939003705 - L021 REAR PASSENGER TEMPERATURE ADJUSTMENT NOT WORKING (Automatic Air Conditioning)

For the triple zone automatic climate control system only, when the desired temperature for the rear pasengers is set, this temperature is not implemented.
1CHECK ON CORRECT OPERATION OF CLIMATE CONTROL NODEALL OKPROBLEMS ENCOUNTEREDACTION
With the engine running and the compressor switched off, set the control unit to the AUTO function (MONO button off) and adjust the temperature using the rear passenger side temperature knob from cold to hot.Also select the recirculation button to the closed position and set the fan speed to 3-4 bars (display) and the distribution to front ventilation.Using the Examiner, check that the engine temperature has reached at least 70°C.Feel whether the air coming out of the vents varies in temperature (getting hotter).Now carry out the operations to check the passenger compartment cooling function: with the engine running, the ambient temperature around 20°C and the compressor on, set the control unit to AUTO mode, adjust the rear passenger temperature knob from hot to cold up to 16°C, the distribution to the front position, the fan speed to 3 bars and the outside air intake function.After about 5 minutes in these conditions, check using the Examiner that the temperature values for the rear vents have gradually decreased from the initial temperature of about 20°C (ambient temp.) to a temperature of around 6°C.Feel whether the air coming out of the vents varies in temperature (getting colder).End of diagnosis1. The temperature of the air coming out of the vents does not get hotter.1. Move on to Step 2
2. The temperature of the air coming out of the vents does not get colder.2. Move on to Step 2
2CHECK USING DIAGNOSTIC EQUIPMENTALL OKPROBLEMS ENCOUNTEREDACTION
Connect the Examiner diagnostic equipment and check:

  • that there are no errors at the rear passenger air mixture actuator;
  • that there are no faults in the outside temperature sensor;
  • that there are no faults in the passenger compartment temperature sensor;
  • that there are no faults in the solar sensor.
Move on to Step 31. Short circuit to earth error at the rear air mixture actuator.1. Check that the Lin Bus cables are not caught between the metal parts (pay particular attention to the gearbox bolts) and move on to Step 4.
2. Short circuit to +12V error at the rear air mixture actuator.2. Check that the Lin Bus cables are not caught between the metal parts (pay particular attention to the gearbox bolts) and move on to Step 4.
3. Mechanical interference / stuck error at the rear air mixture actuator3. Move on to Step 6
4. Error at the outside temperature sensor.4. Move on to Step 4
5. Error at the passenger compartment temperature sensor.5. Move on to Step 4
6. Error at the solar sensor.6. Move on to Step 4
3CHECKS USING DIAGNOSTIC EQUIPMENTALL OKPROBLEMS ENCOUNTEREDACTION
Keeping the Examiner diagnostic equipment connected, check the correct operation of the air mixture actuator through active diagnosisEnd of diagnosisAir mixture actuator not workingMove on to Step 4.
4ELECTRICAL CIRCUIT CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check the continuity/insulation of the electrical connection between the climate control node and the rear passenger air mixture actuator and the treated air sensors and the outside temperature sensor and the passenger compartment sensor and the solar sensor.Check whether the electrical wiring is loose, disconnect the connectors, visually inspect for any damage to the connectors reconnecting the connectors to the climate control node, the rear passenger air mixture actuator, the outside temperature sensor and the solar sensorMove on to Step 51.Electrical connection broken or not insulated.1.Restore the continuity/insulation of the electrical connection.
2. Electrical connection loose or damaged.2. Refit the electrical connections correctly.
3. Outside temperature sensor not working.3. Replace the outside temperature sensor    Op. 7005R30 ELECTRICALLY CONTROLLED DOOR MIRROR (ONE) - R+R
4. Solar sensor not working.4. Replace the solar sensor    Op. 5010D56 SOLAR SENSOR - R.R FOLLOWING ELECTRICAL SYSTEM CHECK
5. Passenger compartment temperature sensor not working.5. Replace the climate control system control unitOp. 5040D15
6. Rear mixture actuator not working.6. Replace the rear mixture actuator.
5CHECK ON CORRECT OPERATION OF MIXTURE ACTUATORALL OKPROBLEMS ENCOUNTEREDACTION
Check whether the electrical wiring connections are loose.Disconnect and visually inspect for damage at the connector contacts and reconnect the connection to the motor mounting.If it persists, before replacing the actuator, check its operation by manually activating the function that the actuator should carry out.With the engine running, switch on the fan at maximum speed.Place the flaps in the various distribution positions via the control/control unit (manually).Check the air flow in the passenger compartment with your hand at the vents.End of diagnosis1. Electrical connections loose or damaged.1. Renew the electrical connections    See E6020 AIR CONDITIONING
2. There is no air flow intake into the passenger compartment through the vents.2. Move on to Step 6.
6CHECK ON IMPEDIMENTS TO THE ROTATION OF THE MIXTURE ACTUATORALL OKPROBLEMS ENCOUNTEREDACTION
Remove the actuator and check through the control unit that the actuator turns checking for the presence of mechanical impediments to its rotationEnd of diagnosis1.The actuator does not turn.1.Replace the mixture actuator Op.  
2.Kinematic components of flaps broken/stuck.2.Replace the components that is faulty.