Rebuilding AC system on 1986 F250

[david85]

This could be a long read but it will have plenty of photos for those who want to skim.

Some back ground:

Back when I first got my IDI, it wasn't rare, pretty nor special, so when the factory AC couldn't be revived, I hacked in an FS10 compressor from a later model truck. It was cheap 2nd hand and I had time to make the brackets and weld the pulley on as shown here:

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When combined with Duracool, and later Red Tek refrigerant it worked pretty good for many years but eventually failed again.

Now that the "Tin Bashing" thread is just about complete, I'm coming full circle on some of the things that I wasn't able to fix properly way back when. Due to the amazing summer we've been having up here on the BC south coast, working AC is pretty high on the list.

So now comes the task of putting back the original setup with the correct FS6 compressor. Only problem is I scrapped the brackets when I did the FS10 mod. Like I said, the truck wasn't special back then...at least I didn't think so and certainly none of the local wreckers do either. Even 7.3 strokers are getting rare.

So next place was Ebay. Yup, found two listings.

1st listing: Had the exact bracket I needed for $100USD + shipping. That's a bit steep.

2nd listing: Had ALL the AC Compressor Brackets for $75USD. Reasonable, but the seller refuses to ship to Canada.

After looking at the two listings I decide to steal their photos. Why, you ask? Because I have access to a CNC and I feel like being stubborn. So here's what I ended up with:

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Since the bracket is small enough to barely fit on a 8.5 x 11 sheet of paper, making some test templates was easy. 2nd try gave me a pattern that matched the compressor mounts perfectly.

Next came a metal template on the CNC, which was cut from 1/16" aluminum sheet. One slight adjustment to one of the holes and its good to go. Out comes the 1/2" aluminum plate:

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[david85]

Once cut out, the parts cleaned up nicely. The 3/8" holes needed no adjustment, but the M10 holes did have to be opened a bit. No big loss and since this was my first attempt at running the machine myself (under supervision), I'm happy.

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Mounting the compressor took a little longer than I hoped but it seems to be right where it needs to be. I wasted most of the time scrounging for rusty old bolts just so I could mount it. I'll probably get some new bolts later when the shops open. Seems a bit like lipstick on a pig considering how dingy the engine looks compared to the rest of the restored truck but hey, its still a truck at the end of the day.

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Next update should be when the old hoses, Evap Core, Drier, and Condensor are removed. All in all, a bit spendy, but I wanted to try and get it right this time. Hopefully I have all the parts. Stay tuned...

 

[jwalterus]

Due to the amazing summer we've been having up here on the BC south coast, working AC is pretty high on the list.

Wuss


The only good thing about the drought we've been having here is the humidity is staying down around 50%.
What's the cost on parts for your full system rebuild?

 

[david85]

Wuss

Actually I wasn't complaining. I really do like the hotter weather, even if some are crying about globull warming again (still?). Its been an awesome summer and I'm trying to enjoy as much of it as I can. I'm still hoping to roadtrip either this truck, or my E24 before September. I still need to get the white bar redone on the truck before I can finish the trim, badges, etc.

The only good thing about the drought we've been having here is the humidity is staying down around 50%.
What's the cost on parts for your full system rebuild?

Yup, humidity has been pretty good here too but its going up later this week.

I'm in the hole for just north of $700CAD so far (includes shipping). Everything was bought new from Rockauto though, including the FS6 compressor. After reading up on how poor most reconditioned units were I decided to go all in with only new parts. I was pleasantly surprised to see that all the hoses along with newer style cross flow condensers were readily available for this truck. Hopefully they all fit.

 

[david85]

That went much faster then I expected. New condenser, drier, and evap core with new orifice are all installed.

So far the fit and quality look decent compared to the original parts. Condenser looks good and fit without any drama. Removal and install was pretty easy too. All I had to do was undo the rad bolts and tilt it back toward the engine and it slipped right out.

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[david85]

Evap core was very close to OEM. Only difference I could see was the main inlet and outlet tubes being soldered instead of welded, and the lack of a banding strip across the top & bottom.

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This was the part I thought would put up a fight but it went pretty easy. As with the condenser, I did have to swap over a support bracket for one of the main tubes.

 

[david85]

Called it a night at this point. Still have to put the manifolds for the compressor back on (took them off in order to use the shipping plugs to keep it clean). One of the disconnect valves for the old condenser will need some cleaning as well.

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As a side note, the drier I'm using came with the compressor as part of a kit. It seems to already contain some oil inside. Hoses, evap and condenser were purchased separately but all seem to be clean and decent quality. All the hoses came with a spare set of seals and every end was tightly capped to keep crud out.

 

[david85]

So far so good. Vacuumed for 45 min and charged with 18oz of RedTek. If the gauge on my hand pump is to be believed, the venturi vacuum was at 25"Hg. I wasn't too sure on the oil charge but based on 3oz in the compressor and another 2 possibly in the drier, I added 4 for a total of 9 which should put me in the ballpark.

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The truck was idling a bit low at 600 RPM, and bumping it to 700 RPM made a noticeable difference when parked. I'll have to shoot it with my IR thermometer later (when I find batteries) but a quick drive around down in 30C weather returned numb fingers from the driver's side vents. I wonder how cold it would get on the highway.

The new compressor is also nearly silent. Even when I had my earplugs removed I couldn't hear it turning. Clutch clearance is also very tight, so there is no audible snap when turned on. The only way to know its running is either looking at pressures or at the pulley itself.

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My only real complaint so far was with the flimsy brackets on the condenser for the inlet and outlet lines. The OEM condenser had brackets that were stronger and much better thought out. I'll probably have to add a little something on the new condenser lines just to be on the safe side.

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For now I'll be hanging on to the old parts just in case something catastrophic happens. The only concern left is how well it cools at standstill. It seems ok, but nothing compared to when moving. But that seems to be the norm with these systems.

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[chris142]

What year truck did you order the 6mm condenser for?

 

[79jasper]

The only concern left is how well it cools at standstill. It seems ok, but nothing compared to when moving. But that seems to be the norm with these systems.

I think that's about any system that runs a mechanical fan. Lol
Also the newer systems that run the refrigerant control valve work well at lower rpms. Basically the compressor is always turning, and there's a variable orifice valve that controls hi/low pressure.

What is your idle set at?


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[david85]

What year truck did you order the 6mm condenser for?

I searched everything based on my exact make & model on Rockauto.com. The 6mm cross flow shows up as one of the options for 1986 F250 2wd with 6.9 diesel.

I think that's about any system that runs a mechanical fan. Lol
Also the newer systems that run the refrigerant control valve work well at lower rpms. Basically the compressor is always turning, and there's a variable orifice valve that controls hi/low pressure.

That sounds even more expensive than what I just did. No thanks lol.

What is your idle set at?

700 RPM

 

[david85]

I'm getting more confident now. Outside temperature was only 71F by the time I got my IR thermometer working again. Main thing I was wondering about was temperature of the compressor, but it looks like the hot side is only maxing out at 120F after a highway run.

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The photo of the vents might not be accurate though. The 10F number was after about a minute of holding the trigger on and watching the temperature reading gradually drop. Also had to hold it at just the right angle. Later readings from the rest of the vents were in the mid 20s so I might have to scrounge for a good ol' filled thermal thermometer later on.

 

[chris142]

The infrared gun wont work on aluminum or shiney metal. It will read low.

 

[jwalterus]

The infrared gun wont work on aluminum or shiney metal. It will read low.

It'll ballpark it though.

You really need one of these for the vent:
https://www.amazon.com/General-Tools-DCFM8906-Digital-Display/dp/B00275F5EM

 

[snicklas]

I think that's about any system that runs a mechanical fan.

I've also seen systems with a mechanical fan also use a small electric pusher fan down low on the bottom of the cooling stack. I had a 2000 Dodge Durango 5.9 V8. It had this setup and the A/C would freeze you out at an idle. Plus it was a nice booster for the mechanical fan at low speeds.