Four Seasons 73778 HVAC Mode Door Actuator - Auxiliary

HVAC Mode Door Actuator Overview

The Four Seasons 73778 HVAC mode door actuator is built for climate control systems that need precise air door movement. It is a direct-fit style replacement for compatible applications and is identified by part number 73778.

Compatible With 2016-2023 Mazda CX-9 auxiliary HVAC applications, this actuator uses a cam-style door linkage and a 5-pin terminal layout. The 4-ear mounting design supports secure installation in the HVAC housing.

Key Features

• Cam-style door linkage for controlled air door movement
• HVAC air door actuator construction
• 5-terminal pin configuration
• 4 mounting ears for secure attachment
• Four Seasons part number 73778

Detailed Description

Four Seasons 73778 is an HVAC mode door actuator used to control air distribution inside the climate system. In compatible Mazda CX-9 auxiliary applications, it helps direct airflow to the selected vent mode by moving the internal door through the HVAC case. The cam linkage design and 5-pin electrical connection support accurate actuator operation, while the 4-ear mounting pattern provides a stable fit in the assembly. This part cross-references TK4961A70 for the same application.

What It Is Used For

• Restoring proper airflow direction through the HVAC system
• Addressing inconsistent vent mode selection
• Replacing a worn or nonresponsive air door actuator
• Correcting HVAC doors that do not move as commanded

Installation Notes and Tips

Verify the connector style, mounting ear layout, and cam linkage match the original actuator before installation. Confirm the auxiliary HVAC application on the vehicle and compare the part number 73778 with the removed unit for proper identification.

Quality Assurance

Four Seasons states that its products are engineered and tested for long service life, drawing on more than 50 years of mobile A/C experience.