Four Seasons 74661 HVAC Heater Control Valve - Rear

Four Seasons 74661 Heater Valve Overview

The Four Seasons Heater Valve 74661 is a cable-operated, open non-bypass HVAC heater control valve built as an OE replacement. It uses a steel body with two hose connectors and a 5/8 in. opening for direct service in the heater hose circuit.

For rear heater applications on Chevrolet G10, G20, and G30 vans, as well as GMC G15, G25, and G35 vans, this valve helps restore proper coolant flow control through the heater system. It also cross-references Monroe Shocks & Struts 173039 for the same application.

Key Features

• Four Seasons Heater Valve line, part number 74661
• Cable-operated open non-bypass design
• Steel construction for HVAC heater service
• Two hose connectors
• 5/8 in. opening, 15.875 mm
• OE replacement heater control valve

Product Details

This HVAC heater control valve is built for vehicles that use cable-actuated temperature control and a non-bypass coolant routing setup. The Four Seasons 74661 is specified for rear heater applications on 1973-1975 Chevrolet and GMC vans, and it also appears in fitment for 1967 Chevrolet Suburban models and the 1961 Pontiac Tempest with 5/8 in. I.D. heater hose. If you are searching for a Four Seasons 74661 heater valve for a Chevrolet G10 rear heater valve or a GMC G25/G2500 van heater control valve, this part matches those listed applications.

The Four Seasons Heater Valve product line focuses on direct-fit HVAC temperature control components, and this valve follows that OE-style approach with the correct cable operation and hose size for the listed vehicles. The part number 74661 is also a useful reference when comparing heater valve replacements for classic Chevrolet and GMC van heating systems.

What It Helps Address

• Heater core flow that does not respond to the temperature cable
• Stuck-open or stuck-closed heater valve operation
• Loss of cabin heat control in rear heater systems
• Coolant routing issues at the heater hose connection
• Replacement needs for worn OE heater control valves

Installation Notes and Tips

• Verify cable operation before installation so the valve opens and closes correctly.
• Confirm the vehicle uses a 5/8 in. heater hose connection and a non-bypass valve layout.
• Match the valve orientation and hose routing to the original HVAC setup.
• Inspect heater hoses and clamps during service to avoid leaks after replacement.
• Use the listed fitment only: Fits 1975 Chevrolet G10, Rear; Fits 1975 Chevrolet G20, Rear; Fits 1975 Chevrolet G30, Rear; Fits 1975 GMC G15, Rear; Fits 1975 GMC G25, Rear; Fits 1975 GMC G35, Rear; Fits 1973-1974 GMC G15/G1500 Van, Rear; Fits 1973-1974 GMC G25/G2500 Van, Rear; Fits 1973-1974 GMC G35/G3500 Van, Rear; Fits 1967 Chevrolet C10 Suburban, N/A; Fits 1967 Chevrolet C20 Suburban, N/A; Fits 1967 Chevrolet K10 Suburban, N/A; Fits 1967 Chevrolet K20 Suburban, N/A; Fits 1961 Pontiac Tempest, N/A.

Quality Assurance

Four Seasons is a recognized HVAC parts brand, and this heater valve is listed as an OE replacement for the specified applications. Part number 74661 is cataloged for direct identification and fitment matching on the vehicles shown above.