I've read numerous threads re replacing the heater core on an AC-equipped F-Series. I finally figured out how to do it and realized that it was referencing factory-installed AC; which is not what I have. It sounds to me that replacing the heater core in a factory-installed AC truck is cake compared to a dealer-installed vehicle. True?

I have a '78 F-250 and haven't done this project before...obviously. I'm fairly mechanically competent but don't have a clue where to start. Has anyone successfully conquered this formidable foe and lived to tell the tale? If so, where does one begin the project (eg I'm not sure how to get that big black box out of the way, or the cables detached from it)? Here are a few pics of what I'm looking at. I welcome any and all productive feedback.

 

its easier to do on a dealer installed unit than it is to do on a factory installed a/c unit.

 

Please elaborate (preferably with details), because that opinion is contrary to most of what I've read on this forum

 

This thread may help you, and I'm sure you could PM Dak for some pointers on the process.

https://www.ford-trucks.com/forums/1...ne-photos.html

 

jsutton, thank for the link! Looks like he pulled it off. He didn't provide much info on how. Hopefully he'll get back to me...but if he doesn't, does anyone have any info on this? On the link it almost looks like he does most of it through the glove box hole.

76gdmn, you seem to know something about this. Care to back up your statement with some substance and enlighten us?

 

My truck had dealer installed a/c mounted behind the glove box. I took out the glove box liner and the a/c controls. Then had to remove the entire a/c assembly from behind the dash. I didn't loosen the dash at all but it was a very tight fit getting it out.

I then removed the entire heater box assembly to replace the motor/fan and heater core. I also sealed any gaps where there were gaps in the heater box. While I had it all out from under the dash, I used duct tape to make a seal around the defrost duct where it comes up to the dash. Mine had at least a 1/2" gap where the air was just blowing under the dash and not actually making it to the windshield.

When reinstalling I put the heater box back in place and did not reinstall the a/c box. The previous owner had removed the compressor/evaporator etc under the hood so all my a/c really did was blow air. I didn't want to have to put it back behind the dash since I don't use it anyway.

 

Thank you!

So you removed the AC components through the glove box hole?

Can you do this job without disconnecting the AC and losing your freon?

How do you remove the heater box? I'm not sure where to start on that...where the fasteners are and how you do it with the cables attached to it (since you can't remove them while they're under the dash...at least one in the front).

Thank you again for the info/details. I'm sure with a little guidance from the few (few that I've heard of) who have successfully accomplished this I can tackle this.

 

The a/c box itself had to be taken out from underneath the dash. But having access to screws through the glovebox helped it out. And taking out the glovebox liner only takes about 2 minutes.

and as I mentioned, the previous owner had removed the guts under the hood for my a/c system, so I just had lines run through the firewall that were cut.

I would recommend you go buy a Chilton's manual. It tells you step by step how to remove and reinstall the heater box, and shows diagrams where the screws are, and how to disconnect the cables, etc. The manuals are about $25, I got mine from O'Reillys.

Basically to remove it, you have to disconnect the two cables, remove the fresh air vent box (I think its 5 screws) from under the dash, and then there are three bolts in the engine bay (two by the blower motor, and one behind the engine). Remove the nuts from the engine bay and then you can jimmy the heater box out and down from under the dash.

 

Thank you, again! That is helpful.

How did you get to the cable screws to detach the cables from the heater box? I know that at least one of them is just behind the metal dash, facing the metal dash so that you can't get a screwdriver on it.

Sounds like I do need to get a Chilton. I've heard Haynes is usually better. I'll put that on my "to-get" list. I'm thinking that if I can get the heater box out that the rest will make more sense.

 

Hey Wplayer !
I cant help but notice your mentioning how much you've read ! Dont spend too much time in front of the computer thinking about it, get a manual, start "twisting wrenches" , Iv'e been there, the best way to answer these questions you have is to dig in and get these components in front of you in your own hands so you can see for yourself and understand better what needs to be done.
Nothing wrong with seeking answers, the internet is AWESOME and there is no better site than this, but sometimes you just have to JUMP IN a little deeper. And now I welcome comments on how out of line I am !

P.S. I also Hope to be installing A/C next spring and no doubt will probably have a post from Wplayer exactly like this one on my thread !