Adding PAG oil after A/C repair

[fastpakr]

Hoping somebody can clarify a few points now that I'm done reassembling the A/C system in my Ranger with the engine swap...

The old 5.0 compressor was locked up tight (looked like the pulley bearing died). I purchased a new compressor, orifice tube, accumulator, and condenser. Both hoses have been sprayed out with brake cleaner, blown out with compressed air, and o-rings have been replaced. After reassembly, I hooked up the vacuum pump and gauge set last night and vacuumed things out for about an hour, then left the gauges hooked up. As of this morning, the system seemed to be holding a steady vacuum.

Now it's time to deal with charging it back up. I know the entire system holds 9 ounces of oil, and there will be a label on the compressor indicating how much it was shipped with. Assuming the evaporator hasn't been drained of its own oil, I need to account for an empty accumulator, condenser, and the two hoses. Does 4 ounces of oil seem like a reasonable quantity?

Next question - where and how is the best way to add that? I'm assuming I can just equalize the pressure by pressing the low side shrader valve fitting. Can I just remove the valve core with a tool and carefully pour that much oil in, then reseat the core and vacuum the system down before adding freon?

 

[Denisefwd93]

it's actually very easy to add oil while you have the vacuum on the system.

but first question is, did you replace the accumulator? if not, did you take the old accumulator out and dump the oil out of it?

Did the new compressor or come with oil in it? I'm under the impression that they do. If it did not, you need to know how much. There should be instructions on how to add oil to the compressor, before it is on the truck.

To add oil to a system that is under a vacuum. Put the yellow charging hose in a container of PAG Oil, 0pen low side valve on guage manifold slightly. the vacuum will draw the oil up the hose into the accumulator, just don't let the end of the hose suck air or you'll be pulling in vacuum all over again. You can also buy containers of oil that I already have pressure and refrigerant in them.

no way to know how much oil to add until you know how much will you have, and how much is required by the new compressor hope this helps.

 

[fastpakr]

I did replace the accumulator, meant to say that earlier. The new compressor did come with oil, and I'll verify how much this evening when I get home.

no way to know how much oil to add until you know how much will you have, and how much is required by the new compressor hope this helps.

I'm not entirely following that - assuming I determine the new compressor came with x ounces of oil, and knowing the total capacity is 9 ounces, there has to be a way to estimate how much to add by guessing how much is in the evaporator, right?

Thanks for your help.

 

[Denisefwd93]

The oil in the system is only for the compressor any oil in the other parts migrates to and from the compressor.

You did replace orifice I hope?

One of the troubles with automotive air conditioning is keeping the oil in the compressor where it needs to be,. Because it is higher than everything else in the system usually

 

[fastpakr]

Yes - the orifice tube is new as well. For what it's worth, on the Explorer V8, the compressor is pretty low. It's mounted below the power steering pump on the passenger side, so it's basically the lowest point in the system.

 

[Denisefwd93]

That's a good thing! I would say it is a design consideration more than about service,. the oil will migrate to the compressor when it's running. I think you're safe as long as you don't have a gross amount of oil in there,. I mean it is possible to fill the accumulator with oil and still have the system running!

 

[85_Ranger4x4]

Yes - the orifice tube is new as well. For what it's worth, on the Explorer V8, the compressor is pretty low. It's mounted below the power steering pump on the passenger side, so it's basically the lowest point in the system.

Neither here nor there really but it is on the drivers side.

 

[fastpakr]

Your truck didn't come from England like mine?

Just kidding. Not sure how I screwed that up earlier. It's not like I just finished putting everything in there or anything...

Sent from my SM-G960U using Tapatalk

 

[Denisefwd93]

OMG, the old gm DA6 was down low and close to the cat on my 2.8 gm v6 Pontiacs,

 

[85_Ranger4x4]

Your truck didn't come from England like mine?

For better or worse mine is from Kentucky...

 

[adsm08]

Neither here nor there really but it is on the drivers side.

Actually, that is here and there.


Anyway, I would put about 2 oz of oil in. Ford systems don't like to be starved, but are generally designed to be able to handle up to one full over-charge worth of oil. So if your system is spec'd to take 9 oz, you can get away with up to 18 without doing damage.

It is still better to have the right amount in, but you can be ok with more.

 

[fastpakr]

Thanks for that info. Also just to confirm - the oil doesn't come out during vacuuming, just air and moisture, right?

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[adsm08]

Some oil comes out. If you use a real proper AC machine it will separate the oil it pulled out with the refrigerant and you can see how much came oil through a little sight glass on the machine.

That amount is usually 1 to 2 oz, which is where I got that number.

 

[4x4junkie]

If there wasn't any refrigerant in it before you pulled the vacuum, then whatever amount of oil was in there shouldn't change.

Just in playing it safe, I've always dumped out whatever oil that comes in a new or rebuilt compressor (also flushing out both the evap and condenser, hoses, etc. too) and started afresh with new oil of the required amount & spec for the truck (PAG-46 for new/rebuilt FS6 & FS10 compressors w/R-134a). Unless it happens to be stated on the box, there's no way to know what oil is in there (could be PAG of any viscosity or ester). This way I know I have both the right amount of, and right kind of oil.

Also, I wouldn't suggest the method described earlier for using the vacuum to pull oil in unless the system is currently being vacuumed at the same time. Reason being, whatever air is contained within the hose itself will also be sucked into your system (maybe if you filled the hose first with oil, then submerge the end and draw it in would be OK, but if you got a vac pump, seems easier to just do it while you're vacuuming).

 

[Denisefwd93]

4x4 good to see someone was aware of this!
" Reason being, whatever air is contained within the hose itself will also be sucked into your system"

It can be done if you have a dual hose valve setup.

DIY on Automotive Systems, it's easier to get the oil in a pressurized can.

It's been getting chilly in my truck lately!!