FR12 vs R12 Charge size.

[Ralph Messina CLC 4937]

I’m converting my ’66 Cadillac AC system from Freon (R12) to Freeze 12  (FR12).  â€" ( Thank you to Greg Surfas for the help unravelling an abortive attempt to convert to R134.)  - The Shop Manual indicates the Freon R12 charge should be 4 pounds. Searching the web I’ve found blogs indicating the FR12 charge should be both 10% less and 10% more than R12. I’d appreciate comments from anyone with experience or knowledge about the correct charge size.

Thanks,
Ralph

[76eldo]

My mechanic says it's a direct replacement.

Hope that helps.

Brian

[Scot Minesinger]

If FR12 is short for freeze 12, it is 80% r134 and 20% r142.  If you convert, probably best to take same steps as r134 conversion: 

1.  Remove ALL original mineral oil (flush entire system)
2.  Replace hoses with barrier type.

I worked on two Freeze 12 converted cars and both suffered plugged condensers (maybe decomposed hose and r134 sludge making with mineral oil).

[Ralph Messina CLC 4937]

Scott,

Thanks.
I received information that FR12 needs to be run with mineral oil. Can you suggest a datasheet source of information. The brand is Johnsen's but I haven't had the time to research or contact them.

[RobW]

Why would anyone use freeze12? Like Scott said it's mostly 134 anyway so just use that if you don't want 12. Another thing is it's not made anymore and those that have it think it should be priced like real R12. And there is no such thing as a "direct" replacement.

["Cadillac Kid" Greg Surfas 15364]

You know it is amazing how if a "miss statement" is repeated often enough it becomes the truth.
FR-12 is not 134a and anything else.  It is;
15-40% Methylethymethane
30-60% Methylpropane
40-70% dimethylmethane.
Yes, the percentages vary, and that is in accordance with how they choose to blend each batch.  That way they disclose the components as the must for the MSD's, but keep the formula "secret".

Another misnomer is the lubricant.  It also contains a stabilizer and is miscible with Mineral oil, the only type of oil re3commended.
Just could not sit by and watch this mis information continue.
Sorry
Greg Surfas

[76eldo]

All I can tell you is that my mechanic used it for years to keep old r12 customers cool. I used it too and never had a problem

Brian

[RobW]

OK FR12 IS NOT Freeze 12 as the OP stated above. Freeze 12 was mostly R 134a as Scott mentioned and is no longer made.

[RobW]

straight from the Airgas website...
FR-12 Versus R-134a
FR-12 has lower high and low-side pressures
FR-12 is designed to replace R-12
FR-12 is an enhanced R-134a blend
FR-12 is compatible with the existing oil in R-12 systems
FR-12 produces a faster interior cool down
FR-12 is less susceptible to system shut-down under hot idle conditions
FR-12 system runs at lower temperatures and pressures, extending compressor and system life expectancy
FR-12 system has less system leakage because of lower pressure
No Change in Lubricant

[RobW]

you might want to read this before adding to the "mis-information"
http://airgasrefrigerants.com/fr-12.php

[Ralph Messina CLC 4937]

Guys,

Thank you for your input.  I had trouble finding the MSDS sheets but eventually found them. Freeze 12 was manufactured by Technical Chemical Company of Cleburne TX. It is not produced any longer and should not be confused with newer "Freeze" products. Apologies if the short hand "FR12" caused confusion.

The reason I’m using Freeze12 as the refrigerant is that nothing - I mean nothing - we’ve done with the R134 conversion would work. About 15 years ago I had converted another ’66 to Freeze 12  It was a straight forward substitution that worked fine.  But I could not remember the charge conversion.  While searching to verify an earlier recommendation that mineral oil was the appropriate lubricant, I found several strong opinions that it must be mineral, must be ester or must be PAG oil……Guessing which is correct is not very effective. Thus my questions.

The charge appears to be 80-90% of R12. The datasheet states it is compatible with R12 lubricants, namely mineral oil.


I appreciate your time  in making your suggestions

Ralph

[Scot Minesinger]

Ralph,

I agree on the 1965-1970 Cadillacs r134 with std evap and cond just does not do the job of R12.  r134 seems to work for me much better on Cadillacs made 1971 and newer, likely due to larger condensers and air flows.

However, have worked on two Freeze 12 cars and both suffered very long histories of chronic failures by wealthy owners who both spent over 10k over a dozen years or so with never having enjoyed ac in their classic for an entire season.  I'm working on the one car now (converting to r134) as I write.  The other was finished about three years ago (1976 Eldorado w/r134 conversion) and the owner wrote to me just recently how wonderful his climate control was operating (and he moved to South FL). 

If I had a 1966 Cadillac closed car in a real warm climate would try to make some improvement so that r134 could work, such as larger condenser or alternate refrigerant like Greg used in his 1966 Cadillac.

Drove 200 miles today to a business meeting in my 1970 Convertible with top down - what a joy.  Since it was mostly highway at 70mph the 92'F was not unpleasant at all.  Got the deal and deposited my check at 4:50pm today.  I only use the r134 ac in this car when it rains (afternoon thunderstorms on the way home from car shows) and top is up, so it does the job no problem.

[mikanystrom]

I charged both my '68 Eldorado and '70 De Ville with "Envirosafe ES12a".  It's another propane/isobutane mixture.

From looking at the data sheets (they have vapor pressure data somewhere) this refrigerant, and many others like it, aren't really R12 replacements.  They are instead R134a replacements!  Who needs that, when you can get R134a in the store? 

Canadians, that's who...

In Canada, you need a license to buy even small cans of R134a, and you're supposed to track every ounce of the stuff.  So do-it-yourselfers are stuck with propane/isobutane north of the border.

What I wound up doing on both my cars is charge with 3 cans of ES12a (roughly equivalent to 4 lbs. R12) and then spiked it with about 100 grams of propane from Coleman/Sears.  That brings the temperatures down real low with the standard POA setting.  Good for So Cal but maybe too cold for Florida (risk of freezing up).

The only problem with propane/isobutane refrigerants is that their heat of vaporization isn't as great as R12 or even R134a (down by 20%? or so per unit volume of gas).  So you can get them real cold, but you will not have the cooling capacity you had before.  On the plus side your compressor doesn't work so hard.  If you live in a dry place, like I do, you can add more propane to get the temperature down way below freezing and recover most of the cooling.

The best part is this stuff is cheap, cheap, cheap... !

[Jeff Wilk]

Ok, this may be a silly question, but........if new replacement refrigerant comtains propane and/or butane isnt there a real BIG risk of explosion if a small A/C leak occurs???!

Jeff

[Scot Minesinger]

Jeff,

Yes if propane or other flammable gas contacts a heat source hot enough for ignition the gas will burn.  It may not explode (it could), but it will burn.  Might be like a Bunsen burner under hood.  However, the leak may not occur near a source of ignition.  Trans and ps steering fluid are both flammable, for that matter so is gasoline.

I read your point why risk it when r134 is available for not much money.  What is the upside gain ($30) vs downside risk (loss of entire car, death and etc.)?  I would use only r134 given the choice between it and a propane derivative. 

[mikanystrom]

This argument always comes up when "alternative refrigerants" are discussed.  If I were working on someone else's car as a business matter I would not put anything but R134a into it.  In my own car, it's different.

And it is definitely true that R12 was hailed as a miracle partly because it is noninflammable.  However it is likely that the bigger advance with R12 was that it is noncorrosive (as opposed to for example ammonia, another popular early refrigerant).

As you alluded to, the amount of refrigerant in the car is pretty small.  If you use propane in a "4-lb" system (4 lb of R12) it's about 1 1/2 pounds.

Propane (or call it R290 if you want to sound like a pro), as it turns out, doesn't like to burn under just any conditions.  It's relatively particular about the air/fuel ratio at which it will burn.  Unlike liquid hydrocarbons (such as gasoline) it also won't stick to your skin and burn you to the bone if you were to, God forbid, get into a fireball of the stuff.  It would probably be scary and you'd lose all your hair, but that's probably all that would happen.  And as far as I know it has never happened (not even in Canada).

There are a few reasons I'd consider using propane...

-- you can vent the stuff to the atmosphere with a relatively clear conscience (yeah it might be against the law, but it has no practical repercussions on the environment)

-- it's obviously cheap.  In California for example, with deposit laws and whatnot, a R134a charge can run you $50 just for the refrigerant.  $50 is not much, unless you have a lot of debugging to do, which might involve vacuuming your system several times.  With propane that's just no big deal.  Each full charge costs $3-$5 from Sears or $10 for a "professional" (non-scented, purified) refrigerant

-- propane is miscible with all the refrigerant oils (PAG, ester, and mineral)

-- you can tweak your propane/isobutane mixture to suit your system, which just isn't possible with R134a.  You can get closer to R12 vapor pressures as a function of temperature with propane/isobutane than you can ever do with R134a.  Or if you live in a dry climate, maybe you want colder than freezing?  Just put in more propane, less isobutane... your POA valve maintains 29 psig regardless of the refrigerant or temperature (ok there might be issues with superheat or something but at least you have another knob to tweak)

-- the fluorine-based refrigerants aren't without their own hazards.  Supposedly they CAN turn into HF (hydrofluoric acid) if they ignite.  That might be nastier than burning your eyebrows...

If you want something intermediate you can use "R152a" (air duster).  It's also relatively close in thermodynamic properties and less inflammable than propane/butane (more than R134a).  It's not that cheap though.  Half the price of R134a if you're not in California, a bit less if you are here.  I guess Californians (and people in places that restrict access to refrigerants) can recharge with "Freeze spray"....

http://www.qsource.com/p-1077-microcare-mcc-frza-anti-stat-micro-freeze-10-oz.aspx?utm_source=google&utm_medium=cpc&utm_campaign=Google%20Shopping&gclid=Cj0KEQjwo5--BRCS8ceLjv-XppUBEiQAGp15ELGB8v3boTxhxXiQXKr407mgXyMSEAErtV6UZhgsPtAaAn6L8P8HAQ


Propane (R290)

   H  H  H
    |  |  |
H-C-C-C-H
    |  |  |
   H  H  H

R12
     F
     |
Cl-C-Cl
     |
     F

R134a
    F  F
    |  |
F-C-C-H
    |  |
    F  H

R152a (air duster)
   
    F  H
    |  |
H-C-C-H
    |  |
    F  H

Basically, the F and Cl make the molecules noninflammable, but they are also bigger so they change the thermodynamic properties.  R12 is really cool because it has no H at all.  But chemically they are similar molecules.

And I wouldn't mix hydrocarbons and R134a.  That gives you some advantages thermodynamically but you now have a charge that is both inflammable AND potentially poisonous if it does burn.  That I see as the main downside with R152a... it's basically got a bit of both, so it won't burn on its own, but what if it burns as part of a bigger fire?  (Say a gasoline or PS fluid fire?)  Might not be so good.

[Dan LeBlanc]

That just made my head spin.

[mikanystrom]

Sorry...

[V63]

I have used 290 and am very pleased. Had one application reading 21 degrees at the vent, with little regard to ambient temperature. ! Very comfortable and I did not have an issue with icing with 2 years of daily use.

290 is much less likely to leak due to its molecule size. Lower pressures by 1/3. Less refrigerant volume by about a 1/3 too.

a source does advertise in hemmings.

290 is an ideal refrigerant EXCEPT for it is  flammable ...this was the motivation for DuPont to develop R12.

RALPH: the single best advancement in auto AC is in the modern CONDENSORS! Works With ANY refrigerant!  I highly recommend upgrading to this new technology! Just measure your old one and replace with similar size ($100?) I even adapted it into my old brackets. Replace ALL your hoses too with modern barrier hoses and green o rings. Flush evaporator. Disperse lubricant per shop manual. Further  I bypassed POA and went with modern cycling switch.  I just did all this on a stacked headlight model...it now blows at 35 degrees at 100f  Ambiant.

[V63]

Also: R290 is a laboratory grade NOT camp stove propane which is very dirty! Buy the laboratory grade, sold as a REFRIGERANT!