To replace a heater core, remove the original heater core, transfer all necessary parts to the new one, put the new core in the correct location and reinstall all essential parts, according to PartSource. Gather antifreeze, distilled water, heater core hoses and hose clamps prior to the job.
To remove the existing heater core, drain the antifreeze and coolant from the radiator, disconnect the air conditioner drain tube from the firewall and unfasten the hose clamps, states PartSource. Access the heater core carefully, and remove its mounting clamps and hoses.
Transfer important parts, such as seals and O-rings, to the replacement core, states PartSource. Install the new core, and reinstall the mounting clamps and hoses that can be accessed from the car’s interior. Reinstall previously removed heater core hoses and the air conditioner drain tube while the front of the car is raised. Next, replace hoses and hose clamps as necessary. Mix appropriate amounts of antifreeze and distilled water, and refill the drain with the mixture after closing the drain.
Lower and start the vehicle, and check for leaks beneath the car and around the heater core while allowing the car to maintain normal operating temperature, says PartSource. Turn the car heater to a high level, and switch on the fan so the heat blows from the heater core. Reattach the heater core access covers after ensuring that all parts are working well.