Adding PAG oil in Old A/C system with no new parts

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GreyWisent

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I had to evacuate and open my A/C system because I needed to replace my heater core. How much PAG oil do I need to add if I'm not changing any of the parts?

I didn't do my homework properly (just read the removal instructions) and didn't know I had to measure the amount of oil I take out of the system. The mechanic who did it for me didn't mention it either, even though we talked for a good half hour.

My A/C system was working flawlessly (or at least I didn't have any issues) before. I'll be changing the O-rings in the expansion valve (TXV), and that's the closest instruction I found in the manual. Also, do I need to lubricate the new O-rings in the TXV?
O-ring Leak Repair - 60 ml (2 fl oz.) added to the amount collected during refrigerant recovery
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Is there a rule of thumb as to how much I can safely assume was lost during recovery (and over the years)? Should I just got with 2oz and assume no loss? If it makes a difference, I drove the car for about 10 minutes with the A/C on before I evacuated the system; the mechanic only tapped the valve at the top of the drier for evacuation.

I read a bunch of threads here and it seems like the only downside of too much PAG is loss of cooling capacity. Vs "compressor explosion" when there's too little, it seems like I'd want to err on the safe side.

Lastly, oil is added when refrigerant is added, correct? In other words, you evacuate the line to -30 in-Hg and add the oil just before adding refrigerant, right? PAG-46?
 
Usually, very little oil comes out when you discharge the system. I think I've seen an ounce at the most. However, like you said too much is better than too little, so I think that adding 2 ounces is a good plan.

Yes, you want to lubricate any o-rings that you replace, and you want to replace any o-rings that you disturb.

No, generally oil is added before sealing up and evacuating the system. Pulling a vacuum does not remove any oil. Usually, it's added by pouring it into the compressor before installing the compressor. Then you have rotate the compressor (inner part of clutch) several times to distribute the oil in the compressor. Since you don't need to remove the compressor, the easiest way to add the oil is to pour it into the receiver dryer. Speaking of which, you do know that you really want to replace the receiver/dryer, right? It's probably saturated now after being there so long and opening the system was possibly the last insult for it. You'll need new o-rings, and you'll have to drill a hole in the bottom of the old one and measure how much oil comes out. Add that much more new oil to the two ounces you already planned on.
 
I just changed my compressor and receiver/dryer and the new receiver/dryer arrived with two new O-rings already in the recesses.
 
I just followed what the service manual stated per part, although I probably put an extra amount in.

Replaced the compressor; it already had some in from the manufacturer, I added to bring it up to Lincoln's stated amount per their instructions.

The condenser, what Lincoln stated when replacing.

The R/D, drilled hole it had none come out, so I fudged by taking the full total amount in the spec's, minus the compressors amount, minus the condensers amount, and minus what the service manual said to add to the evaporator if I had replaced that.

Thread: Successful AC rework.
 
Thanks everyone for confirming my suspicions.
joegr said:
Speaking of which, you do know that you really want to replace the receiver/dryer, right? It's probably saturated now after being there so long and opening the system was possibly the last insult for it.
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I knew close to nothing about A/C systems before I started removing my dash, but I've been learning a lot. All my previous cars had no working A/C when I bought them and I just didn't bother since I don't use my car daily AND I live in a cold climate. Thanks for pointing the necessary dryer replacement out, Joe! I missed that detail and it made me realise that I need to educate myself even more. It makes even more sense seeing how cheap they are and that it's a pretty easy job. The manual is quite clear on how to do it, but thank you for taking the time to write it up and confirm it. I have to say, drilling a hole in the dryer seemed quite suspect when reading about it in the manual.

I've been thinking of getting an aftermarket dryer though. Any thoughts or recommendations on that? Joe, I read that a while back you re-did your entire A/C system with a cheap import kit. You mentioned that the compressor failed within a month (but you were able to rectify that with changing one of the seals). How about everything else? Are you happy with it? Otherwise can anyone recommend (or what to avoid) any brands for the dryer? I'm leaning on the Four Seasons one from Rock Auto. I was not at all impressed with how my Spectra Premium heater core looked and the manufacturing sloppiness and will probably avoid t hem in the future.


milehighmikey said:
I just changed my compressor and receiver/dryer and the new receiver/dryer arrived with two new O-rings already in the recesses.
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Thanks! I bought a full A/C O-ring kit figuring out I'd use it sooner or later. The dryers all look like they come with new O-rings, but it's always good to get live confirmation.

TooManyToys said:
Replaced the compressor; it already had some in from the manufacturer, I added to bring it up to Lincoln's stated amount per their instructions.
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The PAG oil addition instructions for replacing A/C system parts are pretty straightforward. Already had read through all of that. Just didn't see much about adding oil when opening and not replacing anything. That's great information though.


Bonus question: WHY do we need to lubricate O-rings when replacing them? Is it for ease of installation or for making them last longer - and why does it happen?
 
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Lube O-rings: Enhances the seal

Be careful with O-ring kits: Our LS uses thicker O-rings than many kits contain and the thinner O-rings will not seal our system. You will see what I mean when you receive your receiver dryer.
 
I'm okay with aftermarket dryers. I don't know which are better or worse. I would stick to OEM for the expansion valve and evaporator, just due to the difficulty of replacing them.

Always lubricate o-ring seals. This this true for any system (cooling, AC, engine lubrication, ...). Just use whatever the seal normally experiences for lubrication. Compressor oil for the AC, coolant for the cooling system, oil for the engine oil, ...
You lubricate the o-ring so that it won't twist or fail to seat correctly.
 
I can second the O-ring kits. They’re not Lincoln compatible really. 1 $10 kit gave me two useable seals in my system overhaul. Little did I know, the the condenser, compressor and THX came with rings.

I had a similar issue with Spectra heater core I bought since I figured “might as well”. Fitment was horrible so I just put back in the old one.

I have a Four seasons compressor and drier since late May - no issues.

Since you have it apart, might as well replace the THX valve if you plan on keeping the vehicle. Definitely go Motorcraft on all the interior stuff, as Joe said, fitment and quality is good and you don’t want to tear everything back out in a year.
 
Also, who is charging the system? You or mechanic?

Just because you need to keep in mind most A/C canisters you get from stores (if not all) have oil in them. Every can I found had between 1 - 2 oz of oil. So you need to figure that in as well.

Not sure if it’s to help as a carrier or what,but my system is slightly overfilled since I lost about 2oz putting in the compressor and gained 4 oz on charging. But I still drop into mid 40s which is plenty cool
 
You can find cans that are just R-134a at Walmart and Sams. (Better price at Sams). Besides the oil, those other cans add other crap too. Anything that isn't refrigerant is not helping you.

If you are self charging, you must pull a really good vacuum for about a half hour before adding refrigerant. This is to boil the water out.
 
Broseph said:
I can second the O-ring kits. They’re not Lincoln compatible really. 1 $10 kit gave me two useable seals in my system overhaul.
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Great... At least now I know not to count on that O-ring kit. I got the 4 Seasons one 41-piece one for about $10. Thanks for the warning.

Broseph said:
I had a similar issue with Spectra heater core I bought since I figured “might as well”. Fitment was horrible so I just put back in the old one.
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Ugh. Not looking forward to this... It already looks very crooked, just by eye, and even in the product images. Twisting and forcing that tiny radiator is likely to make it fail faster. Motorcraft is 4x the price, but just factoring in the A/C service in changing the core again adds up to that difference. Should have "splurged", but we'll see. No time to change it now - need my car back on the road soon and can't afford to wait for another core to be shipped in.

Broseph said:
I have a Four seasons compressor and drier since late May - no issues.
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Good to know! I'll buy that one. Although 3 months is not long enough.

Broseph said:
Since you have it apart, might as well replace the THX valve if you plan on keeping the vehicle. Definitely go Motorcraft on all the interior stuff, as Joe said, fitment and quality is good and you don’t want to tear everything back out in a year.
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Should have done that, but I cheaped out on the $60. They don't seem to be a common failure point, so hopefully I'll be fine. I'm a bit more annoyed that I didn't change the evaporator, but now that I think about it, I don't want to spend another $150 for a Motorcraft one - I imagine the fitment issues are the same as the heater core, but they matter more here.

Broseph said:
Also, who is charging the system? You or mechanic?
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I found a retired guy who opened a mobile shop and specialises in this. Was going to use him, but then I found out that someone in my extended family has a vacuum pump and the gauge manifold, so he's going to help me out.

Broseph said:
Just because you need to keep in mind most A/C canisters you get from stores (if not all) have oil in them. Every can I found had between 1 - 2 oz of oil. So you need to figure that in as well.
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Any particular brands I should avoid? Most of the ones I've seen have any additives listed on them. I'm looking at either DuPont Suva, Weitron or Johnsen. Not too concerned though. Don't need to get my A/C down to 40 degrees. Just as long as it works and last me another summer or 2.

joegr said:
You can find cans that are just R-134a at Walmart and Sams. (Better price at Sams). Besides the oil, those other cans add other crap too. Anything that isn't refrigerant is not helping you.
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This is a problem for me... I can't source R-134a locally. Here, in Canada, you're not allowed to sell it to someone that's not licensed. So I'll probably have to buy it online at a ridiculous price, or look at classifies. If I don't cross the border, I'm looking at USD $50-60 minimum... In which case, that mechanic might make more sense, for $20 more in labour.
 
GreyWisent said:
... I can't source R-134a locally. Here, in Canada, you're not allowed to sell it to someone that's not licensed...
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Do stay away from R-12a (propane, more or less). Don't let its claim to replace R-134a fool you.
 
joegr said:
Do stay away from R-12a (propane, more or less). Don't let its claim to replace R-134a fool you.
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Yeah, that junk is the devil! I don't know how they're allowed to sell it in top-up kits when you're not supposed to mix it with R-134a. Not to mention it's overpriced by a factor of 100x, for just being propane and isobutane.
 
joegr said:
You can find cans that are just R-134a at Walmart and Sams. (Better price at Sams). Besides the oil, those other cans add other crap too. Anything that isn't refrigerant is not helping you.

If you are self charging, you must pull a really good vacuum for about a half hour before adding refrigerant. This is to boil the water out.
Click to expand...

I actually had to stop in Walmart and just found one finally. Supertech appears to have just refrigerant even if it appears to be off-brand. Ez chill and A/C pro both carry oil and additives
 
GreyWisent said:
Great... At least now I know not to count on that O-ring kit. I got the 4 Seasons one 41-piece one for about $10. Thanks for the warning.

Ugh. Not looking forward to this... It already looks very crooked, just by eye, and even in the product images. Twisting and forcing that tiny radiator is likely to make it fail faster. Motorcraft is 4x the price, but just factoring in the A/C service in changing the core again adds up to that difference. Should have "splurged", but we'll see. No time to change it now - need my car back on the road soon and can't afford to wait for another core to be shipped in.


Good to know! I'll buy that one. Although 3 months is not long enough.


Should have done that, but I cheaped out on the $60. They don't seem to be a common failure point, so hopefully I'll be fine. I'm a bit more annoyed that I didn't change the evaporator, but now that I think about it, I don't want to spend another $150 for a Motorcraft one - I imagine the fitment issues are the same as the heater core, but they matter more here.

I found a retired guy who opened a mobile shop and specialises in this. Was going to use him, but then I found out that someone in my extended family has a vacuum pump and the gauge manifold, so he's going to help me out.

Any particular brands I should avoid? Most of the ones I've seen have any additives listed on them. I'm looking at either DuPont Suva, Weitron or Johnsen. Not too concerned though. Don't need to get my A/C down to 40 degrees. Just as long as it works and last me another summer or 2.


This is a problem for me... I can't source R-134a locally. Here, in Canada, you're not allowed to sell it to someone that's not licensed. So I'll probably have to buy it online at a ridiculous price, or look at classifies. If I don't cross the border, I'm looking at USD $50-60 minimum... In which case, that mechanic might make more sense, for $20 more in labour.
Click to expand...

Sorry I didn’t warn you sooner. I’m not on too often anymore. My spectra is still sitting in my home office because Rockauto won’t accept returns on installed parts.

Side note: Rockauto no longer has customer service. It’s all automated online with 40 questions. Do NOT say your part was installed like I did (was only for a few minutes when I realized it wouldn’t do) and they won’t take back the $70 heater core that is completely misaligned like you noted.

As long as the mechanic does a proper install, vac and fill, four seasons isn’t bad. I think the next option up was motorcraft at a few hundred more.

My THX was bad and promoted the dash removal. Note that Ford suggests replacing the THX every time the system is worked on (No one does this) and you’ll probably be fine with the old or off brand.

Good luck with everything
 
I bought the "Lincoln LS" o-ring kit since Ford discontinued some of the o-rings. Total waste of money.

Straight R134 is not hard to find in the cans, NAPA, Advance, RockAuto ...... just get a known brand name.
 
Broseph said:
...My THX was bad and promoted the dash removal. Note that Ford suggests replacing the THX every time the system is worked on (No one does this) and you’ll probably be fine with the old or off brand...
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Confused me for a moment...

It's TXV, not THX. Two very different things.
 
TooManyToys said:
Straight R134 is not hard to find in the cans, NAPA, Advance, RockAuto ...... just get a known brand name.
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Can't find any refrigerant on RockAuto, but they have all the other fluids: oil, system flush, core cleaner. Can you point to where you found the refrigerant? I wonder if they have an IP filter for Canada, blocking that product - they already auto-detect CAD$ based on IP.
 
joegr said:
This is probably true of all the big guys. Did you try ebay? Maybe a seller there would be willing to ship to Canada.
www.ebay.com/itm/3-Cans-R-134a-DuPont-Suva-A-C-Automotive-Refrigerant-Freon-R134a-12oz-Cans/282519030011?epid=1417800503&hash=item41c77248fb:g:BYEAAOSwv0tVGobY
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That one doesn't ship here, but there are a couple that do ($40 shipping though). Amazon has some options too, but also expensive shipping.
It's more of a matter of economics though: if it comes out to the same price as paying a tech to do it, I might as well go with that option.

It's actually really annoying because "by law, the removal, discharge, handling and disposal of refrigerants that contain ozone depleting substances and other hydrocarbons such as CFCs, HCFCs or HFCs must be performed by a certified technician" (looking at HFCs here), but I'm not removing anything, only adding. I guess that must count as handling? :|
Whatever; it's better this way, IMO. For every responsible person there's 100 idiots who don't bother to do things right.

Anyway, thank you everyone for taking the time to help.
 
No ozone depletion with R-134a, it's just that it is a greenhouse gas. (Still, it's okay to use those air duster cans that have pretty much the same thing in them.)
 
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