firemn131

Early 87 S4 Auto, no rear AC

Never worked an AC system before.

Putting systems back together. converting to 134.
All new hoses, xpansion valve, condenser, Compressor rebuilt with Ester oil for packings.

Hoses and condenser have been thoroughly flushed and cleaned.

Ready to put hoses and parts together prior to engine install.


Question..
When do I add the Ester oil.

I will have the vacuum pulled at a later date obviosly prior to charging system.

If I add the oil to the compressor now then complete the connections and cap off to avoid any secondary moisture, will the later vacuum pull out the oil also?

When I do add the oil, can I add it at any part off the system or does it need to go directly into the compressor?


thanks,,almost there.

WallyP

This might not be easy...

Per Page 87-90:
The 6E171 compressor requires 260 - 300 cc of Oil.
The 10PA20C compressor requires 100 - 140 cc of Oil.

I am assuming that is actually the total amount of oil in the system. I have seen no other oil spec...

IF you know how much oil is in the compressor now, and can compare that to the spec, and the compressor now contains the specified quantity of oil, you are good to go - perhaps.

Per Page 87-103:
On an operating system, the compressor contains 40% of the oil.
The Evaporator contains 35%.
The Condenser contains 15%.
The receiver/dryer and lines contain 10%.

All you have to do now is estimate how much oil is left in the system, and where.
If, for example, you have used the existing evaporator, and it hasn't been flushed, that is 35% still in the system.
If you have a new receiver/dryer (you should!) and have flushed most (?) of the lines, then you need to add 10% of the oil to the receiver/dryer.
You should add 15% of the oil to the condenser.
You should drain the compressor and add 40% of the oil.
That should get you close...

Hope that this helps!

firemn131

Higher Math..oh man my head hurts..I was just hoping i could dump 4 or 6 oz into the compressor..
New dryer, expansion and clean dry lines and coil...

I just finished closing all of the lines up and installing the dryer and coil...I may be able to add a bit to the dryer, the expansion valve is still accessible..I think the lines will just have to absorb from whatever flows..

WallyP

An approximation is good enough on the various locations - the oil moves around the system in operation. Just use the proper total amount, with the approximate amounts in the condensor, compressor, and receiver/dryer.

dr bob

Following on to what Wally shares, I add the compressor oil to the compressor, in a flush/fill process that includes draining the old oil out, adding new oil, drain, refill, drain, refill, drain, then add correct amount of compressor oil and put the compressor in place.

The rest of the system oil is added as part of the evacuation process. With vacuum on the system long enough to boil any moisture out, oil is drawn into the system through the high-side port at the drier manifold. I dip the end of the middle hose on the charging manifold into the oil in a measuring cup with the oil in it, and let it slurp the oil into the drier and the condenser that are on either side of the high-pressure charging port. The drier and the evaporator are probably the largest collection places for oil in the system after the compressor, so adding to the drier and evaporator means the oil will distribute itself "correctly" once the system is in service. Once the oil is in, continue drawing vacuum on the system at the low-side port for a while, then open to the high-side port and let it work the pressure down again prior to adding refrigerant.

Immediately before starting the car and running the system the first time, I suggest that you MANUALLY rotate the compressor a dozen revolutions to make sure there are no slugs of oil trapped in compressor cylinders. Oil in a cylinder will damage the compressor instantly, so best to be sure the cylinders are clear with that one easy step.

firemn131

Thanks Wally, and Doc,
I was hoping you two would chime in.
I have left the compressor hanging, I will add the oil tonight and close it up.
Engine dry run install tomorrow I hope..

I may just take it to my local P mechanic to do the evap and charging next month. I think this may be best left to a pro..
More for piece of mind too I guess.

260 - 300 cc of Oil.

I will work to get some approximations to add oil to the Dryer.
I closed the expansion valve last night. I may have extra o rings, if I do I will juice it up a little also..


Thanks again..