch on left (2) and right (5) on the comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7) actuates the various air distribution actuator motors via the A/C bus.

Apart from the 4 basic settings, a further 8 intermediate settings can be selected.

Auto button on left and right
By pressing the Auto buttons on left and right, which are combined with the air distribution switches on left (2) and right (5), the automatic mode for the left and right side can be activated separately. Turning the air distribution switch on left (2) and right (5) then returns the system to manual mode.
In automatic mode, in addition to temperature control the blower output and air distribution are controlled automatically.
The blower speed is continuously controlled depending on the temperature difference between the specified and actual values.

For the electronic control of the air conditioning, in addition to the interior temperature in-car temperature sensor (N22/7b1) in the comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7), the humidity measured via the C-AAC [K-KLA] multifunction sensor is used.

In automatic mode, cooled air may also flow out of the defroster vents. The prerequisites for this are as follows
^ a configured automatic air distribution and
^ dry weather (recognition via the humidity by the C-AAC [K-KLA] multifunction sensor), in order to prevent the windows from fogging up.

Activated charcoal filter button (3)
Pressing the activated charcoal filter button (3) on the comfort AAC control and operating unit (N22/7) switches to operation with the activated charcoal filter; this conducts the fresh air, after flowing through the dust filter, and recirculated air through the activated charcoal filter.
Pressing the activated charcoal filter button (3) actuates the activated charcoal filter flap adjustment motor, which closes the activated charcoal filter flap in the AC housing and thus conducts the air through the activated charcoal filter.
As a result, the pollutant content in the fresh air is reduced and the odor emission decreased. With an increased CO and NOx content in the outside air, recirculated air mode is selected automatically with the aid of the C-AAC [K-KLA] multifunction sensor
Recirculated air mode which is regulated as a function of pollutants is not possible in the AC OFF-mode and with outside temperatures less than 5 °C.

Display (4)
The display (4) is designed to inform the driver of the settings of the ventilation system and air conditioning. The information is provided in form of the words, symbols and digits.
Depending on the setting generated by means of the multifunction steering wheel, the temperature appears in the display (4) either in °C or in °F. Other messages are presented by means of the corresponding symbols.
The display employs a negative technology design, in other words light digits against a dark background.

Recirculated air switch (N22/7s2)
A short press (< 1.5 s) of the recirculated air switch (N22/7s2) actuates the fresh and recirculated air flap actuator motor, which in turn actuates the fresh and recirculated air flap and thus closes the fresh air opening and opens the recirculation duct in order to enable the air to be supplied from the passenger compartment. The LED in the recirculated air switch (N22/7s2) lights up in recirculated air mode.

Recirculation air convenience closing function
If the recirculated air switch (N22/7s2) is pressed for longer than 1.5 seconds, all the open windows and the tilting/sliding roof are closed automatically (windows and tilting/sliding roof must be normalized) in addition to activating the recirculated air function. The LED illuminates during the recirculated air mode. Tilting/sliding roof and power windows are operated one after the other in order to avoid current peaks.

If the button is pressed once again (> 1.5 s), the windows and the tilting/sliding roof are moved back into the previously stored position and the fresh/recirculated air flap moves into the fresh air position (LED off).
The convenience closing function can only be started if the LED in the recirculated air switch (N22/7s2) or the LED in the activated charcoal filter button (3) are not illuminated.
Any window which has been opened manually during this recirculation air phase, remains in this position when the recirculation air function is canceled, all other windows move into the stored position. The positions of the tilting/sliding roof and of the side windows which existed prior to the commencement of the closing operation, are stored by the overhead control panel control unit, the left and right door control unit. The windows and the tilting/sliding roof, which were closed by means of the convenience closing function, remain closed if the recirculated air switch (N22/7s2) is pressed only briefly (< 1.5 s). In this case only the fresh air/recirculated air flap is moved into the fresh air position. The stored positions are canceled when the ignition is switched off.

Defroster button (8)
Pressing the defroster button (8) initiates the defrost function.

The defrost function works according to the following logic:

^ The heating power is controlled by the outside temperature.
^ The entire air flow is directed onto the windshield and front side windows, defroster nozzles open.
^ The air blown in is dehumidified depending on the humidity.
^ The blending air flap actuator motors at left and right regulated.
^ Footwell nozzles closed.
^ Blower capacity 80 %, manually adjustable.

Blower button (10)
The blower button (10) switches the control voltage for the blower regulator in 7 stages (indicated in the display (4) by 7 wedge display segments), depending on the position via the comfort AAC control and operating unit (N22/7). This facilitates control of the blower speed from 0 to 100 %.

AC OFF button (11)
When the AC OFF button (11) on the comfort AAC control and operating unit (N22/7) is pressed, the LED comes on, the refrigerant compressor is shut off and thus the cooling mode is switched off. The air is no longer cooled and dried.
In vehicles with diesel engines the heater booster control unit is also shut off.
All other functions are retained.
The pollutant-controlled recirculated air function is not available in AC OFF mode.
In order to shut off the refrigerant compressor, the comfort AAC (C-AAC [K-KLA]) control and operating unit (N22/7) transmits the shut-off request and the specified value = 0% to the front SAM control unit with fuse and relay module via CAN-B. At the same time, the refrigerant compressor torque is set to "0" and transferred to the engine electronics and the electronic transmission control via the EIS control unit. The front SAM control unit with fuse and relay module sends the canceled load increase signal to the engine electronics via the EIS control unit and switches the refrigerant compressor off after a defined time delay.

Rest button
The residual engine heat utilization system is switched on by pressing the rest button, which is combined with the AC OFF button (11).
When the engine is switched off, the residual heat heats the vehicle depending on the temperature setting on the comfort AAC control and operating unit (N22/7) and the ambient temperature in the vehicle interior.
The vehicle can be heated for approx. 30 minutes, with the engine switched off. The function can only be used when the ignition is switched off or the EIS [EZS] control unit is in position 1. If there is low voltage, the residual engine heat utilization function is automatically switched off.
The flaps for the air distribution and the air volume are regulated automatically.
The residual engine heat utilization function is switched off,
^ if the transmitter key in the EIS [EZS] control unit is moved to position 2,
^ after approx. 30 minutes or
^ if the battery voltage drops below 11 V.