I have a truck, info is in my sig, and the A/C system has lost it's charge. I haven't had the truck too long and don't know how long it's been since it's been ran. I have a little background in A/C and refrigerants so I just have a couple of questions. Since this system leaked down to atmospheric pressure, how do I go about removing the oil from the compressor? I might have to remove the compressor but was trying to avoid it. I can if I need to. I know that it's R134a and it uses POE oil that is azeotrophic so you can't remove all the water and the remaining water will turn to sludge and acid. I know that I should probably change the drier and all the o-rings, but is there anything else that would need to be changed?

I know that the pressure switches are good, or at least the low pressure, because when I put some refrigerant in my girlfriends car because of a leak, I put the rest in my system to see if I could get the system to turn on and cycle. It did and I shut it off. The system was at 0 psig when I put the gauge on it and it took about 3 weeks for it to complete leak back down to 0. The compressor sounded good so I would think that it would just be a small leak. I think that the low pressure switch saved the compressor when it was low on charge. Am I overlooking anything? I have a manifold set and a good vac pump. I think I can just charge it back up to factory charge after I fix the leak and go from there. Any help or feedback would be greatly appreciated. Thanks in advance!

 

Your 95 "should" have an FS-10 (Nipposdenso) compressor. Those compressors don't have a sump, so the oil circulates with the refrigerant. It should also be a factory R134a system, using PAG oil.
To drain the old compressor oil you will have to remove it and actually flush it multiple times with clean oil. You will also need to remove the orifice and accumulator, then solvent flush the rest of the system to remove the remaining oil.
The POE/PAG oil is not azeotropic, the R134a refrigerant is. (The oil actually is too, but in the context of AC systems, azeotropic or zeotropic refers to the refrigerant). This means the refrigerant will not fractionate into seperate gasses like many refrigerant blends.
The POE oil IS hygroscopic. PAG is even moreso. It will absorb moisture that cannot be removed. This is likely what you are thinking of.

Aside from the accumulator and seals, you also need to replace the orifice tube.
Look closely at the compressor body for oil staining around the case seals that would indicate a body leak. Remove the clutch plate and look for oil in the "snout" near the shaft seal that would indicate a shaft seal leak. Both of these leaks are very common with these compressors and require compressor replacement. The case seals are not serviceable DIY and shaft seal replacement only has about a 50% success rate due to wear of the shaft bushing.

Hope this helps.

 

Whoops, your correct on the hygroscopic. I had my head in the clouds and didn't know what I was thinking on that one. I didn't even think about the PAG oil. I'm used to dealing with POE, PVE and mineral oils. I was thinking about adding some refrigerant and backing it up with nitrogen and taking my leak detector after it to pin-point the leak before disassembly. I just want to make sure that it's not in the evap or condenser before I try to replace the o-rings and compressor without that being the problem. I didn't look too closely at the compressor for oil seepage but that would be a good place to start.

Where is the orfice tube be located, by the accumulator? You say that I should replace the accumulator and orfice tube, what about the drier? Would the local auto part store have the solvent flush that would flush this out? How long does it take to get all the oil/solvent out of the system? I live in Florida so it's hot every day till like December but i'm used to it by now so I have no rush and want to do this right. lol. I love the 360 air that I currently get because the truck is insulated well so it stays pretty cool. Is there anything else that i'm overlooking?

 

Whoops, your correct on the hygroscopic. I had my head in the clouds and didn't know what I was thinking on that one.
Yea, I figured that's what you were referring to.

I didn't even think about the PAG oil. I'm used to dealing with POE, PVE and mineral oils.
Automotive R134a systems all use PAG. That stuff is nasty about absorbing moisture. There is a Double End Capped version that is less hygroscopic, but it can be tough to find locally.
POE is usually recommended for R12 to R134a conversions because PAG and R12 don't play well together. Residual R12 molecules leaching from hoses"could" cause problems. I've never actually heard of this happening, though

I was thinking about adding some refrigerant and backing it up with nitrogen and taking my leak detector after it to pin-point the leak before disassembly.
That's an excellent way to do it. Remember, too, that your system came from the factory with UV dye, so if you have access to a UV lamp you can also add that to your bag of tricks. Between the "sniffer" and a UV lamp, not many leaks slip by.

I just want to make sure that it's not in the evap or condenser before I try to replace the o-rings and compressor without that being the problem.
That's a good thought. Evaps and condensers on those trucks aren't common problem areas, but should be checked. The big culprits are the Spring Lock connections and compressor shaft seals.

I didn't look too closely at the compressor for oil seepage but that would be a good place to start.
It's pretty common. When you add your refrigerant/nitrogen mix, wrap the comp in a small trash bag for an hour or so. Then "sniff" the contents. Old leakage doesn't always show up with the UV light on case leaks.

Where is the orfice tube be located, by the accumulator? You say that I should replace the accumulator and orfice tube, what about the drier?
The orifice tube is down inside the evaporator inlet tube. There's a removal tool, but they usually come out with a pair of needle nose.
You're probably familiar with TXV systems with a receiver/drier in the liquid line. Most US vehicles use a Cycling Clutch Orifice Tube system which have an accumulator/drier in the suction line. Replacing the accumulator also replaces the drier.

Would the local auto part store have the solvent flush that would flush this out? How long does it take to get all the oil/solvent out of the system?
Most "real" parts stores carry a good, fast evaporating AC flush solvent. One brand is Dura-141. It's pricy, but does the job well. Lacquer thinner is also a good flush agent but takes a bit more time to evaporate fully.
Since you didn't have a compressor failure, solvent/air flushing will be sufficient. The key is LOTS of compressed air. For heat exchangers, about 5 minutes after you stop seeing liquid is enough. Flush all of the components separately.
I live in Florida so it's hot every day till like December but i'm used to it by now so I have no rush and want to do this right. lol. I love the 360 air that I currently get because the truck is insulated well so it stays pretty cool. Is there anything else that i'm overlooking?

Nope. It sounds like you have all the bases covered. Oh, don't forget to add back some UV dye when you reassemble the system.

At 15 years, I'd recommend replacing the fan clutch. It has outlived it's expected ~8 years. This will improve cooling at idle/low speeds and help to keep the high side pressure down. A weak fan clutch will cause high head pressure which can cause leaks and even compressor damage.

For a lot of great info on MVAC systems, check out Automotive AC Information Forum - ACKITS.COM . The site sponsor, Automotive Air Conditioning Parts & Equipment - WWW.ACKITS.COM is a supplier that I use often.

Good Luck

 

I do have a UV light that I can use. That's another bit of useful information that I didn't know. I'll get after it with my H10 in the daytime and the UV light when it gets dark tonight.

I've never heard of these. Where would the spring lock connections be located?

Yeah very familiar, mostly with R-22, R407c, and R410a. I've messed with R404 but not a lot. I work in an OEM heatpump manfacturing facility and do all the testing on the equipment to verify BTU output at all sorts of conditions.

That's a good thing too. I didn't even think of that one.

Thanks for all the info. I'll try to keep you updated on what I find.

 

Where would the spring lock connections be located?

Looking at replacement parts for your truck, it looks like there is only one. The evaporator inlet is a Spring Lock fitting.
They are a quick connect line fitting used on most Ford products from about 1979 through today.
Some vehicles use all spring locks, some only use one or two. Spring Locks are notorious leakers, especially when they can move around due to engine torque.

You'll need a set of tools to release and separate them:
Automotive Air Conditioning Parts & Equipment - WWW.ACKITS.COM: Spring Lock Release Tool - Mastercool
That type of spring lock tool works best, IMHO. There is a cheap set available in most of the "chain" parts stores made of colored plastic for about $6 that would work fine for you since there is only one. There are a few variations of the tools.

Since you're in Florida, use a Hayden HD or Motorcraft fan clutch if you replace it. The cheaper units are often not much better than a weak original clutch at idle.

 

Alright, thanks! I didn't get a chance to mess with it yesterday and i'm going to be busy this afternoon so it looks like i'll be shooting towards wednesday to the end of the week. Is that tool a fitting to put the spring lock back together or to take it apart. Are they reuseable? If so i'll probably purchase the good set for use in the future. I think that I vaguely remember seeing these on another vehicle but haven't looked at the one on my truck yet. I've never heard of the Hayden HD, I know I can get the Motorcraft. I'll check the local parts store. I know that the belt tensioner needs to be changed so maybe while i'm in there i'll do the serpentine belt, hoses and a radiator flush too. The water pump looks relatively new so I think that might be fine but i'll double check. Thanks for all the good info!

 

The tools are to separate the fittings. There will be 3 orings on the male (hose) end that you will need to replace. There is also a retainer spring that needs to be inspected or replaced as needed. Once you take it apart and look at it, it will make sense. To assemble the fittings, just lubricate the orings and snap the halves together. For about $25, the good release tools are a wise choice. If you get the 6 (7?) piece set, it will have the tools for the fuel lines also. Ford used spring locks on the fuel rails where the hoses connect.

Hayden makes fan clutches and other cooling system parts. It's a "better" brand often carried by parts stores like NAPA. There is usually a standard duty unit available, which is about like the OEM clutch. You'll want a HD (Heavy Duty) unit or even an SD (Super Duty) clutch if available.Going with a heavier duty clutch is a good upgrade for vehicles in very hot climates like yours.
The main thing is to avoid off brand, store brand or white box units at the lower end of the price scale. While tempting, they often don't perform well at idle, where the AC needs it the most. The AC performance will suffer with a marginal fan clutch long before the engine temp is effected.

Good call on the belts, hoses, tensioner, etc. Those are "while I'm in there" maintenance items that I would address too. With the fan and hoses out of the way, it's very easy to pull the condenser for flushing off the vehicle or to clean between the radiator and condenser.

I'm glad you find the info helpful. If you have any other questions, just ask.