Heater Core Removal & Re-installation: A Short Guide to Repairing Your Automotive Heating System

Sooner or later if you keep your vehicle...you are going to have to replace the heater core. This a no fun proposition anyway you approach it. I have the misfortune to own a vehicle that places the heater core under the dashboard. And it is placed in such a manner that you must completely remove the dashboard in order to change out that heater core.

There is no way I would undertake such a repair job without complete factory instructions. I lucked out finding those instructions on line and down loaded them and printed them out. All twenty one pages of them.

This particular vehicle is an F-150 pick-up truck. And while nearly all heater cores are indeed under the dash, on this Ford..it is not only under the dash but it is enclosed within a sealed compartment and it is a requirement that you remove the dashbord almost completely in order to lift the lid off of this compartment and remove and then replace the core. A daunting job which took me about 10 hours start to finish.

The first order of business was to disconnect the battery terminals. This is done for a couple of reasons. First and foremost...one of the requirements of this job is to remove one of the air bag modules. You do NOT want any power remaining in the electrical system if you are going to handle one of these hybrid bombs. If it should deploy while you have your face mere inches from it, the deployment could do you very serious injury. There are chemical catalysts at work to generate the gases needed to deploy the bag. So disarm the system by removing the battery terminals.

The instructions I followed were precise for the vehicle I was working on so I went at the job in a step by step method. After the battery terminals were removed the instructions had me disconnect main electrical terminals, vacuum blocks, radio antenna and as one of the last steps, removing the bolts holding the steering column in place and lowering it to the floor of the vehicle.

The instructions showed exactly where each screw and bolt was located in order to free the dashboard from it's mounts and allow it to be lifted up an away from it's position. I would strongly urge anyone facing such a repair to down load, or purchase instructions for your specific vehicle.

With the help of a neighbor the dashboard was lifted and placed upon the seat and I was able to get to the heater core box. The box contains not only the heater core but a large air conditioning component and the air blending door. The lid is held on with about fifteen screws and once the lid is off I needed to lift the blending door out of it's slot so the heater core could be moved.

Ford and probably other manufacturers now use a quick release/connect device on the water pipes leading to the heater core. This quick connect is comprised of a metal fitting on the end of the hose where it connects to the heater core inlet and outlet tubes. And on that fitting are two o-rings, a synthetic spacer and a plastic shroud like device. The shroud clips over the heat core tubes and the o-rings and the spacer fit over the tube and seal it. In my case I found it easier to simply use a hack saw blade to cut the tubes off of the heater core from inside the cab and then pull the tubes through the firewall from under the hood. Once I had them pulled free it was just a matter of minutes to remove the old dried up and brittle shrouds and o-rings and replace them with new ones from the auto parts store.

With the old leaking core removed and the new core installed with the tubes poking into the engine bay again, I re-installed the blending door and popped the cover back onto the heater core box. With help from the neighbor the dashboard was again lifted onto it's mounting brackets and I went about the job of reinstalling all of the dozens of screws I had taken out. The air bag module was carefully replaced and then all of the vacuum and electrical connectors.

Out under the hood I became a sudden and welcoming fan of the quick connect/disconnect heater hose. You simply push the hose onto the inlet and outlet tubes of the heater core and with a solid and satisfying "click" they are again where they belong.

Now seeing as how one really should drain the cooling system before doing this job it was a good idea to go ahead and replace the old coolant with a fifty/fifty mix of water and antifreeze. A fifty/fifty mix is optimum because pure antifreeze or any other mix ratio will not provide adequate protection.

With everything tightened and with new coolant I felt ready to drive my truck again and enjoy heat in the cab but without the unpleasant odor of antifreeze being emitted from the vents and no sticky vapor adhering to all surfaces and making them damp and sticky. Ten hours of stretching and grunting and only a few scraped knuckles i had saved myself something like 800 to a thousand dollars of labor expenses. The heater core, hose fittings and antifreeze cost be about 80 dollars. A fair trade in today's economy