Table of Contents Rear Air Conditioning Subject Page Purpose of the System .3 System Components.4 Evaporator Housing with Aotuators and Fiaps .4 Stepper motor oontroi .4 Aotuation reiiabiiity .5 Caiibration run .6 Position run .6 Refrigerant Circuit.7 Refrigerant Capaoity.9 Refrigerator Box.9 Biower and Biower Controi Moduie .10 Reoirouiating Air Fiiter.11 Evaporator Temperature Sensor.11 Controi Panei with Eieotronios .11 Wiring Harness with Conneotors .12 Caiibration of ieft/right oontroi paneis .13 Rear Air Conditioning Duot Work .14 System Operation .15 Controi Unit Operating Matrix.18 Operation via iHKA.18 Operation via oontroiier (i-Drive) .18 Service Information.21 Fiiiing mode .21 Diagnosis .21 Diagnosis with Tester .23 Controi unit identifioation data.23 Vehioie identifioation number.24 Fauit node memory.24 Controi unit status data, defauits .24 Condensation Water Drain .24 Review Questions .25 Initial Print Date: 1/03 Revision Date: Rear Air Conditioning Model: E66 Production: Start of Production MY 2003 Objectives: After completion of this module you should be able to: • Identify the oomponents and looations of the Rear Air Conditioning System • Explain the operation of the FKA • Diagnosis error oonditions in the FKA 2 Purpose of the System From E66 series launch, a Rear Compartment Air Conditioning system (FKA) may be installed as an option. The rear compartment air conditioner is located in the front area of the luggage compartment and consequently reduces the volume of the luggage compart¬ ment by about 20 percent (incl. trim panels). The control and integration of the rear compartment air conditioning system in the IHKA refrigerant circuit is designed so that independent operation is possible for either the front or rear unit. The air required for rear compartment air conditioning is drawn in via a particle filter (recir¬ culated air filter) from the luggage compartment. The rear compartment air conditioning system additionally supplies cold air to an integrat¬ ed refrigerator box. This refrigerator box should not be confused with the electrically oper¬ ated refrigerator box that is optionally available also for the E65. The rear air conditioning system performs the following functions: • Regulates air volume distributed through rear ducts. • Temperature and air volume control for left and right rear occupants. • Air conditioning (cooling). • Electronic control of rear evaporator temperature. • Operation of integrated rear compartment refrigerator box. 3 Rear Air Conditioning System Components The rear air conditioning system consists of the following oomponents: • Evaporator Housing with Aotuators and Flaps • Refrigerant Circuit Evaporator and Expansion Valve Refrigerant Cut-Off Valve Conneotion point for refrigerant lines • Refrigerator Box • Blower and Blower Control Module • Reoiroulating Air Filter • Evaporator Temperature Sensor • Control Panel with Eleotronios • Rear Air Conditioning Duot Work • Wiring Harness with Conneotor Evaporator Housing with Actuators and Flaps. Connection Point for Refrigerant Lines. Refrigerator Box Blower, Blower output Final Stage and Recirculating Air Filter. Evaporator Housing with Actuators and Flaps The air is distributed and mixed by means of 4 flaps and stepper motors in the rear air oonditioning unit. Stepper motor control The 2 stratification and ventilation flaps in each system are adjusted by means of 4 bipolar stepper motors. The stepper motors are connected by means of a step-down gear mech¬ anism in order to ensure the required flap torque. The connection is made up of a three- wire ribbon cable connection to which all stepper motors are connected in parallel. 4 Rear Air Conditioning View from front View from trunk Stepper Motors for Air and Stratification Fiaps 1. Drive for air flap, R/S air volume. 2. Drive for air flap, L7S air volume. 3. Drive for R/S stratification flap. 4. Drive for IVS stratification flap. The three bus lines carry the supply voltage, ground and serial data information. An address is assigned for eaoh of the individual stepper motors for individualization purpos¬ es. Eaoh programmed address oan be written only one single time and oan then no longer be deleted or ohanged. Eaoh stepper motor is a oontrolled unit. It monitors all data on the bus, however, it aooepts and answers only if its own address is reoognized and no fault has ooourred in the trans¬ mission of the message Only the stepper motor with the written address matohing the "monitored" address aooepts, after oheoking, the oontent of the message, exeoutes the reoeived oommand and generates a status message as a response that is sent baok to the oontrol unit. Actuation reliability Different torques result for the 4 stepper motors as the result of ohanges in the system volt¬ age. While the motor is aotivated with low-noise sine mode at voltages V (B-rTERM30) > 11 V, the drive mode ohanges over to full step mode at lower voltages. Changeover of drive mode: V (B+TERM30) < 9.0 V V (B+TERM30) >9.0 V and < 10.0 V V (B+TERM30) > 10.0 V and < 11.0 V V (B+TERM30) >11.0 V and < 16.0 V V(B+TERM30) > 16.0 V Motor stops Motor runs at 140 Hz and in full step mode Motor runs at rated frequenoy and in full step mode Motor runs at rated frequenoy and in sine mode Motor stops (due to power loss in the drive 1C) These oonditions also apply to the oalibration run! 5 Rear Air Conditioning Calibration run None of the stepper motors features an aotual position detention funotion, i.e. they always move relative to a referenoe point. One of the flap end positions (0 or 100% serves as the referenoe point). The flaps assume an end position after replaoing the oontrol unit or in the event of inter¬ ruptions in the voltage supply during normal operation. The end position is seleoted suoh that the subsequent set position oan be reaohed over the shortest distanoe (position opti¬ mization). If oalibration of the stepper motors is neoessary due to voltage failure, the bit gen¬ erated for this purpose is prooessed by the oontrol unit itself. Optimization of the motor running times is aohieved by inoorporating the set positions: If the flap is open following oalibration, the oalibration run is also oonduoted in "open" direotion. Position optimization therefore takes plaoe based on the following oriteria: Position optimization during oalibration: Setpoint > 50%: oalibration in OPEN direotion Setpoint < 50%: oalibration in CLOSED direotion Position run The flaps assume oertain positions after turning off the engine (terminal 15 de-energized). The ventilation flaps are olosed and the stratifioation flaps are moved to the mid-position. Adjustment angle, number of steps and adjustment time Ventilation flap left/right Adjustment angle: 100 degrees Number of steps: per 15 degrees = 300 steps (at 100 degrees = 2000 steps) Adjustment time: CLOSED <-> OPEN approx. 10 seoonds Stratification flap left/right Adjustment angle: 109 degrees Number of steps: per 15 degrees = 300 steps (at 109 degrees = 2180 steps) Adjustment time: CLOSED <-> OPEN approx. 11 seoonds Note: The calibration run can also be triggered by the diagnosis tester. Flaps/flap kinematics Flap positions The programs for positioning the flaps are only aotive when Terminal 15 is aotive. Rear compartment refrigerator box operation (rear compartment air conditioning left/right OFF) • Ventilation flaps: 0% • Stratification flaps: 50% 6 Rear Air Conditioning MAX-AC • Ventilation flaps: 100% • Stratification flaps: cold Manual settings The setting of the ventilation flap is dependent on the blower status on the left and right side. The flap is opened to 100% on the side with the largest blower share. Restriction of the ventilation flap on the side with the smaller blower share is determined in accordance with the following characteristic curve: This theoretically determined flap opening function still needs to be corrected by the device¬ dependent flap characteristic curve illustrated in the following. Consequently, the actual flap opening is determined individually for each side, corresponding to the required volume of air. The flap correction characteristic curve is the same for both sides. Refrigerant Circuit 8 IHKA Refrigerant Circuit 1. Auxiliary Fan 2. Condenser (2A) with Dryer (2B) 3. Refrigerant Compressor 4. Pressure Sensor 5. Fill adapter port 6. Bulkhead Interface 7. IHKA Evaporator 8. Front Shut Off Valve 9. IHKA Expansion Valve 10. Refrigerant Lines to FKA The rear compartment air conditioning system (FKA) is connected to the refrigerant circuit of the IHKA. The two circuits are isolated by means of two shut-off valves that are fitted only in connection with the rear compartment air conditioning system. The shut-off valves are fit¬ ted in the pressure line ahead of the respective expansion valves of IHKA and FKA. Two shutoff valves provide the separation between the two refrigerant circuits. The front shut-off valve blocks off the refrigerant circuit with respect to the front evaporator (IHKA). The rear shut-off valve blocks off the refrigerant circuit with respect to the rear evap¬ orator (FKA). 7 Rear Air Conditioning When both systems are in operation, the output of both systems oan be oontrolled inde¬ pendently by means of oorresponding oyolio timing of the valves. At least one valve, how¬ ever, must always be opened. The oompressor output depends on the system with the higher refrigerant requirement. The system with the lower refrigerant requirement is switohed oyolioally. Both systems are switohed oyolioally by the shut-off valves in partial load mode. The oompressor runs oon- tinuously at low output. Both valves are opened and the oompressor runs at maximum output at full load. Both shut-off valves (front in the IHKA and rear in the FKA) are aotivated by the FKA and are olosed when no power is applied. If a rear oompartment air oonditioning system is installed, the IFIKA must be ooded to "FKA installed." Otherwise, the shut-off valves will remain olosed and non-operative. Damage may even be inourred! Rear Evaporator and Expansion Valve 1. Evaporator 2. Expansion Valve 3. Connection for Refrigerant Lines 4. Rear Shut Off Valve 4 Rear Refrigerator Refrigerant Pressure Line to FKA Refrigerant Suction Line from FKA FKA Line connections 8 Rear Air Conditioning Refrigerant Capacity Vehicles equipped with FKA have an increase in the refrigerant capacity of 310 grams and increase in the refrigerant oil oapaoity of 60 grams. Refrigerator Box The rear oompartment refrigerator box is looated behind the oenter armrest of the rest seats. From here, the rear oompartment refrigerator box oan be oonveniently opened and switohed on. Cooled air from the rear oompartment air oonditioning system flows through the rear oom¬ partment refrigerator box. The air is then direoted into the luggage oompartment. Cooled air from the rear oompartment air oonditioning system flows through the rear oom¬ partment refrigerator box while the engine is running. 1. Grip to open refrigerator box. 2. push button switch w/Blue LED. 3. Cooling air inlet. 4. Air outlet into luggage compartment. To maintain operation of the rear oompartment refrigerator box when the rear oompartment air oonditioning system is switohed off (left and right OFF), only the ventilation flaps are olosed and the entire oooling air is made available for the rear oompartment refrigerator box. In this oase, the blower operates at a fixed setting (EEPROM value). The rear oompartment refrigerator box oan be switohed on or off both by means of a push¬ button on the oover of the refrigerator box. Funotion feedbaok takes plaoe by means of a blue LED in the push-button. Operation of the rear oompartment refrigerator box via the push-button is only possible, however, when both the left and the right oontrol panel of the rear oompartment air oonditioning system are in OFF mode. The FKA is then operated at minimum blower stage and minimum temperature. The rear oompartment refrigerator box is always switohed on automatioally as soon as one of the two oontrol panels assumes manual mode or when MAX AC is aotive. In this ease, the push button has no funotion. 9 Rear Air Conditioning Blower and Blower Control Module 1. Blower final stage 2. Blower 3. Recirculating Air Filter 4. Condensation water drain Blower and Blower Control Module Blower and Blower Control Module shown removed from Rear Air Conditioning unit. Blower Volume control Due to the separate control for the right and left, the blower output is oorreoted as a funo- tion of the following faotors: • Respeotive blower setting • Maximum value of both blower settings • Correotion faotor In manual setting mode, the blower oan be set direotly by the blower adjuster between min¬ imum and 75% of the maximum value. Aotivation to 100% is only possible via the MAX AC funotion. The potentiometer value of 0 - 100% is oonverted to the blower proportions on the basis of a oharaoteristio ourve (EEPROM values). 10 Rear Air Conditioning Recirculating Air Filter The demands made of the recirculating air filter correspond to the general quality specifi¬ cations for particle filters (BMW QV 64 028). The service intervals that are defined in the maintenance manual also depend on these requirements. Evaporator Temperature Sensor The resistance of the Evaporator Temperature Sensor should be approx. 9k Ohms. The working range is -10 °C...-r40 °C and the substitute value is -10 °C. Control Panel with Electronics Left side Control Panel Right side Control Panel 1. Stratification Knob 2. Max AC cooling button 3. AC Blower control Knob 4. IVS OFF Button 5. Lever for air flow directional control Control panels are provided on the left and right for individual control of the rear compart¬ ment air conditioning system. These control panels are also referred to as satellites. While the left-hand control panel only contains control and indicator elements, the right- hand control panels also contains the control electronics. The push-buttons feature LEDs to indicate when the corresponding function is active. The following colors in the push-buttons indicate the active function: • MAX AC Green • OFF Orange • Rear compartment refrigerator box ON Green All buttons are equipped with a second LED to serve as a symbol and locator light. All function LEDs are activated by the FKA control unit to ensure that the LEDs serve as a reliable feedback for the program status. 11 Rear Air Conditioning The function LEDs are powered via a voltage regulator to ensure their brightness does not vary in the event of voltage fluotuations. Sinoe the push-buttons are not looked meohanioally, their priority is defined by way of pro¬ gramming. The funotion lighting of the lower-ranking push-button is switohed off for the purpose of indioating the priority to the oustomer. The status of the rear oompartment air oonditioning system is additionally shown on the oontrol display. Right Side Control Unit With Control Electronics Wiring Harness with Connectors 1 2 L/S Control Panel 1. 12 Pin Socket 2. Air Duct Connection Pin Description L7S 12 Pin Socket 1. B+ Supply Left 7. Not used 2. Temperature pot,I/s 8. Push-buttons, I/s 3. Blower pot, I/s 9. MAX AC LED, I/s 4. Locator light, PWM 10. OFF LED, I/s 5. VCC Monitor, I/s 11. Not used 6. Ground FKA, I/s 12. Monitor lighting. I/s 1 R/S Control Panel 1. Air Duct Connection 2. 18 Pin Socket 3. 12 Pin Socket Pin Description R/S 12 Pin Socket 1. B+Supply Right 7. Not used 2. Temperature pot,r/s 8. Push-buttons, r/s 3. Blower pot, r/s 9. MAX AC LED, r/s 4. Locator light, PWM 10. OFF LED, r/s 5. VCC Monitor, r/s 11. Not used 6. Ground FKA, r/s 12. Monitor lighting, r/s 12 Rear Air Conditioning Pin Designation 18 Pin Socket R/S Control Unit 1. Terminal 30 10. CAN Bus High 2. MBus(MUX4) 11. CAN Bus Low 3. Terminal 31 12. Sensor Ground 4. Refrigerant shut-off valve, Front 13. Ground Stepper Motors 5. Refrigerant shut-off valve, Rear 14. Supply Voltage, Stepper Motors 6. Temperature Evaporator, Rear 15. Ground Stepper Motors 7. Not used exoept on Protection Vehicles 16. Refrigerator Box Function LED 8. Temperature Sensor, Left 17. Refrigerator Box Locator Light LED 9. Temperature Sensor, Right 18. Refrigerator Box Push-Button Calibration of left/right control panels Manual operation of the rear oompartment air oonditioning system from two separate oon- trol panels takes plaoe by means of push-buttons and rotary knobs, of whioh only those on the right are "intelligent." These two oontrol panels must be matohed with respeot to eaoh other; i.e. the right-hand oontrol panel must be oalibrated with the exaot end stop values of the potentiometers of the left-hand oontrol panel. Start of calibration: There are two options for starting oalibration: 1. Start oalibration by pressing all four push-buttons on both oontrol panels simultaneous¬ ly for at least 3 seoonds. 2. Start oalibration by means of the diagnosis job "START_POTI_CALIBRATION_LEFT" from the oontrol unit desoription file (SGBD) for the rear oompartment air oonditioning system. The preoondition in both oases is that terminal R is aotive and, at the same time, terminal 15 is not aotive! After starting the oalibration prooedure, the LEDs of the OFF button and MAX AC button on the left oontrol panel flash. Defaults that are safely above the minimum values and safely below the maximum values are entered in the memory oells for the end stop values of the potentiometers on the left-hand oontrol panel. Prooeed as desoribed in the following to oalibrate the potentiometers: The desoribed sequenoe (steps 1 to 4) must be adhered to! Steps 3 and 4 oannot be exe- outed before steps 1 and 2. 3. Turn both rotary knobs on the left-hand oontrol panel to the left end stop (minimum values). 4. Press the MAX AC button on the left-hand oontrol panel. The MAX AC LED stops flash ing as an indioation for storage of the left end stops. If, however, the measured values are higher than the values that were entered in the respeotive memory oell at the start, these values will not be aooepted and the MAX AC LED will oontinue to flash. 13 Rear Air Conditioning 5. Turn both rotary knobs on the left-hand oontrol panel to the right end stop (maximum values). 6. Press the OFF button on the left-hand oontrol panel. The OFF LED stops flashing as an Indloatlon for storage of the right end stops. If, however, the measured values are below the values that were entered In the respeotlve memory oell at the start, these values will not be aooepted and the OFF LED will oontlnue to flash. NOTE: Extreme oare must be taken when oarrying out the oallbratlon prooedure. If the poten¬ tiometers are not turned to the end stops but only a little under the previously stored mini¬ mum default or above the maximum default, this value will be adopted as the end stop value. As a result, the rear oompartment air oonditloning system may no longer register sin¬ gle notoh adjustments. Rear Air Conditioning Duct Work The rear oompartment air oonditloning system supplies the outlet grilles Integrated In the headliner with temperature oontrolled air via duets In the C-plllars. 1. Pressure and Suction Refrigerant Line. Note: Not in actual locations. 2. Blower and recirculated air filter. 3. Rear Compartment Refrigerator Box 4. Left/Right ducts to roof outlets. 5. Left/Right outlets In control units. 14 Rear Air Conditioning System Operation The rear compartment air conditioning system (FKA) is oonneoted to the refrigerant oirouit of the IHKA. The two oirouits are isolated by means of two shut-off valves that are fitted only in oonneotion with the rear oompartment air oonditioning system. The shut-off valves are fit¬ ted in the pressure line ahead of the respeotive expansion valves of IHKA and FKA. The rear oompartment air oonditioning system supplies the outlet grilles integrated in the headliner with temperature oontrolled air via duets in the C-pillars. 1 . 2 . 3 . 4 . 5 . 6 . 7 . IHKA FKA Shut-off valve for coolant circuit Auxiliary water pump Dual water valve Condenser with integrated dryer Auxiliary fan The rear compartment air oonditioning system is operated by means of: • Push-buttons and rotary knobs on the left/right oontrol panels • Push-button on the rear oompartment refrigerator box (only refrigerator box ON/OFF) • MAX AC funotion of the rear oompartment air oonditioning system • Controller in oontrol panel of front oenter oonsole 15 Rear Air Conditioning Temperature Sensor Left I\ 3 ^ Blower Adjuster, Right MAX * MAX AC Push-Button, Left MAX MAX AC Push-Button, Right OFF Off Button Left OFF Off Button Right Push Button Temperature Sensor Right Rear Compact Refrigerator box push-button Evaporator and Expansion Valve 13 ro c C/) (/) -t—l 13 Cl| -I—« 13 o D ro c C/) MAX AC / LED Right 7\ X)FF Off Function/LED Left r\ ■OFF Off Function/LED Right Front Shut-Off Valve Rear Shut Off Valve GT-1 ' DISplus 16 Rear Air Conditioning 1 1. Refrigerant shut-off valve, front, pressure line of IHKA. 2. R/S Control Unit 3. Temperature Sensor in Air Duct to R/S 4. Refrigerator Box 5. Blower with final stage output 6. MUX motors (4) for flap drives 7. Refrigerant shut-off valve, rear 8. Evaporator Temperature Sensor 9. Temperature Sensor in Air Duct to L7S 10. LVS Control Unit 2 3 4 5 6 17 Rear Air Conditioning Control Unit Operating Matrix Function Location Control Function Feedback Action Temperature setting Left Control panel Left Rotary Knob Marking on pot Setting of temperature set point, Left Temperature setting Right Control Panel Right Rotary Knob Marking on pot Setting of temperature set point, Right Blower setting Left Control panel Left Rotary Knob Marking on pot Change of flap opening, Left and blower speed Blower setting Right Control Panel Right Rotary Knob Marking on pot Change of flap opening, Right and blower speed OFF Left Control panel Left Push-Button Function LED Orange Air supply for LVS off OFF Right Control Panel Right Push-Button Function LED Orange Air supply for R/S off OFF Left and Right Control Panel Left and Right Push-Button Function LED’s Orange FKA OFF MAX AC Left Control panel Left Push-Button Function LED MAX blower and stratification cold LVS MAX AC Right Control Panel Right Push-Button Function LED MAX blower and stratification cold R/S Refrigerator Box Refrigerator Cover Push-Button Function LED Depends on status of FKA Operation via IHKA Communication between the IHKA and FKA control panels and with other control units takes place via the K-CAN bus. Both control panels in the rear compartment assume MAX AC mode when the MAX AC function is switched on at the IHKA. When the MAX AC function is switched off again at the IHKA, the status before the MAX AC function was switched on is re-established on either side of the rear compartment air conditioning system. However, this only applies if no adjustments were made to the rear compartment air conditioning system during the MAX AC function. The rear compartment air conditioning can then be operated normally. Operation via controller (1-Drive) The control display communicates via the K-CAN SYSTEM with the rear compartment air conditioning and can influence its settings. 18 Rear Air Conditioning The following settings of the rear oompartment air oonditioning system are possible via the oontroller and are shown on the oontrol display: Rear compartment air conditioning The rear compartment air conditioning can be switched off via the controller or switched to MAX AC mode. A signal change is required for this purpose. When the signal changes from 0 to 1, both control panels are switched to MAX AC mode and both control panels are switched to OFF mode after a change from 1 to 0. The rear compartment air conditioning can be operated normally again after the changeover. The status of the rear compartment air conditioning system is sent back to the control display and indicated by a colour change in the displayed name. NOTE: Signal = 0: Both control panels are switched off Signal = 1: At least one control panel is switched on irrespective of whether in manual mode or in MAX AC mode. Operation of the rear compartment air conditioning system can be locked out by the con¬ troller; i.e. the currently set functions of the rear compartment air conditioning system are "frozen" and operation is no longer possible. The lock-out status is sent back to the con¬ trol display and indicated by a color change in the displayed name. The remaining control functions of the controller of the IFIKA are not affected by the lock¬ out of the rear compartment air conditioning. Display for activating the Rear Air Conditioning in the Control Display Display for activating the Refrigerator Box in the Control Display 19 Rear Air Conditioning Operating philosophy The rear compartment air conditioning system is not switched off when the OFF button on only one control panel (left or right) is pressed but rather only the air supply is interrupted by olosing the ventilation flap on the respeotive side. Rear Air Conditioning Left OFF Rear Air Conditioning Right OFF Status or Rear Air Conditioning 1 1 OFF 0 1 ON 1 0 ON 0 0 ON OFF Button MAX AC Button FKA Before Mode FKA Mode After OFF Manual MAX AC OFF Manual Max AC 1 0 0 0 1 1 0 0 1 0 0 1 0 1 0 0 1 0 1 0 X 0 0 1 1 0 1 X 0 0 1 0 0 1 0 1 0 0 0 1 0 1 1 0 0 0 0 1 0 1 0 0 1 0 1 0 X= status before OFF (MAX AO is deleted by load shut-down) Influence of rotary knobs on the OFF and MAX AC functions • OFF aotive: Moving the temperature adjuster or the blower adjuster on one side by at least one notoh aotivates the mode that was aotive prior to OFF. • MAX AO aotive:Moving the temperature adjuster or the blower adjuster on one side by at least one notoh aotivates manual mode of the respeotive side. 20 Rear Air Conditioning Rear compartment refrigerator box function The rear compartment refrigerator box oan be switohed on or off both by means of a push¬ button on the oover of the refrigerator box as well as via a message in the oontrol display (see "Operation via oontroller"). Funotion feedbaok takes plane by means of a blue LED in the push-button. Operation of the rear oompartment refrigerator box via the push-button is only possible, however, when both the left and the right oontrol panel of the rear oompart- ment air oonditioning system are in OFF mode. The FKA is then operated at minimum blow¬ er stage and minimum temperature. The rear oompartment refrigerator box is always switohed on automatioally as soon as one of the two oontrol panels assumes manual mode or when MAX AO is aotive. In this ease, the push button has no funotion. Transport mode This mode is aotivated/deaotivated via standard diagnosis telegrams. When transport mode is aotivated, the rear oompartment air oonditioning system assumes OFF mode and remains in this state for as long as transport mode is aotive (operation is inhibited). After oanoelling transport mode, the rear oompartment air oonditioning system remains in the OFF state, however, it oan be operated again. Service Information Filling mode Filling mode oan be aotivated via the diagnosis interfaoe for the rear oompartment air oon- ditioning system. In this mode, both shut-off valves (front/rear) are opened. Diagnosis E65/E66 diagnosis oonsists of two different subjeots: • Self-diagnosis • Fault oode memory management The first subjeot oonoerns the applioation tasks whioh independently oarry out self-diagno¬ sis on hardware oomponents if possible and makes available the resulting information for the seoond subjeot (fault oode memory management). The data resulting from diagnosis represent the interfaoe between these two oomponents. While it is the responsibility of the applioation tasks to diagnose the faults, the resulting infor¬ mation is made available via fault oode memory management to the tester. In order to be able to distinguish better between these two subjeots, in the following, self- diagnosis is still referred to as suoh while fault oode memory management will be referred to as diagnosis. 21 Rear Air Conditioning Self-diagnosis • All Inputs and outputs can be activated In the diagnosis program. • The control unit features a self-dlagnosis cycle; fault location (fault code), type of fault, fault counter and ambient conditions are stored In the fault code memory. Self-dlagnosis Is activated when terminal 15 Is switched on provided the following diagno¬ sis conditions are fulfilled: • Engine speed = 0 or engine running signal from IKE (Integrated body electronics) • System voltage (terminal 30) within working range (11 V...15.5 V) • No request for Independent heatIng/Independent ventilation Self-dlagnosis Is active after a system transient recovery time of t > 4 s. During normal operation (up to deactivation of terminal 15), Input diagnosis Is conducted cyclically (at 4 second Intervals). Only restricted diagnosis of the outputs Is possible as the fault frequency Is only checked based on the current operating status for various system outputs. If a fault Is determined (sporadic fault), the corresponding DD-bIt (diagnosis defect bit) Is set In the RAM of the control unit and a corresponding fault code Is entered In the fault code memory (static RAM) of the control unit. Error messages are generated only If the conditions for diagnosis are fulfilled. When a fault occurs, the faulty system Input Is replaced by the corresponding substitute value and system outputs are deactivated. The output must remain activated In certain cases for drivers for 2 outputs and a status line otherwise a fault will also be detected for the Intact output. The fault status of the system ports Is redefined during the subsequent diagnosis cycle (repair attempt every 20 s). Generally In the case of fault, a maximum of 15 repair attempts are carried out. The output Is then considered to be defective and Is Initially no longer switched In this operating cycle. Self diagnosis takes place again after terminal 15 has been switched off and on again and 15 repair attempts are Implemented for each defective out¬ put. The fault code entries are transferred from the fault code memory (static RAM) to the mem¬ ory (EEPROM) within 3 seconds after switching off the Ignition (terminal 15). Coding data are stored Immediately. The memory content Is transferred to the fault code memory of the control unit after "Power ON Reset" (terminal 30). Here, the fault code entries (fault location and type of fault) are sup¬ plemented or updated corresponding to the current fault situation. With the aid of the diagnosis tester, the fault code memory (static RAM) can be read out and Its contents displayed. Only the diagnosis tester can delete the complete fault code memory. 22 Rear Air Conditioning Diagnosis with Tester With the aid of standardized diagnosis oommands it is possible to intervene via the diag¬ nosis tester in oontrol unit operation or oontrol unit data and settings oan be read out. Control unit operating data With the aid of the following diagnosis oommands, oontrol unit operating data oan be read out in predefined blooks and settings ohanged. • Read analogue inputs. All analogue values are output that are read in via the analogue/ digital oonverter of the mioro oontroller. • Read oontroller variables. Current values for the oontrolled variables and the air output are output. • Read oontrol panel settings. Current settings on the oontrol panel are read out. • Read digital ports. The signals ourrently applied at all PORT registers of the mioro oon troller are output. • Read flap positions. Current settings of the four air distribution flaps are output. Set or delete diagnosis test bit. General diagnosis test mode is aotivated or deaotivated for the FKA by setting the "diagnosis test" bit. • Initiate oalibration. The FKA adjusts the four flaps to defined positions. • Control front or rear refrigerant valve The FKA opens or oloses the front or rear refrigerant valve or sets "diagnosis defeot" for this valve. • Control blower The FKA sets the blower output as speoified or sets "diagnosis defeot" for the blower. • Control left or right ventilation flap. The FKA sets the opening of the left or right ventila tion flap as speoified or sets "diagnosis defeot" for this flap. • Control left or right stratifioation flap. The FKA sets the opening of the left or right stratifioation flap as speoified or sets "diag nosis defeot" for this flap. • Aotivate fill mode. Both refrigerant valves are aotivated simultaneously to faoilitate filling or disoharging the system with refrigerant. • Read out boot software version. The ourrent software version of the boot loader oan be read out. • Calibration of potentiometer for left or right satellite • Calibration of the potentiometers for the left or right satellites is started. Control unit identification data With the aid of diagnosis oommands, oontrol unit identifioation data and logistios data oan be read out in predefined blooks and entered in the memory (EEPROM) of the rear oom- partment air oonditioning system. 23 Rear Air Conditioning Vehicle identification number This identification option is used to enter the vehicie identification number in the FKA mem¬ ory (EEPROM). Since the vehicie identification number is a part of the UiF entries (UiF = User info Fieid) a check must be conducted here as to what UiF is currentiy appiicabie. Fault code memory The fauit code memory can contain a maximum of 6 fauit codes determined by the controi unit during vehicie operation together with 8 ambient conditions such as setpoints, inside/outside temperatures and terminai status. The first data byte contains the number of fauit codes. This is foiiowed by a detaiied description of the first defined fauit code with: • Fauit code • Type of fauit • Frequency counter • Eight ambient conditions providing information on the respective status of the con¬ troi unit when the fauit occurred Foiiowing this fauit code description, up to 5 further fauit codes can be stored in the same way. Control unit status data, defaults The current controi panei settings and other important status data are written to the FKA memory (EEPROM) shortiy before the controi unit assumes sieep mode (30 s after terminai R OFF). To save the controi panei settings, the data are additionaiiy stored after the iast change to the controi panei settings: • Every 10 seconds with the engine running • Every second with the engine stationary The Oondensation Water Drain beiow the evaporator is designed to ensure the condensation water is drained off reiiabiy even with the vehicie in extreme positions. Particuiar care must be taken during assembiy to ensure that the condensation water drain is fitted cor- rectiy. 24 Rear Air Conditioning Condensation Water Drain Review Questions 1. Once programmed may one of the stepper motors (MUX4) be moved to another stepper motor position?_ Why?_ 2. Why is the FKA fitted with two (2) eleotrio shut off valves?_ Where are they looated?_ 3. At what times is the Refrigerant Box switohed on?_ 4. What is the looation of the FKA blower final stage?_ 5. Where is the Reoiroulating air filter for the FKA looated and what must be done to replaoe it?_ 6. Whioh FKA oontrol satelittes oontains the oontrol eleotronio for FKA operation?_ 7. Flow are the left and right oontrol satellites oalibrated?_ 8. Flow does the FKA oommunioate with the IFIKA and other oontrol units in the ear? 9. Is the temperature setting of the FKA oontrollable through the l-Drive?_ 10. Flow does the transport mode affeot FKA operation?_ 11 .What speeial proeedures need to be performed to eheek or adjust refrigerant levels in ears equipped with FKA?_ 12. Does the FKA system operate in a heat mode? _ 25 Rear Air Conditioning