Don't go taking screws and plugs out of a charged system on my say so; do some research on this.

A York is a piston pump, to my understanding, and behaves the same as any engine that has a crank-shaft and pistons.

As I think upon it, I don't think a York can have a shaft seal leak like the FS6 and other vane-type compressors as the shaft is not in the refrigerant part of the system --- BUT, don't take this for gospel --- check it out.

The oil pre-charge you mention is in the refrigerant side of the system and is an entirely different animal than the crank-shaft oil; so many discussions get this wrong and when you say "oil" they instantly start going on about Ester and PAG when a York has a separate oil reservoir that has nothing to do with the refrigerant.

A YORK being used on a vehicle A/C system is way overkill for the task; I see the same size York that you have on your truck being used on refrigerated trucks and trailers.

Before you go to removing screws and plugs, read up on this and find yourself an old experienced refrigerant man and see what he has to say about it; of course, you may have to have this discussion with a Quija Board.

Find yourself a York at a swap meet or at the junk yard and check it out on the bench; take it apart and see what is inside; then, put it back together and run it for another million miles.

Unless something is drastically different about your York, I don't think refrigerant can get to the crank-shaft seal; but then, I could be wrong so don't do anything on my say so.

 

A york compressor is just like any other conventional air compressor, with a crankcase, a crankshaft and a piston going up and down. While the crankcase and the top of the compressor are separate, I would still use the proper compatible oil in the york crankcase. Besides the rings, there is nothing to keep the oil out of the refrigerant, and the refrigerant out of the oil.

The york works, but it is big and heavy and hard to fit in the engine compartments as the hoods got lower and lower. Of course we have plenty of room under the hood of these trucks, but all other Ford cars and trucks didn't.

The fs6 is a wobble plate compressor. It has a bunch of smaller pistons arranged much like a gatlin gun. On one side of these pistons are the head with the reed valves like any other compressor. On the back side of the pistons is a wobble plate arrangement, that sequentially pushes on each piston as it goes around. More efficient compact design.

 

I was getting cold on consecutive days then went to work on the blend door, and never started/tested for 3 days. Today after the blend door fix, I fired it up (see other thread—blend door is FIXED!)

Anyway, the pump cycles on and off not quick but regularly and we are back to it not getting cold. ALSO, I would say the HF sniffer is a complete bust—it is not reliable. So, I will be taking it back. I will use dye for any further diagnosis. I certainly seem to have a leak.

 

This is not recommended, but I have done it several times with no harm done. I have heard of a couple other guys on different boards doing it also. When I have a leak and am trying to hunt it down, I use shop air on the system. Refrigerant is just getting too expensive to use for troubleshooting and our tree hugger friends should appreciate us not using it to find a leak. I had one of those old refrigerant charge cans laying around empty that had the gauge and the r134a quick attach fitting already made onto it. I cut the hose close to the can and used a hose barb and hose clamp and mated it to a air fitting that plugs into my shop air. My shop compressor runs about 130 psi, perfect for pumping up the system.

I can then use soap or whatever to try and find the leak. I do not see why you couldn't use dye also, but I am thinking that is not going to work unless you fire the compressor up to distribute the dye through the system. That is one thing I have never done, is run the compressor on just air. The compressor should live with that, all it needs it oil that should be already in it, but I have never had to run the compressor an would be a little afraid to do it.

After I find the leak, I let the air out and put the vacuum pump on it and let it run overnight, just to make sure to boil out all the moisture in the system. It seems to work, I have done it to my wife's car twice now and it works great. She had a hole in the condenser the first time, and several years later a o-ring to the condenser when bad.

 

This is defintely a connumdrum. I have shot soapy water on all the lines, etc, and not found anything when you suggested that a while back. Now I could just be blind of course. OR it really is coming from the pump shaft which would be difficult to spot anyway. I like the vac pump/dye idea though. We shall see. I am not in a hurry at this point. I am just happy to have my defrost back for winter. BUT this bugs me, and when I am bugged, I have to know why.

 

You have filled it several times and have been running it. You should have some dampness (oil) somewhere and dirt has started to stick to it. If it looks oily at all around the back of the clutch, I think the seal is going to be your leak if you see no dampness anywhere else.

 

After I put a tire valve in an empty r134a can and put untelling how many gallons of ultra-humid Kentucky air in my system, in conversation, I found that all the knowledgeable A/C guys in my area have been doing it for years; but, just hint at putting shop air in one on most of these forums and be prepared for the safety police and doomsday speakers.

That being said, I absolutely wasted three long days taking most of my truck apart and laying the shop air to it and wore my hand muscles out pumping my bottle of "LEAK FINDER" - that's what it says right on the bottle in big black Magic Marker, right over where it says Formula 409.

I never did find any hint of a leak and I could charge it to way over 100-psi with shop air and just watch the needle fall.

I would have thought that leaking that furiously, if it were the compressor shaft seal, pouring half-a-bottle of Dawn Ultra Platinum Little Baby Duck Formula in between the compressor and clutch would have it foaming like a mad dog, but nary a speck of any indication of a leak.

Some soul here suggested I look at the bottom side of the hood right above the compressor; and, sure enough, there it was, a big long oily streak exactly above the space between the compressor and clutch.

I put a brand-shiny-new compressor on there and it hasn't lost nary a drop since.


It took me many more days to put everything back on there that I took apart needlessly than it did to actually fix the problem.

Now, this is just my own opinion and may not be anyone else's; no matter how old the truck, it is highly doubtful that you are going to find a leaking evaporator.

Unless you follow dump trucks coming out of the quarry much too closely with #57 Limestone bouncing off the blacktop and through your grill, it is highly doubtful that a condenser will ever develop a leak.

O-ring seals at hose connections = if they didn't leak two days after put together, they are not going to start leaking forty years later.

My 1985 truck still has every hose that Ford Motor Company put on there in 1985 and none of them leak yet.

So....., all that being said, if you all of a sudden have a massive refrigerant leak that isn't easily obvious without even trying to find the leak, just put a new compressor on it before trying anything else --- that's what I am going to do from now on.

 

Our FS-6 compressors have this little piece of felt like material sticking out at five o clock. If you get a seal leak it will become saturated with oil and eventually drip. Badly leaking it'll fling oil all directions, easily seen as a dirty stripe on the underside of the hood.


The York, I believe, has a similar material under the clutch mounting plate only it completely surrounds the seal. It too will become saturated with oil. Unless that material is bone dry, you have seal leak.

If this is indeed where your leak is, I can see why it would be hard to detect with soapy water.

 

Agree, leave the cheap soap at the Dollar General. Seconded opinion from someone who has tested thousands of piping systems over a forty year career.

 

You have shown me something that I was previously unaware of --- thanks.

 

I grew up in the tire business; funny thing is, Dawn is about useless for finding extremely slow leaks in tires, tubes, and such; whereas, the cheapest of the cheap Dollar Store stuff will be foaming like a mad dog.

Now, not to take any credit for using the best choice stuff on my A/C system, I was using Dawn because that was what the wife had sitting beside the sink; if she had of had Palmolive, then that would have been what I used.

 

True, the compressor can usually be a common source for a leak. But always keep an open mind on these things and go in troubleshooting like always. I HAVE found something has struck the condenser and put a hole in it. And I HAVE had a o-ring go bad. I have had hoses go bad, they look like they have some sort of disease and are weeping right out of the rubber. I have had the seals go bad on the fittings where it mates to the compressor. Very often I have had something go wrong at the schrader valve area.

On my 89 I got the A/C system going, it had a very slow leak, but it would last through the season. Most likely the compressor seal. But I would get it going, the next day it was out of gas. It took a long time for me to figure out when I put the cap on the test port schrader valve, the plastic cap was pushing just a little bit on the center of the schrader and letting the gas out. I put a rubber cap on it, problem solved.

 

My 1986 truck with the completely rebuilt, converted to 134a system has needed a small dose of refrigerant each summer since I did the work in 2021. Finally, perhaps I have located the nuisance leak(s) Both of the conversion adapters leak where they are screwed onto the original style Schrader valves. Cheap adapters from O'Reilly's.

Upside is the new self sealing refrigerant cans. The can I used last summer still had all the remaining refrigerant in it. One can per two years doesn't warrant a repair of the adapters.

 

With these adapters, don't you still have the factory Schrader valve inside the original R12 fittings? IIRC, the adapter has a flexible little finger that actuates the original Schrader valve. Your R134a charging manifold presses on this finger, which in turn actuates the original valve. If this finger was keeping slight pressure on the valve, that would cause a slow leak. In theory, you can unscrew the adapter and nothing will leak out.

I had some trouble with an R134a adapter on my truck. It wasn't causing a leak, but my R134a charging manifold set would not reliably open the original valve. I replaced the adapter with a better brand (Sorry, I don't remember which brand) and all was good. Swapping the adapter was a piece of cake, with zero refrigerant escape.

It would be a different story if the original valve has been removed and the adapter now contains the valve.

 

You likely are right about the Schrader valves. Since I can't remember I chose to leave it alone since it only cost 1/2 a can per season. My logic, flawed perhaps, is that refrigerant is getting into the space between original and new. Either because the original valves are leaking past the installed valve cores or they have been removed. Afraid to even partially unscrew and risk blowing out an o-ring and losing a charge. If it ain't (too) broke, don't fix it. At any rate, these are what I got at O'Reilly's

And you are correct about the add on valves. They are equipped to actuate the underlying valve. I verified by looking at the one left in the packet depicted above.
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EDIT: @kr98664 Took another photo of one of the leaks to show what a tiny leak looks like over time. Looking close at the pic I noticed that refrigerant (and oil) appear to be leaking from under the cap as well.


I heard the built up pressure under the cap escape as I unscrewed it. Checked the valve core for snugness and that checked out. So, leaking past new adapter valve core as well as old valve core, if present.