The heater core in your Ford Ranger is a radiator-like device used to heat the vehicle’s cabin. As the hot coolant circulates through the heater core, a flap door opens to expose the heater box, which contains the core, to the cabin of the car. When the heater switch is turned on, a fan activates, and blows hot air into the heater core, and subsequently into the cabin of your vehicle. If your vehicle does not produce hot air to heat the cabin, the core may be defective.
Allow the cooling system to cool completely. Use a thick rag to protect yourself, rotate the radiator cap to the first stop, then step back and release the pressure in the system. Once the pressure is released, drain the cooling system by moving a large container under the radiator drain at the bottom of the radiator and connect a 3/8-inch (9.5 mm) diameter hose to the drain fitting. Open the drain fitting with a pair of pliers and remove the fluid in the pan.
Loosen the clamps on the heating hoses with a screwdriver. Loosen the hose clamps inside the engine compartment on the engine side of the firewall. Turn the hoses and separate the central heating pipes.
Put a plug or cap on the centre tube heater to prevent coolant from spilling into the passenger compartment when you remove the heater core. Place a plastic sheet on the vehicle floor to further protect the interior from coolant spills.
For 1994 and earlier Ford Ranger models, remove the four screws securing the heater core access cover on the passenger side interior. Carefully remove the heater base at the rear and pull down to remove. For 1995 and later Ford Ranger models, remove the instrument panel to access the heater core chamber. Separate the heater core from the chamber by pulling back and down and remove it from the assembly.
Installation of the heater core is the reverse of removal. Once the heater core is installed, refill the cooling system with coolant. Run the motor to check for leaks and test the heater.