Four Seasons 74861 HVAC Heater Control Valve - Rear

Four Seasons 74861 Heater Valve Overview

The Four Seasons 74861 heater valve is an OE replacement HVAC heater control valve built for vacuum-operated temperature control. It uses a non-bypass design with two hose connectors and a 0.625 in. (15.875 mm) opening to regulate coolant flow through the heater circuit.

Compatible with rear HVAC applications on 1993-1995 Chevrolet Astro and 1993-1995 GMC Safari, this Four Seasons Heater Valve line part is a direct-fit service component for restoring cabin heat control. The 74861 part number is also referenced in common aftermarket cross-reference listings for the same application.

Key Features

• Vacuum open heater valve for HVAC temperature control
• Non-bypass style for direct coolant flow management
• Plastic construction
• Two hose connectors
• 0.625 in. / 15.875 mm opening size
• OE replacement design

Detailed Product Description

Four Seasons 74861 is a vacuum-operated HVAC heater control valve used to open and close coolant flow to the heater core circuit. The non-bypass configuration is intended for systems that require the valve to control flow without routing coolant around the heater core. This makes it a practical replacement for rear HVAC service on Chevrolet Astro and GMC Safari models from 1993 through 1995. If you are searching for a 1993-1995 Chevrolet Astro rear heater valve or a 1993-1995 GMC Safari rear HVAC heater control valve, this part number is a direct match for the listed applications.

This part cross-references MAHLE 5866 for the same application.

What This Heater Valve Helps Address

• No heat from the rear HVAC system
• Heater output stuck on hot or cold
• Coolant flow not responding to vacuum control
• Leaking or cracked heater valve housing
• Restricted heater circuit operation in rear climate control systems

Installation Notes and Tips

Verify vacuum operation, hose routing, and connector size before installation. Match the valve orientation to the existing rear HVAC plumbing on the vehicle, and inspect the surrounding hoses for wear, swelling, or coolant residue while the system is open. Confirm fitment by year, make, model, and rear position before replacing the valve.

Quality Assurance

Four Seasons manufactures HVAC service parts with OE replacement specifications in mind. Part number 74861 is built as a vacuum open, non-bypass heater valve for the listed Chevrolet Astro and GMC Safari rear applications.