Thinking about putting in an A/C system in my 85 4.9L F150. It is a non-A/C truck. Anyone done this before? Pitfalls? Thanks again.

 

The biggest one is the firewall as they are not the same between the A/C and non-A/C trucks. You would be best off looking for an aftermarket kit But that has not stopped people from swapping firewalls. Pretty sure Dave will chime in as he did this swap and is the resident expert in doing it..

 

Yeppers, I expect the same.

Paging @FuzzFace2 please pick up a white courtesy phone

 

 

As said the firewalls are different and its not so easy to swap them with out having a truck with AC to get it from along with all the other needed parts.
Then you need all the tools needed to remove both firewalls and install the AC one back in.
2 hole non-AC firewall

3 hole AC firewall to be grafted in to the non-AC cab.

AC firewall placed over the non-AC firewall

non-AC firewall cut out

Starting to weld into place

Welded in place

Painted with masking still in place

HVAC box in place

If I was to do this again I would not swap the firewalls but make a pattern of the 3 hole AC wall and transfer it and cut the 3rd hole and some smaller holes as needed.
You will still need a complete truck for ALL THE AC PARTS both under the hood and the full dash as it has the vents and controls.

You do not need the full wiring harness across the top of the dash into the engine bay as the AC harness it a plug in to a normal harness so you will need that from the AC truck with the full dash.

This next part you would need to do even if you went with an aftermarket AC kit.
Being you have a truck with a 300 six I think one of the hard parts to track down will be the motor brackets for the AC compressor, pulleys (think its just the water pump one you will need).
But the larger radiator with shroud I dont think will fit your radiator support as the AC one is larger than non-AC and is the opening in the support.

So as you can see it is not and easy job adding AC to anon-AC truck
Dave ----

 

I would probably go with an aftermarket kit or hunt down dealer A/C from a junkyard.

 

I believe they would be under dash units and there is not a lot of room in the cab to start with.

But again depending on what motor you have could make or break this up grade and the 300 six compressor brackets & pulleys can be hard to come by.
For the HVAC box & dash vents I would try and find / buy all the factory parts or truck for them.
Dave ----

 

For the A/C brackets, I would also consider later EFI applications as A/C was much more common on the later trucks with EFI this would also allow you it ditch the V belts and run a serpentine system.

 

Welp….. you’ve given me much to chew on fellas, I thank you for your knowledge and insights. My only issue with aftermarket is the ugly below dash unit and that’s what directed my thoughts toward OEM A/C unit. Yep, too much involved for an OEM swap so I’ll have to backup and punt on that idea. As always I’m grateful for you guys!

 

If you can find everything in the junk yard like I said just make a pattern of the 3 hole firewall and transfer it to your truck.

You have the 1 large hole to cut out that you can see here.
At the top a oblong hole just above the large hole and part of the oblong is over a round hole.
Then 3 holes at the bottom below the large hole.
1 is already there (the largest) 1 right below the large opening - think for the HVAC box bolt?
And 1 just left of the 1 already there.
On the inside there maybe a HVAC box bolt hole from the non-AC box but thing it may get covered with the AC box?

Now another way to go with the aftermarket AC is to only get the compressor / brackets / hoses and maybe the control and hook it up to the factory AC dash part.
Or get the aftermarket setup and just the AC dash vent part and hook the air vents of the aftermarket to the AC vents.
This way inside will look factory dash other than the control.
Its still work to do but is an option.
Dave ----

 

If you are persistent you should be able to locate the parts necessary for original dealer-A/C which was meant for non-A/C trucks.

all you really need if the under dash stuff(evap, controls and ducts)
the under hood stuff can be new or taken from factory A/C trucks.

 

I believe I’m going to use an aftermarket kit (Vintagair) and try to get and use the factory plenum and vents to fit to the aftermarket box.
Kind of a hybrid. I can buy the Gen II mini mock-up unit under $50 and with the dash pad off see if it has the space and if the OEM plenum & vents (dash & defrost)
can be used.

 

Keep us posted with pictures as I am sure it will help others that was AC in a non-AC truck.
Dave ----

 

Yes I will. Why keep the info to myself?

 

It will take more effort and interruption to your work than you realize to post back, especially if you take pictures during the construction. And then keep track of all the part numbers and stuff you used to do it. We appreciate any effort you make to educate us on what it takes to make the conversion. The dealer systems are no longer available and many of the parts are hard to get.