Four Seasons 98780 HVAC Heater Core

Four Seasons 98780 Heater Core Overview

Four Seasons 98780 is an aluminum HVAC heater core built for direct replacement in select Mitsubishi and Plymouth applications. It is sized for the factory heater core location and meets or exceeds OEM requirements for the listed vehicles.

Compatible with 1989-1993 Mitsubishi Galant, 1990-1994 Mitsubishi Eclipse, and 1990-1994 Plymouth Laser, this Four Seasons Heater Core supports reliable cabin heat performance in vehicles that need a precise fit and proper coolant flow through the HVAC system.

Key Features

• Brand: Four Seasons Heater Core
• Part number: 98780
• Aluminum heater core construction
• Meets or exceeds OEM specifications
• Core dimensions: 7-3/4 in. length, 6-3/8 in. width, 1-1/4 in. thickness
• Tube size: 0.625 in. / 15.875 mm on both connections
• Direct-fit HVAC heater core for listed Mitsubishi and Plymouth models

Product Details

The Four Seasons 98780 heater core is an aluminum HVAC core designed around the factory dimensions of the original unit. With a core height of 7.750 in., core width of 6.375 in., and core depth of 1.250 in., it is built to match the space and connection layout used in the vehicle’s heater box. This part is a practical replacement choice for drivers servicing a Mitsubishi Galant, Mitsubishi Eclipse, or Plymouth Laser with heater performance concerns.

Four Seasons Heater Core products are positioned as replacement HVAC components for repair work where accurate sizing and dependable heat transfer matter. Part number 98780 is also referenced under Four Seasons 26803 for the same application.

Common Issues This Part Can Address

• Weak or inconsistent cabin heat
• Coolant odor inside the vehicle
• Leaking heater core causing interior moisture
• Restricted coolant flow through the HVAC heater circuit
• Loss of defrost performance due to poor heater output

Installation Notes

Verify the vehicle year, make, and model before installation. Confirm the heater core dimensions and tube size match the original unit, especially on 1989-1993 Mitsubishi Galant, 1990-1994 Mitsubishi Eclipse, and 1990-1994 Plymouth Laser applications. Because heater core replacement typically requires access to the HVAC case, inspect related hoses, clamps, and coolant condition during service.

Adjustable pipe positioning is not provided on this part, so alignment should be checked against the factory routing before final assembly.

Quality Assurance

This heater core meets or exceeds OEM requirements for the listed applications. Four Seasons 98780 is built as an aluminum heater core for replacement use in factory-equivalent HVAC service.