I’ve been working on upgrading the 85sd ac system. I’ve replaced the evaporator and expansion valve, dryer, new compressor(R4) a Klima condenser kit.
And of course performed a good flush on the hoses.
Pressure test with Nitrogen and a hard vacuum.

So my question is on putting in the oil, I believe it’s 8oz correct? Also I will be using a jug of 134a.
Do I charge with vapor(jug upright) or liquid (jug upside down)?
I thank you in advance,
greazer2b

I have a new R4 compressor ready to go in my SD. If I remember right, the directions on the compressor say to dump about half the oil out and put that exact amount of oil someplace else - maybe in the drier bottle (? do not quite remember).

And you are using Freon and not R134a? Not sure what your comment about 134a meant.

The quantity of oil, IDK.

I've always added the oil directly to the compressor during compressor replacement and rotated the compressor by hand as per the compressors included instructions.

I'd charge with the can upright pulling it in through the low side.

Leak testing with nitrogen is a pro move, good work

Vacuum it well to boil off any moisture.

Wear gloves and eye protection.

Hopefully the system has a sight glass, it make life easier.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Yes I’m using R34a. And I followed the compressor instructions about draining out all the oil it was shipped in.

This will be first time Im starting out with a fresh system, before I always topped off with small cans. But this time I’m using a #30 jug of R134a that’s why I was asking do I charge with it straight up?

And yes there’s a sight glass on the drier but I’ll also be using a scale.
As for the oil I plan on using Ester.
Thanks again
greazer2b

Yes still upright so that a compressible gas enters the system. Upside down would introduce a liquid and probably bend and/or damage internals in the compressor similar to hyda-locking an engine.

Let us know how cold it gets!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Make sure you pull a good vacuum for at least an hour and don't get any air in system when you charge it.

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Jim

X2, it is good to have valves in the charging hoses that allow switching from the vacuum to the refrigerant charge within a line that remains under a vacuum. This prevents air that would be in a separate line being introduced into the system.

Charging stations were plumbed this way, refrigerant in the graduated cylinder was visible, could be heated to increase the pressure in the cylinder and then a valve would be opened putting the refrigerant in through a hose that was under a vacuum and moisture free.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

How does R134a work in the 1985 compared to freon? Is it different from the earlier SDs where R134a does not provide sufficient cooling?

I suspect it needs a p-flow condenser to work well.

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Jim

Just what I thought.

Greaz - you should read up on posts about how poorly R134a works in the standard AC system for an SD.

Is there some reason you are switching over from Freon?

Beware.

Yep that’s what I’m using 16x24.

I’ve been going back and forth on R12 or 134a. Seems with the new PF condenser it’s time to give 134a a try.
Thanks for your imput
greazer2b

I charge 134a with the can upside down. The chances of slugging a car compressor is extrememly low.

When I did mine, (r4) I put 4oz of oil in the compressor through the vertical suction pipe at the compressor. Then hand turned over the compressor about 20 times. After that, while keeping a vacuum on the system, fed the last 4oz into the low fitting with a tiny funnel.. Closed it up and let vacuum for a couple of hours and charged with the can upside down.

Don't over think this thing. AC is just a pumping system. Personally, I'd use envirosafe. Pressures are lower, pump will last longer and probably rob less horsepower, but that one is debatable.

Where do you live?

I'd go p-flow with 134.

As already state don't over think it. Key is good vacuum and a sealed system.

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Jim

With a P-flow, 134 is probably the way to go, but with an R4??? Good luck! I kept the old tube condenser with my new R4. I'm in hot west texas.


I'd jump on the pf condenser if they were priced on planet earth! I've never tried to flush one and always change them out. Not a problem when they are 60-70bucks. What Klima is getting for them is insane. If a PF condenser was used, I'd go sanden and 134a. Sure would be a shame to see an R4 poop up an expensive overpriced condenser!


Sprinkle chicken blood over the 3pointed star and hope for the best!
Piere in Orlando says to let the condenser be your guide which way to go.
If the condenser is good, keep it! If not, rip it all out and start over. I did all my own hoses and tig welding. It actually cost very little in parts.

I ended up getting an $80 P Flow condenser off of ebay made for W126 cars.
It has the correct top and bottom fittings, which is great, but they were in the wrong place!
Had to move the bottom fitting over about an inch and the top fittings were on backwards.
Also, the line going to the compressor comes out the bottom.
I didn't think it would fit because of the oil cooler, but it just clears it.
These are new builds and are still available.

Decided to go this route instead of the 40 year old tube and fin which had a
small leak in it. I am running R12 simply because I still have a few cans laying around.
The 350SDL cars came from the factory with a PF condenser and they were running R12.
I will be using a Rollguy Sanden kit. Rich said to go with the PF

Good Luck with your project
Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end