How to Change a Heater Core in a 94 Chevy Truckby Daniel Valladares; Updated November 07, 2017
Items you will need
Replacement heater core
The heater core on your 1994 Chevrolet truck heats up the air before it is pumped out into the vehicle's interior. A faulty heater core will prevent warm air from being circulated and may even leak coolant out onto the passenger's side of the vehicle. Replacing the heater core on your 1994 Chevrolet truck is a straightforward assignment, but it is also very involved. You can expect to spend well over an hour just on removing the old heater core from the vehicle.
Turn off the truck and use a socket wrench to disconnect the negative battery cable.
Place a drain pan under the radiator and loosen the radiator drain plug with a socket wrench to drain the vehicle's cooling system.
Remove the glove compartment by removing its securing bolt on the inside with a socket wrench. Remove the lower knee bolster by removing its three securing screws with a Philips screwdriver and prying off the panel with a slotted screwdriver. Disconnect the three electrical connections underneath the panel.
Remove the center air distribution duct from the floor of the vehicle below the dashboard.
Use a slotted screwdriver to pry off the hinge pillar trim panels. Remove the blower motor cover and then remove the two screws securing the motor. Pull the motor out of the vehicle.
Remove the two screws from the rear of the steering wheel to remove the steering wheel cover. Remove the single bolt securing the steering wheel to the steering column with a socket wrench. Disconnect the electrical connections in the steering wheel and pull it off of the column.
Remove the coolant overflow tank by pulling it out of the engine compartment. Disconnect the heater hoses at the heater core's connections.
Remove the four attaching screws and the nut and then remove the heater case. Remove the seven screws and lift off the heater case cover. At this point, you can remove the bolts securing the heater core to the truck and pull the heater core out of the vehicle. Place the new heater core into the vehicle and reverse the removal process to install it. Do not forget to tighten the radiator drain plug and to add coolant to the radiator until it reaches the "Max" line. Reconnect the negative battery cable.
Wear gloves when replacing the heater core on any vehicle.
Be careful when removing the heater core as coolant may still leak out of it.