Four Seasons 73121 HVAC Recirculation Door Actuator

Four Seasons 73121 Air Door Actuator

The Four Seasons 73121 HVAC recirculation door actuator restores control of the air door in vehicles equipped with Automatic Temperature Control (ATC). Built as a cam-style HVAC air door actuator with a 5-terminal pin layout and 3 mounting ears, it is made for precise movement within the climate control system.

Use this Four Seasons Air Door Actuator when servicing HVAC systems in the Volkswagen Passat, Audi A4, Audi A4 Quattro, Audi S4, and Audi S3. The 73121 part number is a direct reference for buyers searching for an HVAC recirculation door actuator for ATC-equipped applications.

Key Features

• HVAC recirculation door actuator for climate control air door operation
• Cam door linkage for controlled actuator movement
• 5-terminal pin configuration
• 3 mounting ears for secure installation
• Four Seasons Air Door Actuator line for HVAC service applications

Fitment Details

• Fits 1998-2005 Volkswagen Passat, N/A, with HVAC systems featuring Automatic Temperature Control (ATC).
• Fits 1997-2002 Audi A4, N/A, with HVAC systems featuring Automatic Temperature Control (ATC).
• Fits 1997-2002 Audi A4 Quattro, N/A, with HVAC systems featuring Automatic Temperature Control (ATC).
• Fits 2000-2002 Audi S4, N/A, with HVAC systems featuring Automatic Temperature Control (ATC).
• Fits 2000 Audi S3, N/A, with HVAC systems featuring Automatic Temperature Control (ATC).

What It Helps Fix

• Recirculation door that does not respond to HVAC commands
• Inconsistent cabin air routing between fresh and recirculated air
• Temperature control issues caused by a failed air door actuator
• HVAC system noise related to worn actuator linkage or internal movement
• Loss of proper ATC function in the climate control system

Installation Notes and Tips

Confirm the vehicle uses Automatic Temperature Control (ATC) before ordering. Verify the connector style, mounting ear layout, and cam linkage match the original unit on the Volkswagen Passat, Audi A4, Audi A4 Quattro, Audi S4, or Audi S3. This part cross-references Global Parts Distributors LLC 1712281 for the same application.

Quality Assurance

Four Seasons supplies HVAC service parts for climate control repair applications. Part number 73121 is listed with direct interchange references, including OE-style numbers used in the same application family, which helps support accurate replacement selection.