I decided to do a little research on this stuff so I gave Technical Chemical a phone call. Much to my surprise Freeze 12 is 80% 134a and to boot the oil charge is ester oil, which is what is used in 134a systems.

This stuff is really only good to top off (if that) because they recommend a full vac before using the stuff. If I'm gonna do a full vac then I'm going back with 134a to keep things simple. My compressor is noisy so it needs replacing anyway. Good thing I'm getting a take home patrol car this summer.

My point is... Well my opinion of this stuff is; it's not a good choice. It's not simple to put in due to the the tap on the can being a smaller thread, though a install kit is available, Freeze 12 isn't what I thought it really was, a true R-12 reworked formula.

FF

 

R-12 is simply not available.

The only serious options you have are to convert the AC to R134.

Unless you are into esoteric things like propane..

 

I wish propane weren't illegal or dangerous.

 

Propane is a lot less dangerous than its reputation.

I wonder what laws govern its use.

 

Are you saying it's not? If not let me know I'm wrong. I don't have a problem being told I'm wrong.

 

I dunno about the legality of using propane in an automotive a/c system. I will say that I have used es-12a which is a blend of propane and isobutane in a chevy van that I owned. The chevy's condenser is too small in my opinion for r134 so es-12a seemed like a cost effective way for me to charge a slowly (twice each season) leaking system in a van not worth fixing it correctly. It did a decent job. About the safety... Are you really concerned with a few ounces of propane when you are carrying 30+ gallons of gas?

I'd be happy to share my experience more in depth if anyone is interested.

Good luck,
Brian

 

Freeze 12 is a great product and have used it for about 10 years. I have it right now in 4 of my ex r12 trucks.
Cools better than R134a at a lower head pressure and it saves a lot of fuel with the AC on.
You also do not have to change hoses or condenser like you do when switching to R134a.
I am very happy with it, I am still running R134a in my 94 and 95 but thinking about switching them to Freeze 12 to get better fuel mileage and cooling.

 

Freeze12 is a very good product for what it was intended for. It's made to replace R12 without flushing the system and changing the oil. It can also be charged at the same amount, by weight, as R12.

R134a by itself will not carry the old R12 mineral based oil through the system, they don't mix. That's why Ester or PAG is speced for R134a.

FR12 is 80% R134a and 20% R142b. The R134a does the cooling and the R142b carries the mineral oil to lube the compressor.
I don't want to start an argument about whether FR12 works better than R134a, but if you look at the composition of both refrigerants you'll find the answer. R142b doesn't "cool" the pressures involved in an automotive system.

Freeze 12 still requires evacuating all of the R12 from the system, as mixing refrigerants changes the pressure/temperature properties of both refrigerants. (Mixing refrigerants is also illegal, per the EPA if you care). There are also issues with "topping off" blended refrigerants like FR12, but I won't go into that. Pulling the system into a hard vacuum before charging (from empty) is necessary regardless of the refrigerant used.

Back in 1993-1994 when R12 was phased out and many R12 systems were still fairly new, you could repair a leak, evacuate and recharge with Freeze 12.
Today, even the newest R12 systems are ~16 years old and usually need major service, instead of just a small leak repair. The seals are 16+ years old, as is the desiccant in the accumulator. Old desiccant bags can and often do rupture, especially if a system has been gown for some time. Repairs at this level require flushing the system and repalcing the oil.
You can add PAG or Ester oil and charge with R134a, or you could add Mineral Oil and charge with FR12. The end result would be the same. Johnsens now recommends Ester oil for use with FR12, pretty much negating it's biggest benefit.

Like I said, Freeze 12 is good for what it was intended for. However, it's not the be all end all that the manufacturer claimed back in the early days of system conversions.

Contrary to popular belief, R12 is still quite available and there is still a large supply. Due to lower demand, the price has also dropped considerably in the last few years. This, coupled with the recent price hike of R134a, R12 is again a viable choice for old systems. R12 can be found on Ebay for about $12-15/lb. The retail price is still very high because many places purchased their stock back when the price was in the stratosphere.
For $20, you can take an open book, online test to become "licensed" to purchase and use R12.

As far as propane and other Hydrocarbon refrigerants, that's a completely different can of worms.
Gases like Propane and Butane are excellent refrigerants and are used in many stationary systems in Europe. I'm not sure if they are used here in the US or not.
However, HCs are illegal to use in mobile AC systems in most states in the US.
This is due to the flammability of those gases and the litigious nature of our society. Unlike fuel, oil and other flammable liquids in a vehicle, the refrigerant in the AC system actually enters the passenger compartment. An evaporator leak could potentially cause a fire or explosion in the passenger compartment. Can you imagine the string of lawsuits that would occur if thus happened even once? It's considered much easier and safer to stick with standard refrigerants. (from a manufacturing and regulatory standpoint).
The Refrigerant Police won't come and haul you away for using an HC refrigerant in your own car, it's just not generally a good idea to use them when there are good, accepted refrigerants readily available.
In Canada, where R134a is highly regulated, HC refrigerants are quite legal to use and, I believe, are available over the counter.


For anyone not familiar with AC repair, I highly recommend: Automotive AC Information Forum - ACKITS.COM There's a ton of good info in the FAQ section and a lot of helpful folks on the forum.