Charging a new A/C system

[1987 GMC Jimmy]

They come preoiled with PAG oil so I would just measure the difference for what the system calls for and add it. What I’m looking at says ten ounces for the whole system, and I’m assuming it came preoiled with three so add seven oz. of PAG 150 and then rotate the compressor by hand around ten rotations to move oil into the system. If you spill some, go ahead and add the extra ounce in your eight ounce bottle. As far as refrigerant goes, you need to get the pure R134a like they sell at O’Reillys in the 12 oz. cans, no oil, no leak sealer, no nothing. Three of those should get you to 80% of the original R12 capacity. Maybe get a fourth one in case some is lost in the process. Dye is always a good idea, but if you start having problems, you can always add it later. That’s what I’m gonna do anyway (fingers crossed for no problems). Dorman makes a line terminator kit to omit the rear A/C, but I’m not too sure about how that works. I imagine you’d just have to find the right one for your opening.

 

[CorvairGeek]

This is some awesome info guys, much appreciated!

My compressor is a new (not reman) Advance Auto brand (ToughOne) model that says it is pre-oiled. Should I drain it and add the total correct amount of oil, or leave it be and add a few ounces more based on the above recommendations?

What PAG oil should I be using? I was at the parts store looking at what they had, and there were several weights available.

Is R134 all created equal, or should I stick with some sort of brand? There seems to be huge price differences between store brand ($7.99 for 12oz) and other brands ($30+ for similar quantities).

Should I add a dye? If so, how much?

Last question, and this one is weird. I purchased all new hoses and lines, but the solid line I got that connects the evaporator to the condenser (that has the port on it) appears to be for a suburban. It has the extra connection on it just before the pressure port. Unfortunately this was the only replacement part I could find for this line. My question: can I cap off that connection, and if so - what would I use to do so? Does anyone have any experience capping off a Suburban rear A/C?

Hopefully, there are some exact instructions with the compressor regarding oil. Some of them can be kind of odd. My Chinese Delphi V5 (was supposed to have been a Delphi Korea unit) was loaded with oil. It said to drain the oil and put back the amount of the system volume specified, of the SAME oil that had just been drained. I wondered what may have been special (if anything) about the oil. There have been rumors of original oil viscosities that are slightly different from the OEM official recommendations (like the V5) and some aftermarket compressors will spec a different weight than what the OEM did. At a minimum, I would drain yours and put the correct volume in for piece of mind.

Domestic GMs are typically PAG 150 or 525 mineral oil (R12 only). I've been partial to;
https://www.amazon.com/ACDelco-15-1...ystem+PAG+Oil&qid=1559996399&s=gateway&sr=8-5
It claims 'Specially formulated for use in R4 and A6 compressors in R-134a refrigerant systems' I have no other evidence to support my like of it. PAG quality used to be all over the place at one time. However, if you new compressor suggests some other weight (GM sold the tooling off years ago), I would go with their instructions.

The cheapest, basic R134a is fine (or even best). Wal-Mart had it for under $5 for some time now (at least locally).

Jesse covered the other items, IIRC. Only a fraction of an ounce of dye is needed. I still get it everywhere, but it fades in time.

 

[da_raabi]

Again, thanks for the help guys.

I guess I'll send back the Suburban line. I can't figure out a good way to plug that port. The only issue with the old line was that I had cut in an inline filter. I pressurized it with air under water and there were no leaks so I think it should be ok. I did not have a black death situation, so again I think it'll be ok.

Next question: where is the a/c drain? I want to make sure it's clear before reinstallation but can't find it.

On a side note I have I'm working on fiberglassing the evaporator case back together. Stupid thing tore right in half when I tried to pull it out. I guess the exhaust heat must have gotten to it.

 

[da_raabi]

Ok, I repaired the evap box with some fiberglass and reinstalled it along with a new evaporator. Took a bit to figure out the tangs, but I think I got it. I also noticed that the tube coming out the bottom was bent to a goofy angle compared to the original, so I horsed it over to the right spot.

I took a look at the compressor and it said it has 5oz of PAG in it from the factory, should I add more? This compressor has been sitting around for a couple years, I hope its still OK.

I've got the ACDelco PAG linked above on the way.

I think I may finally get some A/C! It's about damn time!

 

[1987 GMC Jimmy]

If it hasn’t leaked any out, add five ounces. If you want to be safe, you can drain it and refill just so you know exactly. I’d let it sit for a while face down to make sure the seal gets some oil on it. Once you get it on, you’ll need to turn it by hand to push some of that oil around into the system. It should be fine. Unfortunately, it’s probably not under warranty now. Same thing here. I waited eleven months to install my A/C components and now I have a month of warranty left. I guess I oughta just use the **** out of it to make sure it’s okay.

 

[da_raabi]

Ok good idea on the oil. I may just change it to be sure.

As to the warranty - here is what is weird. The box and paperwork says it has a 2 year warranty, which would be over already. However, when I go to the Advance website and look up my original order, it says that the compressor has a lifetime warranty. I'm debating telling a little fib, saying it was seized in the box, and grab a fresh one. I really would hate to go through all the work to install everything just to find out the compressor was no good to begin with. I dunno.

 

[da_raabi]

So to be clear: In a brand new system, the total oil requirement in 10oz? With an A6 compressor, do I put it ALL in the compressor, or do I add some to other areas? I want to make sure I am clear on this part. I think I can handle getting the freon in and correct, but it seems the oil question is a bit ambiguous.

 

[CorvairGeek]

All goes in the compressor. Take the drain plug out and inject it into the hole with the compressor inverted. It is the crankcase of the compressor. I use a 2oz syringe myself. Takes 5 times on a big compressor like an A6.

 

[da_raabi]

All goes in the compressor. Take the drain plug out and inject it into the hole with the compressor inverted. It is the crankcase of the compressor. I use a 2oz syringe myself. Takes 5 times on a big compressor like an A6.

Ok, so stupid question time. I fill up the oil before installing the compressor, then still run the vacuum pump for an hour etc? It doesn't suck all the oil back out again?

 

[CorvairGeek]

Not a stupid question at all, and commonly misunderstood. Not enough air flow / CFM to move things around. Service ports are at higher points in the system.
Some fractional amount (0.xx%) will be lost (think vapor, and out gassing of moisture), but no, it will stay in place. Especially with a compressor with a sump.

 

[QBuff02]

What he said, kind of think of your system like a 4 stroke engine vs a 2 stroke engine. Since your compressor has a sump the oil is "in the pan" so to speak vs broadcast throughout the entire thing. And since the system is all new and hasn't ran before the amount of oil you'll lose is minimal at best.

 

[da_raabi]

Long story short: complete failure.

I tried to get the freon in it, but the low side pressure climbed crazy high (100+) and it stopped taking freon. I got maybe 16oz of freon in it. The bottom pipe on the evaporator iced up and the compressor and suction/discharge lines got super hot.

I have no idea what I did wrong. Then when I disconnected the gauges the low side valve started leaking.

Wonderful.

 

[1987 GMC Jimmy]

The old o-tube came out in one piece? And those low side adapters are junk. I’ve had them puke everything or the valves bend.

 

[da_raabi]

The old o-tube came out in one piece? And those low side adapters are junk. I’ve had them puke everything or the valves bend.

Brand new system, so the evaporator was new - no old o-tube. I used the o-tube I had in the old system. It was brand new and never run, it just sat there in the pipe for 3 years. Is it possible it's stuck or plugged? If I remember right, it was one of the auto-adjusting ones.

I'm going to try vacuuming the system back down then try it again. This could just be user error on my part. It was a long day installing all the parts and trying to get all the incorrectly-bent new tubing to fit right.

Now that the system has circulated a bit, should I put more oil in once I vacuum it down?

 

[CorvairGeek]

No more oil, but I did wonder if it possibly just needed more time to allow the refrigerant to enter. Not positive from your description that there was a problem yet (except for the low port issue, Jesse covered that). However, the variable orifice tubes don't have a good reputation.