Four Seasons 90774 HVAC Heater Core

Four Seasons 90774 Heater Core Overview

The Four Seasons 90774 heater core is an aluminum HVAC heater core built for direct replacement service in select Ford, Mercury, and Lincoln applications. It is sized at 7-3/8 inches long, 5-7/8 inches wide, and 1-7/8 inches thick, with 3/4-inch inlet and outlet tubes for a precise fit in the heater box.

Compatible with 1993-1996 Lincoln Mark VIII, 1994-1997 Ford Thunderbird, 1994-1997 Mercury Cougar, and 1994-1995 Ford Cougar, this heater core is an OE-style replacement for vehicles that need dependable cabin heat and stable coolant flow through the HVAC system. The Four Seasons Heater Core line focuses on direct-fit thermal components for service repairs, and part number 90774 follows that approach with aluminum construction and OEM-matching dimensions.

Key Features

• Aluminum heater core construction
• Dimensions: 7-3/8 in. length, 5-7/8 in. width, 1-7/8 in. thickness
• Core height: 7.375 in.; core width: 5.875 in.; core depth: 1.875 in.
• 3/4 in. tube size on both connections
• Meets or exceeds OEM requirements
• Direct replacement style for select Ford, Mercury, and Lincoln HVAC systems

Detailed Description

Four Seasons part number 90774 is an aluminum heater core designed for vehicles that rely on a compact, OE-shaped core assembly inside the HVAC case. Its aluminum core material supports efficient heat transfer, while the fixed pipe positioning and listed tube dimensions help ensure proper alignment during replacement. This heater core is a practical choice when servicing a leaking, restricted, or heat-limited cabin heater circuit in a 1993-1996 Lincoln Mark VIII, 1994-1997 Ford Thunderbird, 1994-1997 Mercury Cougar, or 1994-1995 Ford Cougar.

This part cross-references APDI 9010245 for the same application.

What It Helps Fix

• Weak or inconsistent cabin heat
• Coolant seepage from a damaged heater core
• Restricted coolant flow through the HVAC heater circuit
• Fogging or sweet coolant odor caused by heater core leakage
• HVAC performance loss from an aging internal heat exchanger

Installation Notes and Tips

Verify the heater core dimensions, tube size, and pipe orientation against the removed unit before installation. Because this is an HVAC heater core, access typically requires removal of interior trim or HVAC case components, so inspect related seals, hoses, and coolant condition during service. Flush the cooling system if contamination or debris is present, and confirm there are no leaks after reassembly.

Quality Assurance

Four Seasons lists this heater core as meeting or exceeding OEM requirements. The Four Seasons Heater Core product line is built for direct-fit HVAC service replacement, and part number 90774 is specified for the listed Ford, Mercury, and Lincoln applications.