Solar Sunroof Function
Solar Sunroof Function
• Solar ventilation function only works when the sunroof is either closed or in raised position (the solar sunroof - C - converts solar energy into electrical energy which then passes into the vehicle electrical system via terminals - A - (on the front of the sunroof) and terminals - B - (on the frame of the sunroof).
• Solar operation is not possible when the ignition is switched on and when in auxiliary heater/auxiliary ventilation mode. The fresh air blower control module (J126) interrupts the link between the solar roof and the fresh air blower (V2).
• If fresh air blower solar operation is not desired, the function can be switched off depending on the adaptation at the Climatronic Control Module (J255) A/C control head in the MMI (different versions) => Owner's Manual and => "Infotainment/MMI Owner's Manual".
• The solar operating time for the Fresh Air Blower (V2) is displayed in hours in the Climatronic Control Module (J255) A/C control head measured value block => Vehicle Diagnosis, Testing and Information System VAS 5051 in the "Guided Fault Finding" function.
• Design of Fresh Air Blower Control Module (J126) is such that in solar mode, Fresh Air Blower (V2) is only actuated if there is sufficient energy for solar operation (minimum voltage with Fresh Air Blower (V2) actuated must be greater than 2 V at present).
• The energy supplied by the Solar Cells (C20) is conveyed directly to the Fresh Air Blower (V2) via Fresh Air Blower Control Module (J126). The fresh air blower (V2) converts the generated electrical energy into blower output.
• On vehicles without sunroof with Solar Cells (C20), all A/C system control motors remain standing in their current positions at the moment when the ignition is switched off. However, in order to ventilate the vehicle interior when the system is in solar ventilation mode, the back pressure / fresh air and recirculated air doors must be in the "fresh air" position. Therefore on vehicles with solar roof, the Climatronic Control Module (J255) A/C control head is informed via coding that the vehicle is equipped with solar cells. The Climatronic Control Module (J255) A/C control head then moves the doors in the A/C unit to "fresh air mode" position after ignition is switched off.
• With ignition switched off (no signal detected from the Climatronic Control Module (J255) A/C control head), the Fresh Air Blower Control Module (J126) checks the voltage at the input of the solar cells in regular intervals and converts the voltage generated by the solar cells in such a way that the fresh-air blower runs at the highest possible speed when there is sufficient solar energy.
• The electrical energy transferred from the solar roof at a solar radiation level of 500 W / m2 is approximately 12 W. It is calculated as follows: 500 W / m2(solar irradiation) x 0.21 m2 (solar cell surface area on sunroof) x 0.13 (efficiency of Solar Cells (C20)) x 0.9 (efficiency of Fresh Air Blower Control Module (J126)).
• Terminals - A - and - B - (on the sunroof and sunroof frame) are used to transfer the electrical energy generated, and must always be clean and free of conventional lubricating grease.
• If necessary, terminals - A - and - B - can be lightly coated with contact grease (electrically conductive protective lubricant, available from suppliers of electronic equipment).
Solar Roof, Checking Function
- Place vehicle in direct sunlight.
• If weather conditions are unfavorable, the solar sunroof can be illuminated using two commercially available 1000 W halogen lamps. A distance of at least 500 mm from the solar roof must be maintained. Make sure that all sunroof Solar Cells (C20) are illuminated completely and evenly so that the Solar Cells (C20) can supply sufficient electrical energy to drive the Fresh Air Blower (V2),
• Only an energy of 1.5 W is supplied when shining halogen lamps on the solar sunroof (the fresh air blower (V2) turns, but air flow is difficult to detect).
- Open the "center" instrument panel vents and close the remaining vents.
- If necessary, check the adaptation of the Climatronic Control Module (J255) A/C control head (the "sunroof with solar cells" function has to be adapted) => Vehicle Diagnosis, Testing and Information System VAS 5051 in the "Guided Fault Finding" function.
- Check the setting at the MMI (Multi Media Interface), the "solar operation" function has to be set (different versions) => Owner's Manual and => Owner's Manual"Infotainment / MMI".
- Close sunroof.
- Switch ignition off (the Climatronic Control Module (J255) A/C control head is dark).
A current of air can be felt from the dash panel vents (check by moistening palm of hand if necessary).
If no air flow can be detected:
- Check DTC memory of the Climatronic Control Module (J255) A/C control head => Vehicle Diagnosis, Testing and Information System VAS 5051.
- Check the coding and adaptation of the Climatronic Control Module (J255) A/C control head. => Vehicle diagnosis, testing and information system VAS 5051 in the "guided fault finding" function
• The current, which is sent from the sunroof solar cells (C20) to the fresh air blower (V2), can be read in the measured value block depending on version of the Climatronic control module (J255) A/C control head. Place vehicle in direct sunlight, e.g. with sunroof closed (or beneath two lamps as described above), and select respective measuring value block of front A/C control head, Climatronic Control Module (J255), => Vehicle Diagnosis, Testing and Information System VAS 5051. After switching off the ignition, the current is then displayed which was sent from sunroof with Solar Cells (C20) when switching off the ignition (and the brief period afterward).
- Switch off ignition.
- Remove the plenum chamber cover.
CAUTION!
Even when the engine is cold, both pump/valve unit valves can be hot.
- Open the 3-pin harness connector - A - from the vehicle wire harness to the air intake unit (to the Fresh Air Blower Control Module (J126)).
- Measure voltage at the connector - B - between contact - 2 - (from the solar roof) and contact - 3 - (ground).
• Specification: 8 - 12 V = (depending on intensity of the solar radiation)
- Connect a test lamp (12 V with maximum 5 W) between terminals - 2 - and - 3 - on connector - B -.
- The test lamp should glow or light up (depending on intensity of the solar radiation).
• The solar roof function is OK if test lamp glows or lights up. If the fresh-air blower (V2)does not run, check the Fresh Air Blower (V2) for freedom of movement and actuation of Fresh Air Blower Control Module (J126) by the Climatronic Control Module (J255) A/C control head. If no fault is found, replace the Fresh Air Blower Control Module (J126).
• If test lamp does not glow or light up, check wire connection to both contacts - B - at the sunroof cut-out. If no malfunction can be detected, check the solar panel.
• Only an energy of 1.5 W is supplied when shining halogen lamps on the solar sunroof (the fresh air blower (V2) turns, but air flow is difficult to detect).