Refrigerant oil

[Gordon Maney]

My 2001 Ram has a tag on it calling out a particular refrigerant oil for the A/C. Is this oil peculiar, or is it a common refrigerant, oil widely used?

[712edf]

I think refrigerant (freon?) is available with & without a lubricating oil. Those that have it usually say so. If a system is low is sometimes ok to add straight refrigerant. If a system is empty I think its best to put the type that contains the oil in...Not sure if there are different types of oils.

[Desoto61]

If I remember correctly, there are two different types of refrigerant oils that are/were used with R134A (PEO, and PAG), so this may be a case of them not wanting you to mix types in the system.

PEO seems to be used if you are trying to "convert" an old system since it works with older systems while the PAG oil is only good for R134a but works better with it.

Most of the cans you get at the parts store have some oil in them since the oil/R134a mixes in the system, so a leak of refrigerant will usually mean some oil leaked with it.

[Gordon Maney]

If adding, single pound cans are OK. If you are discharging, evacuating, and then charging, you need to put oil in, and any commercial operation will be using bulk containers of refrigerant and adding the oil separately.

I learned that a guy at work has gauges and a vacuum pump, so I can do my truck in his shop. I used to do a lot of A/C work as a mechanic, but have never owned the items necessary.

[Desoto61]

If you really wanted to have the tools, Harbor Freight has guage kits for $40 or so on sale every so often, and a compressed air operated vacuum generator (seems counter-intuitive but they do work) for $15 or so.

Far from pro quality but works fine for home stuff. Of course if you need to remove refrigerant you need a shop with recovery equipment, but for empty systems or topping off yours with the little cans it works well enough.

No reason to spend the money if you can use them for free but if not it's an option.

The obligatory safety statement: the high pressure side of these systems is HIGH pressure, and the PAG oil is highly hydroscopic (absorbs moisture) and can at minimum be an irritant on the skin or worse if it contacts eyes, nose, mouth, etc. Plus R134a isn't good for you or the environment, it's just not as bad as R12. So as always be careful.

[712edf]

Gordon, and others as well. A/C tools are some of the most useful, yet most overlooked tools you could own. While not much handy on flat-fender rigs, most cars & trucks since late 60's came with air conditioning and that seems to be an area that DIY folks don't often dabble in. The know-how is of course applicable to home A/C systems & refrigerators, even if the tools are different. Around here if you can fix air conditioners (car or home) you are a sought after guy.

Only downside is the aforementioned regulatory crap that killed R-12 to begin with. R-134 replaced R-12 in autos at about the 1994 year model. My old 93 Cherokee had R-12 that I replaced myself with R-134 using stuff off of autozone's shelf and a hand-powered vacuum pump. Didn't do all the "recommended" hardware flush/changes that they say MUST be done for a successful conversion. I just screwed on the port adaptor & put in the new stuff. Worked perfectly.

[Sickcall]

vacuum pump

On one occasion I had to evacuate my system to recharge it after soldering a hole in the evaporator. I did not have a vacuum pump so I hooked a hose up to the intake manifold which pulled it down to 22 in. Not a complete vacuum or far enough by the book but the rest of the non condensibles I could vent off after it was pumped up. Had no problems for years after that.

[Gordon Maney]

On one occasion I had to evacuate my system to recharge it after soldering a hole in the evaporator. I did not have a vacuum pump so I hooked a hose up to the intake manifold which pulled it down to 22 in. Not a complete vacuum or far enough by the book but the rest of the non condensibles I could vent off after it was pumped up. Had no problems for years after that.

That is really fascinating. I am unclear as to your meaning regarding the rest of the non condensibles.

[712edf]

That is really fascinating. I am unclear as to your meaning regarding the rest of the non condensibles.

I suppose he is refering to any contaminants which may have been introduced into the system, a contaminant being anything that doesn't evaporate/condense within the same pressure/temperature confines as freon. These contaminants could be anything that is suspended in or that is contained within the make-up of atmospheric air, including but not limited to oxygen, nitrogen, moisture,etc...Since these elements would hinder the refrigeration process by taking up space (volume) that should be ocuppied by freon they are considered contaminents. They themselves may be condensible, but not within the parameters of the system.

They possibly may be bleed off in the manner that one can bleed water vapor out of an air compressor, not sure.

At least that's what I took his statement to mean.

Nice touch using manifold vacuum. My grandpa used to have an attachment to use air from a spark plug port (compression) on a running engine to air up tractor tires in the field.

Bucky