Heater Core Replacement

The heater core in the Bronco is fairly easy to replace. I did this hoping to get a little better heat in case there was a bunch of crap in my original heater core. The core is pretty cheap...only about $20.

Start by draining the radiator so you won't get coolant pouring out when you disconnect the heater hoses. Remove the hoses from the ends of the heater core that stick thru the firewall into the engine compartment. Remove the foam around these tubes. It will probably be brittle so be careful if you want to reuse it. Next remove the 4 nuts around the hoses. Your heater box should now be loose.

Next remove the air duct going to the air inlet box on the passenger floor board. There is a clamp holding the hose on that you should undo to get it loose.

Now you can pull on the heater box loose from the firewall. This will help you get to the rest of what you need to disconnect. The firewall insulation will probably stick to the heater box. Reach behind it and pull it loose so you don't rip it apart when you pull out the heater box.

Undo the clamps and disconnect the hoses going to the defrost ducts. Careful, they could be brittle.

Disconnect the cables going to the defrost controls and the heat control.


Disconnect the wiring to the blower motor. There's 2 connections to a resistor that controls the motor speed, and the positive wire to the motor.

The heater box should be free to come out. Take it out of the Bronco to someplace you can work on it.

Remove the screws on the end of the heater box that hold on the hose to the intake. You should now be able to see the heater core.

Remove the rest of the screws that hold on the panel on the back of the heater box. Take the panel off. You can now take off the clip and pull out the heater core. There is foam all around the heater core that is probably brittle. Be careful with it so you can reuse it.


Replace the core with the new one, then reverse these steps to reassemble it.


Page by Marc Reiter - last modified 01/22/02
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