CRiME

iTrader: (21)

What's up guys. Long time. Glad to see some of the old school guys are still around here.

I had a question about the AC in my '99. I bought this car in 2014 with no AC compressor. I bought a kit from RockAuto which included the compressor, expansion valve, drier and o-rings for $250. It sat in the box for 5 years, and I am finally ready to tackle this install. I've finally gotten around to fixing all of the issues with the car (did the VC gaskets, B pipe and muffler - that was a rust adventure in and of itself, but the search feature prepped me for all of that, and I bought replacement nuts and bolts before diving into that job - luckily).

Well anyway, my question is this. My new compressor came with PAG oil already loaded in the compressor. Thanks to Pmohr's videos, I'm going to tackle this myself. I have a manifold gauge set and vacuum pump and all of the stuff I need to vacuum and recharge the system. There should be no refrigerant in the system right now. I'm curious about the PAG oil, though. Once I've installed everything and vacuum out the air, what will that mean for the PAG oil that is pre loaded in the new compressor? Won't that be sucked out as well? I guess I'm just not too knowledgeable about the inner workings of the compressor. I'm just wondering if I should add more oil in addition to the new refrigerant. Can anyone in the know give me some guidance? It'd be much appreciated.

Thanks guys!

User1

Do not add oil if compressor came pre-loaded.

Turbobink

iTrader: (2)

It's all a question of PAG volume in the compressor as opposed to the required volume of PAG associated with your system.

Typically, a new compressor is drained in order to determine the from-the-manufacturer volume. That volume is then compared to the required system volume and the difference is what's still needed.

It's not common that a new compressor contains a volume of PAG matching or exceeding the volume required by an automotive AC system.

CRiME

iTrader: (21)

User1 and Turbobink, thank you for your replies!

This compressor has a sticker over it that reads "This compressor is filled with 6.5 oz of PAG 46 oil. Add 4 more ounces of PAG 46 oil for vehicles equipped with rear AC". We obviously do not have rear AC, so hopefully the 6.5 oz volume is sufficient for our cars - I will peruse the forums some more to double check. Thanks again guys! I'm going to do this over the weekend - I'll report back with an update as to how everything turned out.

KP11520

So what happens to the PAG oil in the compressor when you evacuate the system after everything is secured and sealed?

All my AC friends say ABSOLUTELY on evacuating first.

Hopefully your drier is still capped and that hasn't been touched.

I feel a Winter breeze coming soon! And better yet, a defroster that actually works when at 100% humidity and raining.

Turbobink

iTrader: (2)

Scroll to the very bottom of this page ... it provides some general PAG refill related guidance when replacing single system components.

https://www.aa1car.com/library/pagoil.htm

Check the sticker on the underside of your hood to determine the system's total PAG capacity and do the math from there.

User1

Lots of variables. I would suggest reading the HA section of your FSM and making your own, informed decision. You know the history the best. I replaced every single component in my 5th gen AC system with new components and a brand new, pre-filled Denso 7th gen Maxima compressor and added no oil. I vented a few pounds while tuning the system the other day after driving it a couple days and nice, new, clear oil immediately came out of the discharge hose. I'm solid.

You bought with no compressor. Your system has been sitting exposed, but has oil in the coils. If I were you, I'd change receiver/drier, button up the system with the new compressor, pull a good vacuum and charge it.

KP11520

Tb, so like he's asking, add the right amount or proper PAG oil as if none were in the compressor after evacuation?

Turbobink

iTrader: (2)

Typically, with system evacuation, very little if any PAG is removed ... only/mostly refrigerant. PAG removal is called system flushing.

It's a safe(er) assumption that the generally accepted volumes of PAG remain in each component, even after evacuation.

In CRiME's situation, the evaporator and condenser haven't been replaced ... only the compressor and accumulator are new.

If this were me and if I was not replacing all components, I'd assume that the accepted volumes of PAG remain in the old/remaining evaporator and condenser; I'd know what the total system PAG volume is; I'd drain the new compressor and; I'd take my car to a local shop and tell them to recharge the system and add "X" amount of PAG 46 to equal the system's specified PAG volume.

But that's just me ...

KP11520

WOW!

Thank you for quite a bit of illumination and clarity of lingering gray definitions! Scary how many let that ambiguous uncertainty persist.

And NO.... That's not just you! I agree on KISS.

User1

CRiME is charging in his driveway and has no old compressor to compare volumes. Sorry if I'm too short with my simple, practical responses. Thankfully, there are members like Turbo to add theory to enlighten the more curious minds in the forum. CRiME's situation remains the same, and more importantly may need to remove oil vs add oil. Again, he has no old compressor.

Depending on your source, I would recommend researching exactly what is included with your compressor. Here is the documentation for the unit I purchased for my brand-new, bone dry system:

https://www.rockauto.com/en/moreinfo...=3305933&jsn=8

Note "Compressor; w/ Clutch; OE-specified Oil included"

http://densoautoparts.com/find-my-pa...#searchResults

Note in the installation instructions that you are referred to the FSM for your vehicle, and that the instructions in both the FSM and DENSO manual cover replacement procedure of a used unit only using professional recovery equipment, you have to do the math to install brand new and in situations like his with an incomplete system.

Here's my best attempt at a proper, step-by-step for CRiME:

1) Read "Service Data and Specifications" page under HA section in the FSM for TOTAL SYSTEM VOLUME

2) Read "Lubricant Adjusting Procedure for Components" table in HA section for individual component volumes (we're talking 2.5ml for condenser, evaporator, etc., very small amounts).

3) Drain new compressor into container following the drain procedure for your unit (my DENSO unit requires rotation of the clutch plate 10 times to free oil from the head)

4) Subtract total coil volumes from container, add accumulator volume to container, then ensure total volume in container equals total system volume indicated in "Service Data and Specifications"

5) Refill compressor and install


OR, bolt the damn thing on, pull a deep vacuum for a while and charge it up. I would be comfortable with either method.

CRiME

iTrader: (21)

Wow, thank you all for taking the time to advise me, and for the excellent discussion. This thread will certainly prove useful both to me and to anyone else who may pull it up in the search years down the line. User1 is correct - this will indeed be a driveway job and, prior to making this thread, I was actually leaning toward his latter directive of bolt on, vacuum and charge.

I'm going to check the sticker beneath the hood, do some quick math and proceed from there. I was just trying to get a mental picture of how this all works. I was asking myself why the manufacturers would pre-load the PAG oil knowing that the system had to be vacuumed upon reassembly. Now that I've learned that the vacuum typically will not remove the PAG oil, I have a better understanding of what is going on.

maxima.org comes through yet again - that's why this place will always be my home! I'm really looking forward to this job. I am also going to replace the blower motor resistor while I have the glove box out, and then I have to do the ignition switch. This car is finally beginning to shape up. I may even have to put away the Lexus for a bit once I complete all of the projects that I have in line for it. Will report back with an update over the weekend. Thanks again guys!

reallywildstuff

sorry to be weighing in so late on this:

before putting in the time and expense of installing that new compressor: i would be wary of foreign contaminants (as from a failed compressor) remaining in the lines/condensor/evaporator absent a flush

the only way to remove those foreign bits would be the "flush" that was previously mentioned - however, that would also remove the total amount of oil in the system (which is where the contaminants are hiding)


this kind of horsieness is why professional A/C service is a good line of work to be in

CRiME

iTrader: (21)

Thanks, realywildstuff. In my reading I did learn of that possibility. As per the previous owner, the compressor was still functioning but just noisy. I remember I had this problem on my '95, and I believe it was caused from water repeatedly contacting the unit - I had no splash shield on that side. I got around it by bypassing it with a shorter belt. At any rate, I will keep your post in mind. Thank you.

maxprivate

iTrader: (12)

Absolutely not. You don’t need to add any oil and there will be some oil in the refrigerant when you charge the system. Pull a good vacuum with a Micron gauge to 500 microns. This will ensure all the moisture is out of the system. ( do this first) Replace the filter drier, pressure test, then vacuum. Lastly, Then weigh in the manufacture charge of gas. You can find that info on the label under the hood or I’m sure you can look that up.

Dont over think this.. it’s not that difficult and certainly not “rocket science”.

CRiME

iTrader: (21)

Finished the AC job this evening. I had replaced the expansion valve and blower motor resistor last night, and picked up the job again this afternoon. The AC is ice cold! I decided to check the oil level in the new compressor prior to installation, and it is a good thing that I did. Even after turning the clutch, there was NO oil in the compressor - apparently it all leaked out over the 5 years I had it sitting in the box. There was a stain / residue on the box, but I wasn't certain as to what it was. Looks like it was the oil.

I added the correct amount as per the sticker, using a kitchen scale to check volume. Bolted it in, installed a new belt, changed the dryer. I vacuumed the system, switched off the vacuum and it held steady at -30, so I started the car, attached the can, bled the line and proceeded to add the refrigerant. I expected the compressor to switch on, and it didn't. I started to worry that my compressor was a dud. Luckily, I cracked open the fuse panel and found the 7.5a AC fuse blown. Replaced it and the compressor sprang to life. Added the rest of the refrigerant and everything worked out perfectly.

Thanks again for the discussion in this thread. Prior to posting here, I was going to just bolt it up, assuming that enough oil was loaded and good to go. You guys may have saved me from a compressor disaster. maxima.org FTW!

User1

A 5 year old oil soaked compressor box, yeah, might wanna check that one. Fresh compressor just delivered by the friendly UPS guy today, not worried about it.

Nice work.

What is your vent temp with windows down and what are the ambient conditions?

Edit: Forgot to add, why did the oil leak out of the compressor? You didn't just install a bad compressor, did you?

CRiME

iTrader: (21)

Thanks, User1. I'm not really sure as to why it . The box was stashed away over the years and may have actually been upside down. Although the unit shipped with a plastic cap covering the low and high pressure ports, I did notice a small oil stain on the compressor in a crevice near to the openings.. After I loaded the new oil, I didn't notice any leaks or abnormalities. Everything is great for now, but I will still keep an eye on it. I couldn't find my thermometer, but I'm going to pick one up this week and check the temperatures.

User1

Yeah, they come capped, so strange that it leaked out?

Vent temp and pressures???? Don't hold out on us!

maxprivate

iTrader: (12)

Up side down box could do it. Usually they seal with plastic caps or the copper lines are brazed closed.

Im not an Auto Mechanic so not sure how it is with Air conditioning in a vehicle but for residential, that’s usually how a new compressor is sealed, as mentioned above.

The traces of fluid leaking on the box was a give away. Good thing you indeed checked that. Good work.