Automotive Air Conditioning Information Forum

1986 F150 AC Restoration

First paragraphs are background. My MO and questions follow in "chapter two".

My 1986 truck, owned since new, had the AC quit about five years ago. Last summer, as an at home project (due to pandemic) I have been completely restoring the vehicle. I'm at the point where all I have left is the AC.

The truck's AC worked great for thirty years with an occasional spritz of R12. Never added that much and not necessarily every year. Over time you could tell where the leaks were. Oil residue around the shaft and on both crimps of the compressor discharge hose.

When I disassembled the system I had used AC flush solvent to clean all the components utilizing one of those cannisters you fill with solvent and power with compressed air. All three hoses (though I was pretty sure the discharge hose would be replaced), the serpentine flow condenser, and the evaporator. The evaporator being parallel flow, I poured solvent into it and did the shake, rattle and roll. Then poured out the solvent. I blew everything out with compressed air and sealed up the ends of everything with plastic and rubber bands. Reinstalled the condenser and evaporator and stored everything else.

When I opened the compressor to survey the possibility of replacing the seal, the compressor showed only trace amounts of oil. Shaft and swash plate bearings bone dry.

So, I had a low mileage FS6 compressor from a 1988 Crown Vic that was very clean and lubricated inside. I decided to use it for the resto.

Chapter two

It has been a trial but I think I have located the parts I need. Shopping for individual parts of a compressor that has one hundred variants is difficult. Got the proper cylinder housing seals and gaskets today. I'm ordering the carbon shaft seal from Tim on Monday along with some other items.

I intend to recharge with R12 as I have thirteen pounds on hand. (truck's original placard calls for 52 oz. of R12.

I plan on using a blue orifice tube because I'm pretty sure that's what I pulled out. Confusion arises because they seem to call for blue with 134a. Can anyone verify what orifice is needed for R12?
Answer: Found original in parts box. It's blue.

I plan to use Ester oil so if my R12 attempt fails, I can easily switch to 134a. Is there a chart somewhere that calls out oil amounts for the original R12 system?
The 1988 FS6 compressor I will use had only a few ounces of oil in it. Any oil in the rest of the components is long washed away.
Answer:Found a chart. 10 oz.

When I reassemble the compressor, I plan to make certain the sealing o-rings are oiled.
Should the carbon shaft seal surface be oiled?
My thought:With no feedback stating otherwise, the carbon sealing surface will be dry. EDIT: Now I'm finding information to the contrary.


When I reinstall all the components, I question whether the service valves on the compressor are necessary or would be better left on the shelf. Since I'm getting new hoses anyway, omitting them would pose no real added expense. The valves I have show no signs of ever leaking. Thoughts?
My thought: I'm using the valves so I can reuse the suction hose. The new discharge hose was less expensive with the valves.

Just for the record you cannot flush a PF condenser

tbirdtbird wrote: ↑Sat Jun 26, 2021 6:10 pm Just for the record you cannot flush a PF condenser

I'll look at the condenser more closely. I certainly appears to be a serpentine flow. No headers on the ends, just a bunch of return bends.

An original 1986 F150 condenser will be a tube & fin unit as you have pictured. They can be flushed.

A serpentine condenser is a flat piece of extrusion with many passages side by side. It is then bent in to repeated flat rows with fins between. Effective as a condenser, but easy to clog and NOT flushable.

You can update an F150 with a more effective parallel flow unit. Ford did so in 1995. But your tube & fin will work ok if it is in good shape.

Question: Where can I find the torque value of the six long, thru bolts that hold the compressor together. They were very tight. I had to turn up the air pressure on my 1/2" drive impact to break a few loose.

Answer: The 8mm bolts on my 1988 FS-6 compressor are T40 torx socket heads with no markings. I find the hex head cap screws on my 1986 FS-6 compressor are marked 10.9. So, 8mm Class 10.9 calls for 41.3 ft/lbs. Generally, a T40 torx head bolt has a torque spec of 54-65 Nm or 40-49 ft/lbs.
EDIT: Now I'm finding a value specific the the Denso P10 (essentially the same compressor) of 27 ft/lbs. *The Ford factory service manual calls for this value with re-used bolts.

Other information:

bohica2xo wrote: ↑Sun Jun 27, 2021 10:39 am
A serpentine condenser is a flat piece of extrusion with many passages side by side. It is then bent in to repeated flat rows with fins between. Effective as a condenser, but easy to clog and NOT flushable.

Thanks for that. My terminology was incorrect.

I had removed a dark blue OEM Ford orifice tube from my truck's AC system. It has a .067" bore. Is the bright, light blue MT0092-1 I bought the same size?

Answer: A fresh start hunting this information came up with .067"

Now that I know exactly what a serpentine condenser is, I have another question. Would it be okay to use a new one on my 1986 truck with a 134a conversion?

The parallel flow condenser (serpentine I guess I had thought that term meant fin and tube as you pictured above)
https://www.google.com/search?q=paralle ... q9a4DuqMVM
(But the mods here are the penultimate resource)
came about because the tube and fin as you show did not work out very well for 134 (and I suspect are more expensive than PF). 134 needs more condensing density

I've been doing more research on this since I posed the question. No definitive conclusion but the sentiment is use parallel flow only with 134a.

I have access to a new (but bent up) serpentine condenser for cheap. No serious damage that couldn't be easily addressed. One bent outlet tube, no kinks. It has an out of square trapezoidal shape that could be tweaked back to rectangular. But it seems I likely have no use for it. I'm going with my OEM tube & fin for the R12 project. If that doesn't work out right off the bat, I'm converting to 134a.