94 Ford F250 AC system oil?

After a lot of abuse, I finally put my truck in my shop for a lot of work. 1994 Ford F250 4WD turbo-diesel 7.3 IDI (NOT a Powerstroke). No rust, no winters. Had 200,000 miles on it when I got it and now has over 400,000 miles. Engine (IH-Navistar 445 c.i.) still runs like new. A lot of new front steering parts including a new steering box and power-steering pump. New brakes, rotors, calipers, wheel cylinders, master-cylinder, rear axle seals, etc. Put new solenoid-pack in the E40D trans. Lots of parts problems along the way.

So - had it in my shop longer then planned. The closer I looked the more things I was finding wrong. Took it out for a test drive. After I used the brakes four or five times, I lost all power to them like the vacuum-booster went dead. Let it sit for 5 minutes and they worked again. I assume the vacuum-pump is bad. One of the few things I never changed on this truck.

So I ordered a new vacuum-pump from Rock Auto. In the mean time I decide to do something "easy." That is . . some wiring. I want to add a 600 watt DC to AC inverter under the dash. Should be easy, right? I needed to run some 8 gauge wires from the inside of the cab (under the glove compartment) - to the engine compartment. I measured carefuly (I thought) and drilled a hole just above the carpet on the floor. BIG MISTAKE !! Big woosh and oil and AC refrigerant spraying all over the place. I drilled a hole right into the AC evaporator. I still cannot believe I did this.

So, the AC is one of the things on this truck I have never touched. It has worked amazingly well for the 200,000 miles I have used it. Better then in my newer vehicles. I always assumed that because it was an old R12 system.

Now I find out it was converted to 134A. So, I have AC system oil all over the floor. I have to put in a new evaporator and have no idea what system oil was in this thing?

Note - this system worked great before I destroyed it with a drill. No need for improvement. I just want to get it back to the way it was. Back in the days when R12 to 134A was common - we had to use ester oil. Newer systems use PAG. Original R12 systems used mineral oil. I have to add oil to this system and it has to be - I guess, one of three choices. Ester, PAG, or some stuff I never heard of before called "double-end capped PAG." I wish there was some way to tell what the old oil is that is all over my floor right now.

Pretty good mouse nest around the evaporator. Amazing it worked so well.

I know a guy that was going to mount a fire extinguisher in the cab of a pretty newish IH tractor. He drilled into the cab by the door close to the floor to put in a self tapping screw. Hit the AC line going to the top of the cab. Lost all the freon. Had to tare it half apart to replace the line. Also he thought the heater core up on top was leaking. It wasnt. just a loose hose clamp but he thought while he had it apart to put in the new heater core. $500 for that. I pressure tested the old one and there was nothing wrong with it except the loose hose clamp. Also had to have a guy come to recharge the AC. Things happen.

You need to use PAG oil. R134a was factory in your truck, all manufacturers had to use it in '94 models. Some, such as Toyota, used it in '93. I would only add a couple ounces to the new evaporator, you did not loose the entire oil charge, not nearly as much as it looks like. Adding the full system charge will result in an oil logged system that doesn't cool well.

You dodged the bullet...

Your truck wasn't converted from R12... by '94, R134 refrigerant and PAG 46 oil were factory issue.
Source

The evaporator will usually hold 3 oz of oil, pag 46. Be sure to pull a good vacuum first before charging. I would replace the drier because it has been apart, they usually hold 2 oz of oil.

I have the Ford service manuals for 1994. Two big books. Big as they are I find a lot of diesel-only stuff either left out or incorrect. The Ford tech manual for model-year 1994 says it used R12. I guess I have to go look close and see if the 134A fittings look OEM or conversion add-ons.

I just had a heck of a time trying to get the front wheel bearings out because what I have is totally different then what the 1994 Ford manual shows. So maybe the AC info is wrong too?

Ford manual besides saying my truck uses R12 - also says the evaporator has a color-code RED orifice-tube. The one I found in mine is color-code BLUE. So, I am just more confused. I am convinced that even with 400,000 miles - I am the first person to ever have this evaporator out. It is quite a job to remove.
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Interesting. By 1994 R134 was pretty much the industry standard across the board, from autos to trucks to heavy duty vehicles and construction and farm machinery.

NOT sure if the use of R12 systems was even allowed by the EPA at that time.

Any chance the vehicle and or the manual are Canadian?

According to what I was told back in 1992, the 1993 models would likely be changing over to the "new" R-134a refrigerant about mid-year. The factory rep said that all of the 1994 models should be using the R-134a. since ford does not print their own manuals, the reference to R-12 could be just a misprint from being held over from previous years. As it turned out, all of the 1993 models that I have encountered used R-12 and the 1994s used R-134a.
Of course, there are always exceptions.

134A refrigerant was offered as an option as early as 1992(start of the ninth gen F series). I thought it was likely standard by 95 or 96 year models.

If the truck in question was factory R12 then it needs to be flushed out for conversion to 134A. Original equipment for about all manufacturers 134A systems is PAG oil in whichever viscosity.

Something to take note of is that 134A will work ok with PAG or ester oil...not the old R12 refrigerant oil(some sort of mineral oil I think)...R12 is not compatible with PAG oil..however it will work with ester oil.

Moral of the story is that on an R12 to R134A conversion flush them as good as possible with AC flush and use whichever PAG the compressor model needs. If doing a simple 'red-neck' conversion R12 to R134A and you are not sure you have all the old R12 oil flushed out..use ester refrigerant oil. If you're re-using an old R12 compressor be sure and remove it and drain as much oil from it as possible...flush it out if possible..and refill with some of whichever 134A oil you are going to use in the system.

Apparently many R12 equipped vehicles from the 1990's must have came from the factory with ester refrigerant oil in them...as many many folks just filled them up with R134A and got on with it(and the compressors didn't seize-up!!)

Just remember that the old R12 oil will not work with 134A....and that R12 will not work with PAG oil....ester oil will work with either one.

All I can find it was 134A from the factory.

You can take the evaporator out by removing the cover closes to the valve cover its tight but will come out. The inner fender would have to be removed. You have to elongate the top bolt hole to get it back in.

About the only safe place I could pop a hole in the firewall was on the drivers side I will take a pix...

Manual came from Dearborn, Michigan is was printed July 1993. My truck has a build-date of September 93. First page asks for users to send in any complaints about possible errors in the manual. I guess it is a little late for me to reply to Ford now?

I had trouble with the front auto-locking hubs and bearing-locks. Nothing in the 1994 manual like what I have. I finally found what I have in a 1995-1996 manual for super-duty 250s.

I used to think factory-manuals were the true source for correct info. Guess not.

R12 was not banned till the end of 1994 so some early 1995's "could" have R12.
What I think you guys are tripping over is Ford stopped using R12 in F150's with the 1993 model year.
They still used R12 in the 1994 F250
Same thing with air bags.
1994 F150 had air bags. F250 did not.

With that said if it was converted over to 134 as evident from the non original compressor we need to assume the system was flushed and PAG 46 oil was used.

Where the grey RTV is.





It is a little tight.

Would it be in the budget to go ahead with a new compressor while you are this close?

At that many miles, it has to be near the end.

Then you could take the condenser out, flush it, dump it out, flush the lines, everything would be empty of questionable oil.

I had thought about it. Compressor and condenser. But I figure I have to draw the line somewhere. I just put a lot of new parts in the truck and the AC is one of the things that had been working great - until I killed it. I had the compressor off last week to put the new power-steering pump and steering-box in. Compressor felt good when I turned it and the idler-bearing for the clutch felt like new. So maybe it has not had a lot of use and was replaced before I got the truck? I put 200,000 miles on it but never used the AC much until I moved to northern MI three years ago. Hard to believe that as cold as this place is in the winter, our summers are warmer then what we had in the 40 years I lived in central NY.

Inspect the expansion tube in the evaporator for contamination if its clean no reason to go after the compressor. If not then YES.
BTW make sure the replacement evaporator has a new expansion valve (orifice tube)