Oil for Mopar A/C compressor?

[ExDelayed]

I found it has drain and fill plugs. Im sure I should just leave well enough alone, but the oil in its tiny crankcase is 26 years old and for some strange reason, that just irritates me.

I believe I heard once before that it takes a 30w oil. I do not know if it takes a ND 30w though. Its total capacity is probably about a quart.

Any ideas?

-Jon

 

[MolaKule]

Purchase a quart of Amsoil compressor oil (from one of our sponsors) in the ISO 68 viscosity weight.

 

[RobY]

I would live with the irritation. If you open the compressor you will lose the refrigerant charge and take another bite out of the ozone layer. It will cost you to recharge the system, and you will likely need to replace the refrigerant dryer as well since atmoshperic moisture will find its way into the system when it is opened.

The bulk of the oil in the system is not in the compressor, so changing the oil in there will do little good. To get all the old oil out you would have to flush the entire system to carry the oil out of the heat exchangers.

Also, I would not use the Amsoil product unless it was qualified for A/C compressors, not air compressors. The refrigeration oils are a separate category of compressor oils. You may still be able to find mineral based refrigeration oil (used with CFC-12)in an auto parts store, but most of the lubes on the shelf for A/C will be the new PAG or polyolester oils for R-134a refrigerant.

 

[tdi-rick]

Pretty much what Rob says is correct, (except there is more oil in the crankcase than the rest of the system

) just let it be.

The oil is under the same pressure as the refrigerant, so if you remove a plug you will end up with a face full of oil and gas. Not nice.

Air conditioning/refrigeration oils have a moisture content below 30ppm, I doubt very much if the Amsoil compressor oil is this low. This is critical for the continued functioning of the system as the moisture reacts with the refrigerant, creating acids, and then it's all down hill from there.
They also have additives to make them miscible, to a certain extent, with the refrigerants they will be used with to enable their return to the compressor once they leave.

The correct grade, and most widely available oil is Suniso 5GS which has a viscosity, SUS/38*C 525. (But of course, you're not changing it, are you

)

Rick

[ February 12, 2004, 04:19 PM: Message edited by: tdi-rick ]

 

[Kestas]

Automotive a/c is one system that should not be touched unless there is an obvious problem. Do not try to perform maintenance on it beyond cleaning the condenser of debris or checking the pressures.... and even pressure checking should be kept to an absolute minimum or avoided altogether if the a/c is blowing cold.

 

[ExDelayed]

I decided not to change it. I was to the point of putting the truck back together when the first replies came through.

I figured if it kept bugging me, I would look into it again at a later date.

Though there still is the R-12 to R-134a conversion that I want. It will have to get it at that time.

 

[ExDelayed]

But of course. We have yet to see a day above 35 here for almost two months.

That question will be better asked in about a month or so.

 

[RobY]

ExD - You may want to think over the retrofit choice as well. I am assuming you would want to retrofit when enough refrigerant has escaped to require a recharge. If the system is tight (takes several years to leak out enough refrigerant to lose cooling) you should recharge with R-12. Even with the relatively high price of R-12, you will be happier with the results. There is still a lot of R-12 out there, so it will not be too hard to find it if you need it.

If the system leaks too much, or fails through mechanical problems, you should repair the system and then retrofit to R-134a. During the repair process, you can clean (flush) and replace any components so they are ready for R-134a and the new PAG or POE lubricant.

There is minimal retrofit process used where all the old mineral oil is left in the system and a full charge of new synthetic is added on top. This is the type of retrofit you can do yourself with the packaged kits in the auto parts stores. I would avoid this type of retrofit procedure and have it done right.

 

[Kestas]

Is it blowing cold?

 

[Chris142]

quote:

---

Originally posted by RobY:


There is minimal retrofit process used where all the old mineral oil is left in the system and a full charge of new synthetic is added on top. This is the type of retrofit you can do yourself with the packaged kits in the auto parts stores. I would avoid this type of retrofit procedure and have it done right. [/QB]

---

Ya what he said. Stay away from the R-134 stuff that says that it contains sealers too. I cant recycle this stuff w/o voiding the warranty on my a/c machine. I wont touch a car that has a sealer in the system.

Gettin tough to get R-12 here. I don't see enough cars to warrant buying a 30 lb cylinder @ $35.00 a lb my cost.