How to Replace the Heater Core on Ford Cars

by Contributing Writer; Updated June 12, 2017

Engine coolant runs through the Ford car heater core. Air passes through the core and then into the cabin of the truck, keeping it warm. Unlike the case with most cars, the Ford car heater core is located behind the glove compartment, making it easier to access and replace. You can tell that your truck´s heater core needs to be replaced when the cabin no longer stays warm, even with the heat on at its maximum level.

Under The Hood:

 How to Replace the Heater Core on a 1994 Ford Ranger 4.0

Turn off the engine, open the hood and remove the battery cable from the negative terminal. Make sure the engine is cool.

Attach a 3/8-inch interior diameter hose to the drain outlet on the bottom rear corner of the radiator on the driver's side, and place the bottom end in a resealable plastic container. Turn the drain valve (located above the drain outlet) counterclockwise with a pair of pliers. Drain the engine coolant into the resealable container, then close the valve by turning it clockwise. Remove the hose from the outlet.

Loosen the hose clamps on the radiator hoses where they attach to the heater core on the firewall. Remove the hoses.

Unscrew the screws holding the underdash cover in place on the driver's side of the passenger compartment. Remove the underdash cover.

Unscrew the four screws on the cylindrical heater core access cover and remove it. Remove the heater core by pulling it down and toward the rear of the vehicle. Replace the unit with a new heater core.

Reinstall the heater core access cover and screw in the retaining screws. Replace the underdash cover and screw it into place.

Replace the radiator hoses on the heater core in the engine compartment. Tighten the hose clamps. Add coolant until the level is between the minimum and maximum marks on the reservoir.

Replace the battery cable and start the engine. Check the system for leaks.

Items you will need

  • Wrench set

  • 3/8-inch interior diameter hose

  • Sealed storage container

  • Pliers

  • Phillips screwdriver

  • Radiator coolant

 How to Replace the Heater Core in a 1997 Ford Escort

Disconnect the Escort's negative battery cable to shut off the power. Drain the cooling system, pouring the coolant into a clean container for reuse. Turn the front wheels so they face straight ahead and lock the steering column.

Open the hood and disconnect the heater hoses from the heater core.

Remove the steering wheel from its column. Disconnect the airbag module from the wheel first by removing its bolts, lifting it off the wheel and disconnecting its electrical connectors. Remove the passenger airbag by disconnecting the bolts and connector within the glove box. Place both modules somewhere safe with their fronts facing upward.

Detach the instrument panel from inside the car. You must remove the floor console and all adjacent trim panels, disconnect the Powertrain Control module and hood release handle, lower the steering column and disconnect all electrical connectors on the instrument panel. Remove all the instrument panel support bolts and pull the panel off the car.

Disconnect the antenna lead from the heater core housing, the vacuum control motor vacuum connector and the vacuum lines from the evaporator housing. Disconnect the defroster nozzle connectors and remove the clamp screw on the air-conditioning evaporator outlet duct.

Open the heater core housing by removing all its nuts. Take out the heater dash panel seal, open the heater core cover and remove the core.

Install the new heater core in the core housing and reassemble the housing. Reconnect all connectors to the heater core housing, evaporator and defroster.

Reassemble the entire instrument panel, steering column and airbag modules. Connect the heater hoses to the core, refill the cooling system and reconnect the battery cable.

Run the engine to its normal temperature and check for leaks in the climate control system.

Items you will need

  • Heater core Screwdriver Wrenches Clean container

 How to Replace a Heater Core in a 2003 Ford Taurus

Accessing the Heater Core

Discharge the air conditioning system at your Ford dealer's service department or an automotive air conditioning shop.

Disconnect the car's negative battery cable.

Drain the engine coolant into a large container at the radiator's drain plug--you may need pliers to remove the plug--then drain the remaining coolant at the engine block drain plug.

Remove the instrument panel from inside the car--this will involve removing the center console, stereo, heater/air conditioner controls, steering column and trim panels. Pull off the vent screen from the passenger side cowl.

Removing the Core

Loosen the clamps for the heater hoses with pliers and disconnect them from the core's tubes; these are mounted on the firewall within the engine compartment. Plug the tubes with rubber plugs.

Remove the mounting screws for the white, rectangular-shaped blend door actuator with a hex screwdriver, unplug its electrical connector and remove it from the air conditioner evaporator.

Disconnect the spring on the heater core cover using a small, flat head screwdriver on the spring's hooked end. Depress the locking ramp and remove the short lever on the temperature control door shaft using the same screwdriver, then rotate the door shaft downward and remove the metal link at the lower end.

Remove the three small mounting screws on the heater core cover with a hex screwdriver, lift the lever up and remove the cover and its gasket from the housing.

Pull the heater core from the housing.

Installing the Core

Remove the foam seal from the old heater core and transfer it to the new one then insert the replacement core into the housing.

Close the cover to the heater core housing using the three screws, close the door shaft with its metal link, the locking ramp and the spring.

Reconnect the blend door actuator to the evaporator housing with its screws and reinstall its electrical connector.

Unplug the heater tubes at the firewall and reconnect the heater hoses with their clamps.

Reinstall the entire instrument panel and its components in the reverse order of removal.

Reconnect the negative battery cable and refill the cooling system; use a fresh mix of water/antifreeze if the old coolant is contaminated.

Evacuate and recharge the air conditioning system at the same location that it was discharged.

Items you will need

  • Pliers

  • Rubber plugs

  • Hex screwdriver

  • Flat head screwdriver

  • Antifreeze

 How to Replace the Heater Core in a 1998 Ford F-150

Raise the hood of the truck and disconnect the cable from the battery´s negative terminal -- this will keep any electrical circuits from being completed while you are replacing the heater core.

Position a drain pan under the truck´s radiator and then remove the plug on the underside of the radiator. After all of the coolant has drained from the radiator, replace the plug and set the drain pan aside. On the firewall of the truck, find the heater hoses that connect to the heater core -- they are located on the passenger side. Use pliers to disconnect the heater hoses from the heater core.

Remove the screws that secure the glove compartment to the truck´s dashboard. With the screws removed, pull the glove compartment out and locate the heater core directly behind the glove compartment. The heater core is also held in place with screws -- use a screwdriver to remove them and then slide the heater core out and replace it with a new one. Secure the new heater core with screws and then re-install the glove compartment.

Re-connect the heater hoses to the new heater core (through the firewall, under the hood). Fill the radiator with the coolant that you drained in Step 1 and then re-connect the cable to the battery´s negative terminal.

Items you will need

  • Socket wrench

  • Drain pan

  • Screwdriver

 How to Replace the Heater Core in a Ford Focus

Drain the Focus' cooling system and air conditioner. Make sure you recover at least the air conditioner refrigerant. Disconnect the cable from the negative battery terminal.

Disassemble the dashboard and remove it with an assistant's help. This includes disconnecting the radio, steering wheel, glove compartment, ash tray, air bags, center console, defroster tubes and all trim panels, bolts and retaining screws.

Disconnect the hoses/lines to the heater, A/C evaporator and rear footwell vent along with the cross vehicle beam and heater housing wiring harness. Remove the heater housing by disconnecting all fasteners and remove the core from the housing.

Install the new heater core. Install the heater housing back into the engine compartment and connect the wiring harness, cross vehicle beam and all hoses/lines.

Reinstall the instrument panel (again, with an assistant's help) and reconnect all components, including the center console, air bags, glove compartment, steering wheel and radio.

Reconnect the negative battery cable. Refill the cooling system and recharge the air conditioning system. Start up the engine, and check for any leaks within the system.

Items you will need

  • Replacement heater core

  • Clean containers

  • Wrench

  • Screwdriver

 How to Replace a Heater Core on a 2000 F150

Open the hood and disconnect the negative battery cable from the battery by loosening the terminal nut with a wrench. Wait five minutes to allow the airbag system to fully discharge. Then, drain the engine coolant. Disconnect the lower radiator hose and allow all of the engine coolant to run out into a drain pan.

Remove the antenna. Remove the black plastic cap that covers the antenna mounting plate and then remove the three screws connecting the antenna. Carefully pull up on the antenna to expose the antenna cable. Disconnect the cable from the antenna.

Remove dashboard components. Remove the steering column top cover and fuse panel cover by gently prying them loose. Remove the hood latch release handle by removing the two screws holding it in place. Remove the parking-brake release lever by removing the two screws holding it in place. Remove the floor duct cover by gently prying it loose. Remove the two screws fastening the diagnostic port to the steering column cover. Remove the backing plate on the port by gently prying or pulling it off. Remove the diagnostic port. Remove the instrument panel steering column cover (it is held in place by six screws). Remove the driver- and passenger-side scuff plates and trim panels by prying them loose. Remove the assist handles and A-pillar trim panels on the driver and passenger sides by unfastening the two retaining nuts.

Disconnect wiring. Disconnect the brake on/off switch connector, located just above the brake pedal. Disconnect all electrical connectors behind the panel. The final connector is behind the glove box, closer to the firewall. After the connectors have been disconnected, carefully remove any Christmas tree clips holding the wire harnesses to the truck body. Remove the ground wires that are secured with two screws. Locate the antenna wire that leads in from the radio area of the dash and exits the cab through a grommet. Pull the grommet out of the hole and carefully pull the antenna cable through. Carefully remove the Christmas tree clip attaching the cable to the dash just below the glove box. Remove the opening cover reinforcement from the steering column and disconnect the connectors by removing four screws holding the cover in place.

Remove dashboard components. Remove the four screws holding the steering column in place and lower the column to the seat. Do not remove any wiring attached to the steering column. Remove the instrument-panel relay cover by prying it loose. Remove the instrument panel bolts through the steering column opening.

Remove the instrument-panel reinforcement bolt. Disconnect the right-hand instrument-panel main harness connectors. Remove the instrument panel bolts through the passenger side air bag module opening. Remove the instrument-panel reinforcement bolt and the upper instrument panel floor brace bolt. Remove the entire dashboard assembly.

Remove the heater core. Disconnect the hose couplings from the heater core. Remove the A/C plenum demister adapter. Remove the screws and move aside the relay bracket. Disconnect the vacuum line. Remove the 15 bolts from the upper plenum casing and remove the upper plenum casing. Remove the blend door assembly from the case. Finally, remove the heater core from the case.

Items you will need

  • Full set of US and Metric wrenches and sockets

  • Replacement heater core

  • Drain pan

 How to Replace a Heater Core for a Ford Ranger

Draining the Cooling System

Disconnect the ground cable from the negative battery terminal. Loosen the retaining bolt using a wrench. Then pull the clamp off the terminal.

Locate the petcock valve on the lower right corner of the radiator and place a waste oil collection pan underneath it.

Open the petcock valve by turning it counterclockwise with needle nose pliers.

Close the petcock valve by turning it clockwise with the needle nose pliers after all the coolant has drained out.

Removing the Heater Core

Loosen the two hose clamps that secure the heater hoses to the heater core inlet and outlet tubes using a Phillips screwdriver. The inlet and outlet tubes will be located in the engine bay, at the firewall, on the passenger side of the vehicle.

Pull out the heater hoses of the heater core inlet and outlet tubes with your hands.

Remove the five screws that connect the heater core access panel to the heater duct using a socket. The access panel will be located underneath the dash on the passenger side of the vehicle.

Pull the access panel away from the heater duct.

Pull the heater core downward and towards the rear of the vehicle to remove it from the heater duct. Then remove it from the vehicle.

Installing the Heater Core

Slide the new heater core upward into the heater duct. Be sure to guide the inlet and outlet tubes through the holes in the firewall.

Place the heater core access panel into position over the heater duct.

Screw in the five screws that secure the access panel to the heater duct using a socket.

Slide the heater hoses onto the inlet and outlet tubes on the heater core.

Refilling the Cooling System

Tighten the hose clamps on the inlet and outlet tubes using a Phillips screwdriver.

Fill the radiator with a 50/50 mix of fresh antifreeze and water.

Run the engine and visually inspect for leaks.

Items you will need

  • Wrench set

  • Waste oil collection pan

  • Needle nose pliers

  • Phillips screwdriver

  • Socket set

  • Antifreeze

  • Water

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.