Driving my '78 in the winters here in the Treasure Valley of Oregon and Idaho means the temperatures can range from highs of 50*F to lows in the negative teens. Add on top of that a weather phenomenon known as an inversion and we can get stuck in a freezing fog for weeks at a time. I quickly found that my heater was completely inadequate to keep up with the fog freezing on the windshield on my way to work. I also had to bundle up in insulated overalls and layers to keep warm. The nail in the coffin for my heater was the slight cloud that it started putting up on the windshield during defrost. Since the vent door on the passenger side was broken I decided I would go looking for another heater box. I was lucky enough to find that a fresh '78 Bronco had come into one of the semi-local pick-a-parts. I pulled the whole box, the vent door and the foot panel that was apparently missing from my pickup. I can report now after two weeks of driving during the dropping temperatures that I won't need to bundle up to go to work. We haven't had an inversion yet, thankfully, so I can't report on that yet.

Here is a comparison of the Bronco or High Output heater core size:


I had noticed when driving a rattle of leaves in the ductwork. I have read of several members finding that turning on their blower motor results in smoke and sometimes fire. To prevent this from ever being a problem I went down to the local hardware store and purchased some aluminum screen. I trimmed a small piece to fit the inlet for the fresh air vent and epoxyed it into place.


I plan on adding a screen to the drivers side vent as well. If any of you have to live with Elm trees you will understand the headache of the seeds getting into everything and blowing into your vehicle when you open the vents.

I don't know that either of these ideas are original. In fact I know the High Output heater was an option and have seen one pickup that had been so equipped, but I thought I would put this out here for anyone else who may need them.

 

Wish I had known about the high output core when I replaced mine several years ago. I just checked O'Reilly's and the HO core is $5 cheaper than the standard one, so maybe I got lucky; but I don't remember any difference in size.


My 77 originally came from SoCal so I seriously doubt it had a h. o. heater stock. Plus I'm not driving it right now anyway, but it is something to look for when I get around to restoring it.


Robert

 

Had heard that the HO heat was standard in the crew cabs and that's what I took mine out of. Can anyone confirm this to be true?

 

Hi neighbor , i say neighbor because I live just across the river from you in Parma Idaho. I wonder if somebody put the wrong core in your heater at some earlier time it's small compared to the one you put in. I put a used mustang core in my old 64 falcon once and it fit about that bad and never put out much heat at all. My 73 standard short box F-100 has a large core like that , it is heat only no a.c . JIM

 

My brothers '79 F150 also had the small heater core. If you look at the pic comparing the sizes you will see on the small one there is plastic along the bottom preventing the use of the large core without modification to the box, which my brother did. He has found that his modification did not work as well as he would have liked and can't quite shut it fully off.

I bought my Camper Special F350 out of Notus.

 

Good idea of the screen there, I removed mine years ago and installed one

 

Been to that little town a lot, went to junior high there a long long long time ago. Not much left of it now as for stores like most small towns. Does have new high school since i went there and getting ready to replace the old grade school building. Good muffler shop there ,had duals put on my 73 , did a great job.