I need to replace my heater core on my 1973 F100. Problem is every reference I have found shows the heater box in the engine compartment while mine is under the dash. The truck has what I guess is the dealer installed AC. I have bypassed the heater core for now. How do I access it? the box appears to be riveted. Do I need to take the dash out? Any help is greatly appreciated. Pictures link below.

Pictures by subscribeman - Photobucket



Thanks!
Ant

 

There are several other posts outlining this, but for the moment since I am unable to look around much. You will need to remove the heater box from the inside of your truck. There are three? or four? nuts to be removed from the engine compartment side of the firewall. two of them are holding the fan assembly in place.
My truck had one other, which was inside the cab near the opposite end of the heater box body, just above the floor vent diffuser (the darker black unit at the far left edge of your photo #2).
The intake duct from the PS edge does not need to be removed, but the duct for the defrost does (two screws on mine, but It looked like originally they just popped off.
Now the fun part, pulling the unit out from underneath the dash!!! its a fight, and you'll be standing on your head in the passenger side floorboard to do it, but it will come out.
Once its out there are four small metal screws holding the rear plate onto the box. Through the plate run the two heater lines, Ta-da
On a side note all the foam (damp, gummy, decaying etc.), is important! keep it or replace it. There was just a wonderful post on this stuff, and the difference in my truck is INSANE just because of that article and new foam!
Now re-install in reverse, which, in my opinion, is worse than demo any day of the week.

 

All the posts I had found showed the heater box in the engine compartment and said it was for 73-79. Is the difference the dealer installed ac versus factory? This sounds a bit easier than those instructions. I'll give it a go.

 

Sorry for being such a noob but I have a follow up.

I think this is a dealer ac unit? Based on the in dash placement?
IMG_5264.jpg picture by subscribeman - Photobucket

Looks like it's going to be a bit more work than I had hoped. It looks like I will have to remove the ac blower
looing up under dash passenger side picture by subscribeman - Photobucket

and a piece of ac duct to create enough clearance for the heater box/blower/core to be removed.
http://s950.photobucket.com/albums/ad347/subscribeman/?action=view&current=IMG_5263.jpg

is this correct? Any insight or tips on how to remove these items?

 

Yeeeah, Uuummm. I gotst No ideas there! I've never had AC in any of my trucks....... Sorry

 

Bump.

It's cooling off in STL so I guess I got to bite the bullet. Any advice about removing heater box with a/c like in pictures?

 

Do yourself a favor and blow the heater core out before cutting the box loose. That way you won't end up with a quart of antifreeze all over your floor when you are wrestling the heater box out from under the dash.

 

hey, onestr8 i have the same set up as you, i was wanting to swap my heater core and saw you were doing it a year or so ago. I was wondering before i get started if you could give me any suggestions or advice on what you did... thanks

 

I think your best bet would be to pull the front of the dash. It's not too difficult. I pulled the dash because I needed the interior stripped. Regardless, the dash would have to come off on mine anyway because of the aftermarket AC unit


Jameson

 

Your truck has Economy dealer A/C that's not combined with the heater. Panel to the left of the glovebox with two A/C switches & registers is the dead bang give-away.

Factory A/C is combined with the heater, has the huge heater box in the engine compartment. The A/C controls are located in the same panel as the heater controls.

There's another type of dealer A/C, but it's totally different, so it's not relevant to this thread.

 

Yours has a dealer AC unit, these are very difficult, my brother and I did one in his 78 and it took a long time and in the end we didn't reinstall the AC unit, they are a real bad unit. I don't have much advice other than start taking it apart and hope for the best, I hope you have a big box of tools and a lot of patience, because there is no procedure that I have found yet for this. All books have said that it is beyond the scope of most mechanics, don't get discouraged, I will look in my chilton books tonight and post what I can find, good luck.

 

I know this is an older post but hopefully a few people are still watching it. I have a 77 f100 with dealer installed air. PO removed all of the underwood a/c parts. I don't drive the truck in the winter however in the past three years of ownership the heat does not work. Like I said u don't drive it in the winter and it has never leaked so maitivation to fix it hasn't been high. But the mornings are cold and not having heat really limits my autumn fun. Any thoughts out there as to why I wouldn't have heat. Did the PO forget to re route hoses or something when they removed the compressor, etc. Any feedback would be helpful.

 

With just heat from the factory, there's no shut off valve in the heater hose (there is one with factory A/C).
The first thing I would do is make sure the heater hoses are connected and the blower motor is working. Maybe the heater core was leaking and the PO bypassed the heater.
If that checks out, then make sure the cable that controls the temp is also working and not stuck in the cool position.
Make sure the mode switch also works and air comes out at the floor level and you're not stuck in the defrost mode with heat coming out at the base of the windshield.
Last, if everything else checks out, the heater core may be plugged and needs to either be flushed or replaced.