Mixing AC compressor oils - how bad?
 

Yesterday I finished up re-seal of the AC compressor in my '87 124.193 (shaft seal had failed, sudden discharge of system).


The system has had PAG-46 compressor oil in it, but I made a mistake and re-filled the compressor with mineral oil. I put in 50 CC of mineral oil, and then proceeded to put in two cans of r134 (had planned to use EnviroSafe propane / butane blend but realized too late the I didn't have enough on the shelf).


So, what to do? Flush the system of all oil, and start over, or ???


Does the PAG oil get carried around the system by the refrigerant, and the mineral oil mostly stay in the compressor? If this is true, I'm wondering if I can take it to an AC place and have them evacuate and pull all or most of the PAG oil with that operation, and then I can switch over to mineral oil and not have to flush all the components.

Don't expect evacuation to remove more than a trace of oil.

If it works then leave it alone. You may be able to bridge the 2 non compatible oil by adding a bit
ester oil. Google it for more info.

Reading the MB service bulletin for converting from r12 to r134, they say to run the AC system on high for ten minutes, shut off and evacuate r12 with recovery machine for 45 minutes, re-fill with r12, repeat process of run and evacuate / recover. I suspect this process removes most of the original mineral oil that was used. Once this is complete, add proper amount of PAG oil and refrigerant.

It looks like the present charge of r134 will not move the mineral oil around, but will move the PAG-46 oil around.

What a mess.

Mb:

In the event that you have not run the compressor, consider removing the compressor, dumping the mineral oil that you put in, rinsing with a bit of PAG, dumping that, and then refilling with PAG.

Mineral oil will not circulate with HFC refrigerants, basically the compressor will pump it into the lines where it will stay, not returning to the compressor. Not only will it oil-log the coils, but you reduce the amount of oil in the compressor sump potentially leading to seizure of the compressor.

Evacuate and flush the system, drain the compressor, and start over. If you want a universal oil use PAO or POE oil. Both will circulate with HFC, CFC, or HC refrigerants. PAO has the added benefit that it is not hygroscopic (won't absorb moisture from the air).

At this point my plan is to remove / drain / flush the compressor and the condenser and the lines from the compressor to condenser and from condenser to drier.

According to Enviro-Safe FAQ, their refrigerant is compatible with all compressor oils. Denso recommends the PAG-46 oil with this compressor, which is what I have been using and have not suffered a compressor failure after a couple years of use.

Be aware that Enviro-Safe is nothing more than propane with pine scent added.

My understanding is, ES is a blend of butane and propane with other chemicals for a good R12 alternative.

R290 for home R22 and some small portable AC units use pure propane...

Last I checked , R290 / propane isn't legal for a building AC retrofit and is limited to some small amount for new builds.

ES has a university ( student ) paper they use to show what they are selling is " safe ". https://www.es-refrigerants.com/resources/docs/PERFORMANCE%20AND%20SAFETY%20OF%20LPG%20REFRIGERANTS.pdf


It is mostly junk science as it uses the outright cost of R12 to offset the cost of insurance ( Page 15 ) and claims that an explosion in an occupied car will:

A real test
https://www.youtube.com/watch?v=FO47SzxJmV0

Hydrocarbon refrigerant flammability test archive footage
on the channel VASA
~~~

All we need to do is substitute professor Honeydew as the presenter and his long-suffering assistant Beaker as the guy in the car. Or maybe Phil from " Better off Ted " in the car.

https://www.youtube.com/watch?v=DjtowzVzl_4

A video of a hydrocarbon refrigerant demonstration which wen
on the channel LOPMAS

All ya'll Enviro-Safe haters can just keep on hating, and put what you like in your car. I'll put what I like in mine.

Fair?

The original post and question are about the proper oil to use, and I'm satisfied that the answer is PAG-46. I'm probably going to splurge and get the Denso stuff for about $20 for 500 ml, as it is double-capped and much less hygroscopic than FLAPS PAG-46.

Just found another source of hydrocarbon (flammable) auto refrigerant, FrostyCool:

Wholesale Refrigerant - Cheap R22 Freon, R22a, R410a, R12a, R134a Replacement

Looks like they are about $10 per case cheaper than Enviro-Safe.

So you are saying that if ES caught fire in a car you were driving and you were so badly burned you could not work, you would not sue someone? How about your passengers? Do they consent to riding in a car with an unsafe refrigerant after you have informed them?

post 25
https://hvac-talk.com/vbb/showthread.php?1584811-Enviro-Safe/page2

Enviro-Safe provided a good real life example of what happens when ES-22a and like accidentally ignites. Last year, Enviro-Safe second generation refrigerant gas thingy caught fire in its own re-bottling plant and caused a serious industrial accident. Four injured. Two life flighted to hospital. It blew off the building's roof and a portion of the wall and it had to be demolished. Oh and a couple months later, EPA gave them a violation notice for selling illegal refrigerants.

I wasn't hatin' on it, just making sure you knew. Some people think it's some sort of magic potion (it isn't). I ran it for a while in my SDL and it worked fine when moving, didn't work well for me in low humidity high temp low speed driving though. Ironically 134a works better for me in my climate so I've stuck with it.

About 70% of new refrigerators for residential use are operating with HC refrigerant; but of course may not be installed in a kitchen that also has a gas stove, right?

No, actions and risks that I take / accept are my responsibility, I'm not one who tries to hold others responsible for my actions. I own it.



Life is full of risks. We all make choices, and weighing the risks is one of them. Do you never speed? Have you never followed another car maybe just a little too close? You take risks in your daily life, just like all the rest of us. I would submit that a life with no risk would be a very dull and boring life. My point is that we all accept some risk, so now the question is what is the level of risk vs. the possible reward that one is willing to live with.


The evaporator is buried in the heater box (plastic) which is buried under the dash, pretty much in the center of the car. Any collision which is going to penetrate / deform the heater box to the point that the flammable gas escapes from the evaporator (and only the evaporator) would almost certainly cause major injury or death to the front seat occupants, so a post-collision explosion is not a concern in my book, at that point. The scenario is just so far fetched.


Any leak in the engine compartment which may result in an explosion or fire is probably not going to cause any harm to vehicle occupants. Another very small risk that I'm willing to accept.


Actually getting the escaping gas to the correct ratio of oxygen / fuel so that it will ignite, and also having an ignition source present, is a pretty tough set of circumstances to set up.


Now, do you drive a gasoline-powered car, or ride in a gasoline-powered car? THAT is far more risky, in my book, in terms of a post-collision fire.

A kitchen is a completely different operating environment. The risk of a crash is minimal and interior volume large compared to a car.

By federal law, HC charge is limited to 2 OUNCES and only in 100% new self contained equipment. Any inside / outside system like a split or whole house AC isn't legal. A metal tube / soldered joint whole house AC system has much less chance of leaking compared to an automotive environment so why would it be advisable to charge a car with HC ?

A household fridge has a sealed compressor motor but does have an enclosed , but not sealed , snap thermostatic switch that could produce a spark. A car has an arcing / sparking DC blower motor directly in the air flow path. What one do you think is a greater ignition hazard?

What position does Mercedes take on very flammable refrigerant like HC?

What stance did MB take on the somewhat flammable R1234yf refrigerant when it first came out?

https://hvac-talk.com/vbb/showthread.php?1751241-propane-r-290-being-used post 9


https://hvac-talk.com/vbb/showthread.php?1751241-propane-r-290-being-used/page3 post 35