Heater Core Replacement

Step by step guide on how to replace an automotive heater core, though each car is different in complexity, these steps outline the basic procedure.

Difficulty Scale: 6 of 10

Tools and Supplies Needed

  • Replacement heater core
  • Coolant
  • Hose clamps
  • Fluid catch basin
  • Socket set
  • Wrench Set
  • Screw driver set
  • Protective eyewear and clothing

Begin with the vehicle on level ground, engine cold, with the emergency brake on.

Step 1 - Locate and remove the negative battery cable, move the cable end far enough away to avoid an accidental connection.

Negative Battery Cable Removal

Step 2 - Release the radiator cap (engine cold), and loosen the radiator drain valve, have a fluid basin ready.

Draining Engine Coolant

Step 3 - Some vehicles utilize a common plenum for both heater core and A/C evaporator core, these types will require the refrigerant be evacuated from the system, once evacuated, disconnect heater hoses and necessary A/C equipment.

Evacuating Refrigerant

Step 4 - Using the hose clamp removal tool, loosen and remove the heater hoses from the heater core inlet and outlet fittings.

Remove Heater Hoses

Step 5 - After the heater hoses have been removed, locate and remove upper dash mounting screws. Remove any mounting hardware across the top of the dash assembly, which is usually covered by pop-in trim pieces along the base of the windshield.

Removing Dash Mounting Screws


Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2015-01-09)