Description
Heater Fan Regulator for Citroën AX, Saxo, Xantia, XM, Berlingo, Xsara, ZX and Peugeot 106, 405, 406, 605 and Partner
This heater fan regulator (blower motor regulator) is designed for a range of Citroën and Peugeot models and is commonly referenced under the part number 644178. It controls the speed of the vehicle’s heater/ventilation fan and restores stepped or variable fan speed control when the original regulator has failed. The unit is aimed at professional mechanics and competent DIY enthusiasts who maintain or repair PSA (Citroën/Peugeot) HVAC systems.
Function and Symptoms
The regulator modulates the current to the blower motor to provide selectable fan speeds. Typical symptoms of a failing regulator include loss of one or more fan speeds, fan only working at full speed, intermittent fan operation, or no fan operation at all. Faulty regulators may also cause unusual noise or overheating in the HVAC housing.
Compatibility and Fitment
Fits the following models (common applications): Citroën AX, Saxo, Xantia, XM, Berlingo, Xsara, ZX; Peugeot 106, 405, 406, 605, Partner. Always check the part number 644178 against the vehicle’s existing component to confirm fitment.
Technical Information
- Manufacturer: Stellantis / Citroën / Peugeot
- Model: Heater Fan Regulator / Blower Motor Regulator
- Product Codes: 644178
- Other Numbers: Not provided
Replacement Procedure (General Guidance)
- Park the vehicle on level ground, switch off ignition and remove the ignition key.
- Disconnect the negative battery terminal before starting work to prevent short circuits.
- Access the regulator—on many PSA models it is located in or behind the HVAC housing, often accessible via the glovebox or an under-dash panel.
- Disconnect the electrical connector, remove retaining screws or clips and extract the faulty regulator; compare the unit and connector to the new part.
- Fit the new regulator, secure mounting screws, reconnect the electrical plug and the battery, then test all fan speeds and HVAC functions.
- If uncertain about access or electrical connections, consult the vehicle repair manual or seek professional assistance.
Installation Recommendations
- Always disconnect the battery before removal and installation.
- Inspect the blower motor and wiring harness for wear, corrosion or contamination—high current draw from a failing blower motor can damage a new regulator.
- Clean connectors and ensure good contact; replace any brittle or corroded wiring or plugs.
- Verify full function of all fan speed settings after installation and check for abnormal heat or smells from the HVAC ducting.
Most Common Failure Reasons
- Wear and thermal stress from prolonged operation and high current loads.
- Corrosion or poor electrical contact at the connector due to moisture ingress.
- Excessive current draw caused by a failing or obstructed blower motor (bearing wear or debris).
- Mechanical damage from improper handling or servicing of HVAC components.
Designed for professionals and experienced DIYers, this heater fan regulator is an effective replacement for restoring proper ventilation control in affected Citroën and Peugeot models. The part number 644178 is commonly used when searching for compatible replacements.
