Part description

This heater servo motor is intended for Citroën and Peugeot cars and serves as an important part of the heating and ventilation control system for vehicles with mechanical air conditioning. It is a used original part, which is searched mainly according to product numbers and is suitable as a replacement for a non-functional or worn original part.

The servo motor ensures the movement of the control mechanisms in the heating and air conditioning system. If the original part stops working properly, there may be limited or incorrect control of air distribution or regulation within the heating system. Thanks to the markings A21900100 and 6447KF, the part can be more easily found and compared with the dismantled piece.

Technical information

• Manufacturer: Magneti Marelli
• Model: Peugeot 307
• Other numbers: A21900100, 6447KF, NFP

Product codes

Product codes: 6447KF, A21900100

• Brand: Citroën, Peugeot
• Models from labels/backgrounds: Peugeot 307

Installation recommendations

Since the documents do not contain an exact assembly procedure for a specific car model, generally and typically for this type of electrical part in the heating and ventilation system the following procedure applies. The exact steps may vary depending on the specific design of the car and the approach to the part.

1) Before assembly

• Check that the markings on the new and original part match, especially A21900100 and 6447KF.
• Compare the shape of the connector, the attachment, the position of the mounting points and the design of the output shaft or gear.
• Inspect the condition of the used part for a damaged connector, cracked packaging or excessively worn gears.
• Disconnect the battery before starting work, if this is in accordance with normal service practice for the vehicle in question.

2) Necessary tools and materials

• common hand tools
• set of screwdrivers and heads
• tools for removing interior trim
• flashlight
• contact cleaner and cloth

3) Step-by-step assembly procedure

1. Secure the vehicle against movement and prepare a work area.
2. Dismantle covers or trims that prevent access to the heater servo motor.
3. Find the original part and carefully disconnect the electrical connector.
4. Check the connector and wiring for dirt, looseness, or mechanical damage.
5. Unscrew or release the original servo motor from its hold.
6. Before removing, note the position of the part and the seat of the control part so that the new part can be installed correctly.
7. Compare the dismantled part with the spare part including numbers, connector and mounting.
8. Place the replacement servo motor in place without using excessive force.
9. Fix the part in the original way and make sure it fits correctly.
10. Connect the electrical connector and check that it is firmly seated.
11. Reinstall all covers and removed interior parts.
12. Restore power to vehicle and verify basic function of heating and ventilation controls.
• 4) Post-assembly checks and test drive/function verification
  • Experience heating controls and setting changes that this part handles.
  • Observe that the mechanism moves smoothly, without skipping or unusual noises.
  • Verify that there are no loose covers, connectors or cables after assembly.
  • During normal operation, check that the system responds consistently when changing settings repeatedly.

  5) The most common assembly mistakes + how to avoid them

  • Part interchange based on similar appearance – always compare product numbers and connector.
  • Forcible seating of the motor – the part must fit naturally, without prying or twisting.
  • Damage to the connector – disconnect and connect the connector carefully and without pulling on the cables.
  • Omission of mechanism check – before complete assembly, verify that the control actually works.
  • Assembly without comparing the old and new piece – even similar servo motors may differ in attachment or output position.

  Reasons why the part is damaged

  • normal wear and tear on internal electric motor and gears
  • frequent use of heating and ventilation controls during long-term operation
  • increased resistance in the trailing flap mechanism
  • damage or oxidation of the electrical connector
  • intrusion of dirt or moisture into the component
  • unprofessional prior disassembly or assembly
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