I was looking to see if someone could assist me with the correct manner in which to add new refrigerant oil to a rebuilt AC system. I'm working on a 69 442 with factory AC and everything is either new, rebuilt or flushed. The compressor is a new original style reman (A6 I believe?) the evaporator was flushed, the POA was flushed and recalibrated to work with R134A, the hoses were reproduced using the original muffler and with hose for R134A and the condensor, drier and expansion valve are new. So the system is completely dry now. I have the correct oil for 134A but I'm not sure how this should be added. Should this be done when the system gets charged or should I put some of the oil into the compressor now? The hoses are not yet installed. If I should add oil now, how much? And where should it go? The CSM shows it being added through the fitting on he side of the compressor that almost points to the ground so I would need to remove it. Or can I pour it into the rear ports for the hoses? The CSM makes reference to a total of 10.5 oz of oil but then it shows a breakdown of the volume of oil by component and it falls short of 10.5 oz. Since it will use 134A, is the oil installed in the same quantity as if it were the R12 system? As you can see, this is not my area of expertise! Any help is appreciated.

 

If there is a drain plug fitting add the oil there. Yes it needs to be off the engine to do so. It can also be added to suction side of compressor if no other fill port. Add the oil then install unit and it can sit till vacuum is pulled on the system before charging.

 

Thanks Oldsmaniac for the reply.

 

I would add a bit to each component, as it says in the manual, including to the oil pan of the compressor and the excess to the receiver. You want to avoid the compressor trying to compress a cylinder full of oil, as that would be bad.

- Eric

 

Thanks Eric, I think I'll give that a try. This should hold me over until the system can be drawn down and charged by a shop with more experience on this matter than I have. Until then, the oil should keep things from drying out.

 

A small amount of oil is always circulating thru the system is. Most oil is always in the compressor crank case. The oil does no component any good but the compressor for lubrication. Some oil does get trapped in the system and may be found in the evaporator and accumulator etc. Any oil returning to the compressor is done so thru the suction side of the compressor and it is designed to so. It is not designed to get a slug or large quantity of oil in a short time as this could damage the running compressor. Vapor is compressable but not fluids. If a small amount of oil was added to each component there is no way of knowing if it would return to the compressor and there would be the proper amount there for lubricstion. I would add the required amount to the compressor and be done with it. My 2cents along with my refrigeration background....

 

Thanks for the ideas. I think I'll just put recommended quantity of oil in the compressor and let the AC shop take it from there when the time comes.

 

You mention getting it evacuated and charged at a later date, and that the hoses are not yet installed.
I wouldn't let it set open to the atmosphere for too long after you have added the oil. Moisture is your enemy when it comes to refrigeration. Although a thorough evacuation before charging is designed to remove moisture, the evacuation process could run into many, many hours under vacumm if there is excess moisture, and yes, the oil will draw moisture from the surrounding air.
Make sure your shop uses a micron guage and gets the system down to the proper level, no matter how long the evacuation takes. Otherwise all your work and money goes for a poorly operating and inefficient ac system in your pride and joy car!!

 

Long story short....
IDEAL method.
pull a vacuum on the system
break the vacuum with oil
pull a vacuum on the system again

When you take it to the shop to be charged, whether a month from now, or a year from now, it should still be in a vacuum if you have no leaks.
No lost 134a, (money!), and no excess moisture that the shop has to work long hours to remove, (money!)

 

Thanks for the info lansing. The system, although not fully completed, has been sealed at each step of assembly. Only the hoses need to be installed, and the hoses are sealed too. Just before the hoses get installed, I'll add the oil to the compressor.