Good morning all. I have a 1986 F150 XLT Lariat with factory AC. I've dabbled into AC a little but never handled a conversion from R12 to R134a. It seems simple enough to me. Swap the drier, maybe some hoses, fittings and all the o-rings, and flush the system, well as the R12/R134a dont really mesh well.

My main concern is where to find the "retrofit" pieces or parts. I've jumped my low pressure switch and my compressor comes on so I dont think I need a new compressor (yet). Probably looking for the high side line, drier (accumulator) and anything else needed to make the swap. Where do I find these parts? Most of my quick google searches only show me the fitting adapters and stuff.

 

Walmart used to be the best place to get the conversion kit. As long a your hoses are in good shape and there are no leaks, you can use your old hoses and o-rings. The drier is a good thing to change just for insurance. No need to flush the system. The old r12 oil will just lay in the system and not hurt anything. But you will need to get a vacuum pump and evacuate the system. The cheapest place to get the pump is Harbor freight.

Once you get the drier changed and pump down the system for a hour or so, you can check for any obvious leaks by watching the vacuum gauge if you have one. That's another thing you can buy and is nice to have is the gauge set from Harbor Freight also. Once you get a good vacuum with no big leaks, just get a piercing kit for the cheap cans of r134a, and put the can on the gauges. Open the fill valve on the gauges till you hear some air coming out of the fitting on the gauge, and then plug it in and fill the system. You won't be able to get but so much in there till you have to start the engine and then jump the low pressure switch to let the compressor suck the refrigerant in the system.

It can take a long time, if you are impatient like I am, you can turn the can upside down for a second and then right side up. Keep doing this over and over, keeping an eye on the compressor. You don't want to keep the can upside down for a long period, you can get liquid in the compressor and lock it up. Usually two small 12 oz cans will get you going.

 

I have the gauges and a good vacuum pump. I know the secret to a cold AC system is vacuum time and ensuring there are no leaks. As far as I can tell, the system looks complete but the manifold block on the back of the compressor looks like a sensor or something broke off? Anyone have a picture of theirs for me to compare?

 

For what it's worth, new hoses are pretty cheap. Frankly, the whole system is pretty cheap, relatively speaking. I know that it may not be a trivial sum, but I've got less than $500 in a total system replacement on my '85 F250. I replaced every single component on it because I simply didn't want to have to risk having a 35+ year old hose that looked good start leaking 3 months after just replacing the stuff I knew needed to be replaced. Granted, I'm still running it on some leftover R12 from my 30+ year old stash so leak prevention was my utmost concern, but even if I had done the retrofit to R134a I'd have done the same thing.

 

My utterly satisfying and bone-chilling experience with an R134a conversion here:

https://www.ford-trucks.com/forums/1...ce-thread.html


With an R134a conversion, I recommend changing the orifice tube. This thread has the Four Seasons part numbers for the different applications:

https://www.ford-trucks.com/forums/8...a-c-motor.html

I know NAPA has them. That's where i got mine. They can search by the Four Seasons number. I'm sure you could also find them online.

 

No sensor on the compressor in that system. May be part of the high pressure pop-off valve.

 

It sounds like we have basically the same truck as mine is also a 1986 F150 XLT Lariat. All I did to my ac was pull out what little r12 was left in it and added the 134-a. That lasted for about 10+ years or so then I noticed it wasn’t cold just cool so I pulled the orifice tube and cleaned it. I put it back in pulled vacuum on it then recharged it and it’s still blowing cold. I got my high/low fittings at Walmart but not sure if they still have them or not.

 

If your truck's AC compressor has any signs of front desk leakage, replace it.

Changing orifice tube has been mentioned. I did it. Changed from original blue to red. I think I am going to change that back to blue. My AC gets too cold. I think they should make a size in between the two, blue and red.

Low pressure suction hoses from dryer to compressor are becoming scarce. High pressure hose from condenser to evaporator has a "valve" at the condenser. It was an assembly line thing and is not necessary. The o-rings in the valve itself are square profile. I couldn't find any new ones in HNBR. I replaced it by using a standard brass 3/8" pipe coupling. I machined a chamfer on each end to accept a regular o-ring.

In 1987 the F series trucks got away from screw fittings and switched to slip in. If I were to do this job again, I would look into switching out all components for the later style. Those parts are still readily available and cheaper.

Full disclosure: I resealed my old compressor. A job I would caution against. Too many variations of seals and gaskets for the F6 compressor and $$$. I also canged all my other components, hoses, dryer, condenser (serpentine) and evaporator.

 

R134a is cheap enough (well it used to be) that you can fix the obvious things, fill it, and then see what happens afterward. Make sure you get the retro fit kit that has the ester oil and the refrigerant all in one can(s). Once you get the ester oil in it, then you can just buy the plain 134a cans.

 

Yep thats whats on the back.
Note the R12 & 134A low pressure switches work at different PSI.
I bought a 134A switch but I have seen it posted you can adjust the R12 one

When I did my system I bought the HF pump works great and went with and gauge set worked about 4 times and the sight glass leaks and I have it to long to return
I had to replace the condenser, mine had crushed tubes, and hoses because I went with a newer pump , the old one was a York and bdid not have all the brackets for. I also replaced the dryer and valve with a blue one. I have had 1 leak after another because of new O-rings leaking or me forgetting to tighten up on a fitting. I think I have another O-ring leaking but I need to clean the dye off and leak check with a black light to find just what is leaking at the pump the line or the manifold?
Dave ----

 

You would think that the compressor would be rated for a certain pressure, regardless of the type of gas it's running. Afterall, you are trying to protect the compressor and the same lines in the system. In my experience, if things go wrong the pop-off valve will blow (and it's self resetting) and if that doesn't blow the belt starts slipping. Had them totally lock up with the belt slipping. Turned it off, fixed the problem, and the compressor was fine.

 

If you need a minor adjustment to the cooling, you can adjust the low pressure switch. If you unplug the wiring plug there is a small screw in the middle you can tweak.

 

Been there, done that. The AC professional at ackits.com suggested going back to the blue.

 

Some notes from when I converted mine.

The new r134 low pressure switch i purchased had metric threads. So I ended up adjusting the r12 one to work.

The old r12 system doesnt have a high pressure switch the newer r134 setups have them on the pump. If trying to run the newer r134 pump with high pressure switch you will need new hoses that have metric on one end and standard on the other or switch the entire system over. This is what I ran into someone might correct this.

Replace all orings regardless of replacing hoses there is not that many of them and your talking like 12 dollars for an entire set. Plus when flushing i like to section out areas not just flush the entire system at once so I'm opening up fittings anyways. I say this because I missed the one oring that is behind the grill of the truck not knowing it was there and it is the only leak i have had since replacing mine.

Also on The o ring I belive I have heard that the newer refrigerant or oil can escape the older orings. But I'm not sure on that

to end I would flush it all out replace all o rings and drier and new orifice tube regardless of wear and recharge it with Ester oil reusing all old hardware but that's just me

[Edit: the hardest part for me was getting rid of a non leaking system filled with r12 (my pump seized) also I ordered the retro fittings on Amazon for like 8 dollars]

 

GooMeng R-12 to R-134a Retrofit Conversion Adapter Fitting 1/4 SAE Thread,R12 to R134a High/Low AC Fitting

oops sorry just saw these are unavailable now but i would bet amazon has a alternative