I have a 1977 F-250 CS with the 400, AT with no A/C. How do I access and replace the heater core? I am assuming that it is behind the plastic cover under the dash, but it appears that the bottom of the plastic cover is riveted together, Do I have to remove the dash? If so, how? Thanks in advance!!!

 

Well you dont have to remove the dash but you will need to loosen the lower side bolts for the dash and remove the heater box that holds the heater core. The bolts for the dash are on the lower corners of the dash where the dash meets the kick panels. Good luck its not to bad but frustrating.

 

Just did my 77 F250 4x4 400/NP435/ with AC,, not too bad,,, wasn't looking forward to it, but turned out not so bad. So without AC I think it is even easier!

 

How does the box that holds the heater core get removed?

 

Just did my 79 f150. Remove three nuts in the engine compartment, two above and below the blower and one the same size right in the middle of the firewall. Unhook wires on the blower. Unhook old coolant lines. Under the dash remove the cables that come from the heater controller. Unplug the resistor plug on the metal plate. Shimmy the whole plenum out of the truck. The heater core cover will be obvious. Bring it to the store, I received the wrong one my first try.

 

^ what he said. Also helpful to remove glove box door and liner. Luckily you dont have factory air.

 

Does it have the deluxe heater option? If so then it is more like the factory ac trucks. This is easy to tell, does it have vents in the dash? If no vents, then standard heater. Some had a HO heater. This was different as well, procedure similar, but not the same parts. Verify which system your truck has before heeding advice on how to tackle. Usually don't unhook lines, cut them. It saves a lot of wrestling and time. On your way back in be careful. It is difficult to properly align the heater core tubes with the holes in the firewall, and when going in, those pipes wedge into the firewall and bend and rupture the solder, then the new one leaks. A good idea is to put a cover of some sort over the pipes, to keep them from dragging on the insulation. Good luck.

 

The core is sealed around the edges with foam. The original foam is probably dust. I used some self stick foam strip from ACE - 1/4" x 1" from memory - to replace.

 

There are a couple good posts on this, here is one.

https://www.ford-trucks.com/forums/4...-question.html

I have been putting off changing my whole box, given old one was pulled n never replaced.

Wish thre was a better sticky on these

 

Anouther link

https://www.ford-trucks.com/forums/1...g-air-box.html