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A/C System Oil

Started by Dan LeBlanc, June 23, 2020, 03:40:03 PM

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Dan LeBlanc

I feel like I've asked this question before when I got the 77, but I can't find the post.

Is there a way to determine what type of oil is in your a/c system if you don't know what a shop used when they had the system open?  I called the shop that did the work prior to my ownership of the car, they have no record of what was actually used after replacing the evaporator and flushing the system before recharge.

The a/c is working as well as can be expected for something running Freeze 12.  Personally, I don't like Freeze 12 as it tends to fall flat on its nose compared with R12 but it is what it is right now.

If I could determine I had mineral or Ester in there, then I would evacuate and recharge with R12, but without knowing what's in there for oil, I'm not willing to take the risk, especially since it is working.  Yesterday, it was 85 and humid here, vent temps were around 58F.  I did notice the aspirator outlet on the programmer was plugged with some crud and the blend door was not going to full cold.  Cleaned that, adjusted the blend door so that I hit full cold at 65 and now I'm down to 48F, but I want to get into the 30s!

Maybe I just have too much time (and R12 waiting to be used) on my hands.
Dan LeBlanc
1977 Lincoln Continental Town Car

scotth3886

#1
Quote from: Dan LeBlanc on June 23, 2020, 03:40:03 PM
I feel like I've asked this question before when I got the 77, but I can't find the post.

Is there a way to determine what type of oil is in your a/c system if you don't know what a shop used when they had the system open?  I called the shop that did the work prior to my ownership of the car, they have no record of what was actually used after replacing the evaporator and flushing the system before recharge.

The a/c is working as well as can be expected for something running Freeze 12.  Personally, I don't like Freeze 12 as it tends to fall flat on its nose compared with R12 but it is what it is right now.

If I could determine I had mineral or Ester in there, then I would evacuate and recharge with R12, but without knowing what's in there for oil, I'm not willing to take the risk, especially since it is working.  Yesterday, it was 85 and humid here, vent temps were around 58F.  I did notice the aspirator outlet on the programmer was plugged with some crud and the blend door was not going to full cold.  Cleaned that, adjusted the blend door so that I hit full cold at 65 and now I'm down to 48F, but I want to get into the 30s!

Maybe I just have too much time (and R12 waiting to be used) on my hands.

Great question and the one that I was going to ask next.  My 66 is a conversion from R12, which I much prefer, to R134 when I bought it a couple of months ago. 

If I can't get this blend door situation fixed, where it won't shut off the floor vents entirely and give me some more air flow volume, I'm definitely going to convert 'back' to R12.   Why on earth the former owner did this given that he lived in Scottsdale is beyond me.  Last Saturday was near 90 when I left Cars and Coffee and just couldn't get it cool enough that I could get blower fan speed off of high. 

I get mid 50s vent temps on my Fleetwood and the 63 GP sitting right next to it will go down to high 30s.  My 66 GP also has Comfortron and it gets to high 30s, but of course its R12.

Heading out to the garage now to try some tips that Tim Grove provided this morning.

"Cadillac Kid" Greg Surfas 15364

Dan,
The best way to start this reply is with the fact that Freeze 12 is a Hydrocarbon refrigerant (Propane/IsoButane) and as such reacts with the components of R-12 systems (oil, hoses, bronze and brass_ differently than the original Mineral oil.  That said regardless of which oil your system contains the Freeze 12 has changed its composition. If you are going to go back to R-12 a thorough disassembly and cleaning of all the system components to remove ALL oil.  This is a timely and expensive process but it will prevent system and component failures due to contaminated oil plugging up orifices and not circulating for compressor lubrication as needed.
This is essentially the same process required as those going back from 134a to 12 have to do.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Dan LeBlanc

Johnson's Freeze 12 is actually 80% R134A and 20% R142B according to the MSDS. That's what's in there, not one of the hydrocarbon (propane based) refrigerants. If I'm understanding the difference between HCFC and hydrocarbon refrigerants correctly. I've been wrong before though.
Dan LeBlanc
1977 Lincoln Continental Town Car

fishnjim

It can be sampled and analyzed.     
If it's R134a based, it's likely a PAG.   But no way to tell from here.   
Best thing is to check with the original refrigerant manufacturer's recommendation, which mostly likely the garage used, if reputable.   Probably supplied oil when they bought the refrigerant.   Maybe contact the manufacturer's tech service.   They can also tell you if you can get to those numbers, or if you're chasing tail.     
There are some after market test kits to check the oil "condition", but have no experience or if there's a typifier kind.   U can search.

I remember when we introduced 134a, they had trouble in some of the large compressors and the oil was changed and it resolved.  So important to use the right stuff.  But can't recall the details 30+years after. 

Mike Josephic CLC #3877

Just to add some additional confusion at this point.

Be aware that "PAG" oil is not one product -- there
are several different types that were used in automobile
systems.  The viscosity varies according to what type
of compressor is in the system.  This short article
explains that nicely.  The 3 major types are:  PAG 46,
PAG 100 and PAG 150.

https://www.underhoodservice.com/ac-compressor-oils-types-uses-differences/

Mike
1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

"Cadillac Kid" Greg Surfas 15364

Dan,
I erred in listing Propane and Isobutane as ingredients in Freeze 12, but the Hydro Carbon (abeit CloroFlourinated ) components as they present themselves in any residual oil will make a "witches brew" out of R-12 and Mineral oil.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Dan LeBlanc

Given that the refrigerant is mostly R134a, it's safe to say that the numbers I'm seeing out of the vents are pretty normal.  At this point, I'll just leave it until something happens (if it happens) and call it a day.  I was hoping for a non-invasive test measure to determine oil type, evacuate, and recharge, but it appears as if that's not the case.
Dan LeBlanc
1977 Lincoln Continental Town Car