Link to the tech article for reference: Clicky Clicky

Ok, I have a '79 F150 with A/C. I'm thinking the heater core is bad because it fogs the windows and smells like antifreeze.

So, I printed a copy of the tech article to bring out to the garage with me, but now I'm lost, and the truck is half way apart. I will quote, then ask my question under it. Below that is some links to pics of my mess, feel free to draw arrows to the parts if you want. My email is mudmachine @ gmail.com


What part is the plenum? And where are the two screws?





Is there 6 screws to remove? The bottom two have the heads rusted off and I can't get a wrench on them, any ideas?





What is the "case"? And does the evaporator come out under the dash or under the hood? Does the outer housing under the hood stay mounted to the firewall?


http://i4.photobucket.com/albums/y11...2-03-05007.jpg

http://i4.photobucket.com/albums/y11...2-03-05006.jpg

http://i4.photobucket.com/albums/y11...2-03-05001.jpg




Sorry for so many questions, and thanks for any help you can give.

 

If you didnt get the tech info from www.autozone.com I would try there.The plenum is the box assembly you see under the hood.

 

No, the plenum is in your second picture. I can't remember why the instructions say to remove it. You can try to skip that step and see if it's necessary.

In step 12, you need to remove the black plate with the wires passing through it. It is on the left side of the evaporator core. I can't remember the number of screws holding the evaporator, but 2 are pictured in your first pic. If they are totally rusted, you might try a vice grip, a needle nose vice grip, or a dremel tool and drill them out.


The 'case' is the housing under the hood. It remains attached to the firewall. The evaporator comes out under the dash.

Good luck. You are on the right track here. Almost this whole job is done under the dash. If you're careful, you won't dump the AC charge and the whole system will stil be operational. You may want to consider changing the blower motor while you're in there. Will save you another trip. Although if you have to go in again, it will be quicker.

BTW, the tech article is from the Ford service manual.

 

You are almost there. The plenum is the thing that is an air duct. Once you get that black piece out of the way, I think you can unhook some of the wires there too. you will see alot more. the evaportor is what you are looking at. make sure the heater hoses are off the core under the hood, pull that evap out and the heater core is held in place by some metal brackets on the edges. unbolt them the top ones are hard to reach. Once thats out the core will come out, I had to push from the outside to get it loose.

 

Ok, finally got it done. Thanks for the tips.

 

Way to go.

 

I forgot to add this earlier, but the plenum needs removed to allow the A/C hoses enough room to move so the coil can be pulled out of the way. I just moved it down and to the side enough to allow clearance for the lines to slide out.