How To Replace Heater Core

If your car is no longer delivering heat when you turn the heating system on, it may be time to learn how to replace the heater core. Typically, when the heat system is no longer delivering hot air, the heater core is the source. Learning how to replace the heater core is not a very complicated process although it will take some time and a standard tool set. The process may vary from vehicle to vehicle, however the general idea is the same.

Things you'll need:

  • Standard tool set
  1. Drain the cooling system. Drain the radiator of all coolant and water. Draining the cooling system will make the entire process easier and keep the process more organized and clean.
  2. Expose the heater core. Start by removing the top of the dashboard on the passenger's side. Typically, the dashboard is secured by screws under the top lip of the dashboard or inside the air vents on some vehicles. Remove the screws on the underside of the dashboard as well to allow access to the heater core.
  3. Identify the heater core. Look below the dashboard on the passenger side of the vehicle. Locate the plastic box which contains the heater core. Typically, the plastic box is white.
  4. Free the heater core. Free the heater core from the plastic box by loosening all the screws attached the box. There should be one screw in particular which is hard to remove and will be located on the top. You must free this screw to release the plastic box. The heater core will now be directly exposed. Remove any remaining screws and the steel clamp holding the heater core in place.
  5. Pull the heater core loose. First lay down plastic or sheeting to protect the floor. Pull the heater core loose by gentle wiggling it out of place. Any remaining coolant or water may spill out.
  6. Install the new heater core. Patiently install the new heater core. This process may take several tries to get everything positioned correctly.
  7. Replace the screws and clamp. Replace the screws and the clamp that secure the heater core. Replace the plastic box that houses the heater core and any remaining screws.
  8. Refill coolant. Refill the coolant and water in the vehicles cooling system.
  9. Test the heater core. Turn the heating system on and wait patiently. Check for any leaks from the newly installed heater core. Ensure the heating system is producing heat.
  10. Replace the dashboard. Replace the dashboard and any associate screws. Do not forget the vent screws.


  • Bend the hoses from the heater core to get them to pass through the firewall.
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