Four Seasons 74671 HVAC Heater Control Valve

Four Seasons 74671 Heater Valve Overview

The Four Seasons Heater Valve 74671 is an OE replacement HVAC heater control valve built for vacuum-operated temperature control systems. It uses a non-bypass design with two hose connectors and a 0.750 in. (19.050 mm) opening to regulate coolant flow through the heater circuit.

Four Seasons Heater Valve line components are selected for direct-fit HVAC service, and this valve is built with thermoplastic and steel construction for use in temperature control repairs on select Audi, Ford, Lincoln, and Mercury applications.

Key Features

• Vacuum closes non-bypass heater valve design
• OE replacement for factory-style HVAC service
• Two hose connectors for heater circuit connection
• 0.750 in. / 19.050 mm opening size
• Thermoplastic and steel construction
• Vacuum-operated for temperature control systems

Detailed Description

Four Seasons part number 74671 is an HVAC heater control valve used to manage coolant flow to the heater core in vacuum-controlled systems. By opening and closing the heater circuit, it helps maintain proper cabin temperature response in vehicles equipped with a non-bypass valve layout. This OE-style replacement is listed for applications including Audi A6, Audi 100, Audi 80, Audi 90, Audi Coupe Quattro, Ford Escort, Ford Pinto, Lincoln Continental, Mercury Cougar, and related models.

This part cross-references Hayden 5910 for the same application.

What This Heater Valve Helps Address

• Heater output stuck on hot due to a valve that will not close
• Weak or inconsistent cabin heat control
• Coolant flow issues through the heater core circuit
• Vacuum-actuated HVAC temperature control faults
• Replacement needs for worn or leaking heater valves

Installation Notes and Tips

Verify vacuum operation, hose routing, and connector size before installation. Confirm the valve style is non-bypass and that the 0.750 in. opening matches the original part. For best results, inspect heater hoses and vacuum lines for wear during replacement. Fits 1995-1997 Audi A6, N/A; Fits 1995-1997 Audi A6 Quattro, N/A; Fits 1995 Audi S6, N/A; Fits 1989-1994 Audi 100, N/A; Fits 1989-1994 Audi 100 Quattro, N/A; Fits 1992-1994 Audi S4, N/A; Fits 1990-1994 Audi V8 Quattro, N/A; Fits 1988-1992 Audi 80, N/A; Fits 1988-1992 Audi 80 Quattro, N/A; Fits 1989-1991 Audi 200, N/A; Fits 1989-1991 Audi 200 Quattro, N/A; Fits 1988-1991 Audi 90, N/A; Fits 1988-1991 Audi 90 Quattro, N/A; Fits 1990-1991 Audi Coupe Quattro, N/A; Fits 1986-1991 Ford Escort, N/A; Fits 1987-1988 Audi 5000 Quattro, N/A; Fits 1986-1987 Mercury Lynx, N/A; Fits 1983-1984 Audi Quattro, N/A; Fits 1981 Audi Coupe, N/A; Fits 1979-1980 Ford Pinto, N/A; Fits 1979-1980 Lincoln Continental, N/A; Fits 1980 Lincoln Mark VI, N/A; Fits 1977-1980 Lincoln Versailles, N/A; Fits 1979-1980 Mercury Bobcat, N/A; Fits 1979-1980 Mercury Monarch, N/A; Fits 1977-1979 Ford Thunderbird, N/A; Fits 1977-1979 Mercury Cougar, N/A.

Quality Assurance

Four Seasons manufactures HVAC temperature control components for OE replacement service, and this heater valve is built to match the listed application requirements for vacuum-operated systems.