Four Seasons 74774 HVAC Heater Control Valve

Four Seasons 74774 Heater Valve Overview

Four Seasons 74774 is an OE replacement HVAC heater control valve for vacuum-operated heater systems. It uses a non-bypass design with a steel body and three hose connectors, with 0.625 in. (15.875 mm) openings for a direct-fit service replacement.

Compatible with select Jeep heating systems, this heater valve is built for 1987-1992 Jeep Comanche, 1987-1990 Jeep Cherokee, 1987-1990 Jeep Wagoneer, and 1987 Jeep J10 applications. If you are replacing a vacuum closes non-bypass heater valve, Four Seasons 74774 provides the correct style and connection layout for the listed vehicles.

Key Features

• Part number: 74774
• Vacuum-operated heater control valve
• Non-bypass style
• Steel construction
• Three hose connectors
• 0.625 in. / 15.875 mm openings
• OE replacement design

Product Details

Four Seasons Heater Valve line focuses on HVAC temperature control components for service replacement applications. This heater valve is a vacuum-closing, non-bypass unit that regulates coolant flow through the heater circuit based on system vacuum. It is specified for Jeep Comanche, Cherokee, Wagoneer, and J10 models listed in the fitment data, making it a targeted solution for restoring heater control function in those vehicles. This part cross-references UAC HV9503C for the same application.

Common Problems This Part Can Address

• Heater output stuck on or stuck off
• Coolant flow not responding to vacuum control
• Leaking or corroded heater valve housing
• Incorrect hose connection size or layout during replacement
• Loss of cabin temperature control in Jeep heating systems

Installation Notes and Tips

• Verify vacuum operation before installation to confirm the valve opens and closes correctly.
• Match the 3-connector hose routing to the original HVAC plumbing on the vehicle.
• Confirm the 0.625 in. openings against the existing heater hoses before assembly.
• Inspect nearby hoses and clamps for wear while servicing the heater valve.
• Bleed the cooling system after installation to restore proper heater performance.

Quality Assurance

Four Seasons 74774 is an OE replacement heater valve built to match the listed application requirements for fit, operation type, and connector configuration.