I've been searching lots of sources for an answer. This seems like the best place to set me straight.
I'm rebuilding a 1970 f250 4x4. Along with other improvements I'm adding A/C. I'm installing parts from different sources. The evaporator is an under dash dealer installed (I think) unit with TXV. All the other components are new. Sanden sd7h15 compressor has 5oz. of oil in it. and it appears that I need to add more pag 100 oil to each component. Condenser = 2oz. Evaporator = 3oz. Receiver drier = 1oz.
Sound like I'll have the correct amount of oil in the system?

 

What happened? Did I scare everyone away?
Sure would like to know about the oil.

 

Well, that is a tough one to answer, because in effect it is a custom.

These days, the total system charge of oil is in the compressor as shipped from the compressor manufacturer, and at the auto assembly plant, they drop them in and connect them up and evacuate. They don't add oil to different components in the system.

The oil charge amounts listed in manuals for particular A/C system components is a guide when replacing a particular component. The person fixing it puts the X amount of oil into the component being replaced, to keep the total system oil charge in the ballpark.

When I totally replaced the whole A/C system in my Bronco last spring, I took the shipping plate off of the new compressor, cranked out all of the oil into a measuring cup, and threw it away. Then I measured out 7 ounces of fresh oil (the system charge for my Bronco with FS-10 compressor as per specs) into the compressor.

I replaced the oil it was shipped with, because I really had no idea how long the compressor sat in Denso's consumer stock. For compressors shipped to an auto assembly plant, they would be produced J-I-T and not have to concern themselves with oil picking up moisture while sitting around.

After installing the compressor, I hand-cranked the shaft about 15 turns CW to clear the cylinders of oil.

So in my situation, the total system oil charge needed was known.

I don't think I would add all that oil to different components as you listed, that sounds to me like a combination of two different methods, and I would expect you would end up with too much oil in the system. Too much is not good, just as too little is not good.

I think if I were you, I would be looking at Sanden's website and seeing what they say. It is possible that the 5 oz. is the total you need, but it would be nice to see that specified by Sanden.

 

Thank you Torky2. Your response is appreciated. It seems you've confirmed my skepticism. So..... I still need to find an answer or risk destroying a compressor or overcharging the system with oil and finding strange symptoms yet to be discovered. I'll try to contact Sanden and see if they'll help.

 

Here's some info about this I found on the Sanden USA website. Since I don't have anything special about my system like longer hoses it seems like I should follow this info. I'll have to take the risk that 5oz. is enough.

Important Sanden Compressor Oil and Refrigerant Specifications
1. New Sanden compressors are shipped with all the oil required for a normal OEM system for which
they were intended. In most cases no additional oil should be added. For R-134a A/C systems the
original Sanden PAG oil shipped in the new Sanden compressor is the best lubricant for compressor
durability.
2. For a few rare cases such as very large A/C systems with long hoses which use more than 4 pounds
of refrigerant, additional Sanden oil may be required. Consult the OEM manufacturer’s specification
for oil and refrigerant quantities.
3. All Sanden R-134a SD7H15 piston compressor models use Sanden SP-15 PAG oil for service.
SD5H models are shipped with SP-20 PAG but can be serviced with SP-15 PAG. Chrysler TR Scroll
model compressors also use SP-15 PAG oil for R-134a.
4. All Sanden R-134a compressors SD7B10, TRSA12 for GM, TR Scroll for Honda, SDV and PXE for
VW and other PXV and PXE models use Sanden SP-10 PAG oil.
5. All Sanden R-12 applications use Sunico 5GS mineral oil which sells at refrigeration supply houses
and is not available from Sanden.
6. Sanden’s part # for SP-10 PAG oil is #3201-1996 and SP-15 is #7803-1996.
7. SP-10 PAG has a viscosity of 46 centistokes at 40 deg. C. and SP-15 PAG is 80 centistokes.
8. The use of other oils such as Ester, often called POE, or refrigerants other than pure R-134a or R-12
will void the warranty.

 

Great! Sounds like you're good to go!

IIRC, my Bronco's spec was 34 oz. of 134a, which is 2 1/8 lbs., a long way from 4 lbs. of refrigerant.

If you had a van with a rear evaporator and long tubing to get back to it, then there would be a lot more volume for oil film to cover, but as the refrigerant volume (weight) would increase also in that type of application, tying the needed oil amount to the refrigerant amount above some threshold makes sense.

 

Thanks again Torky2. The numbers you give lets me have a little more confidence that I wont oil starve my new compressor.
I really wonder what info the system designers at the factory use to determine how much oil their systems require.