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R-12 to R-134A

chevyCowboy

chevyCowboy

I might be crazy but i ain't dumb
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back before i blew up my motor i hit a deer and it took out my ac condesor so i need to get a new one of those. and sice i have the every thing takein apart right now i was wondering if there are any other components to the ac system that need to be changed to make it compatible with an r-134a system.

will the compressor i have work? i dont even know if it is in good working condition though beacouse the ac has never worked since i bought the truck.

i know very little about ac systems so im hopeing somebody can learn me a thing or two
 
I'd still talk to a shop first.

You may be able to swap over to r134a easily.

Not every system requires replacement of the receiver dryer. Swapping of oils and whatnot usually takes place when evacuating and recharging the system.

IMO, it's worth swapping to 134 as r12 is expensive, hard to find, and soon no longer to be.....
 
Nah your system is already purged, they sell kits $40 ish when I converted my 90, from 12 to 134, new dryer, orifice tube, you'll have a new condenser, if your compressor is ok you can drain the oil from old one and refill with oil compatible with 134, or if getting new compressor add in 134 friendly oil, PAG IIRC is the name, new fittings for charging system thread over the old ones.

Pretty simple conversion actually.

This assumes you have access to a vac pump, 134 gauges, and can pull a vac on system
 
A better choice would be Envirosafe. You only need to evacuate the system after the repairs and then charge with the envirosafe.

This product is colder then 134 and fully compatible with the system and the oils used.

You can buy it online and the only changes are that you need to install the 134 charging ports (adapters available at the parts store)

134A is not really all that great in the R12 system due to the size of the condenser and evaporator.


Missy
 
so all that needs to be done is change out the fittings, then apply x amount of vacume to the system for x amount of time. and then refill with this envirosafe (or 134A)

do you know what it is that makes it work better than the 134a in theses older systems?
 
Not that this is the correct way of doing it, just sharing my experience. 1990 Buick the local shop wanted $300 to convert it to 134. I was considering having them do it when I stumbled onto a $40 kit at Kmart to do a 134 conversion. I depressurized the remainder of the R12 installed the new fitting charged the system & viola worked like a charm.

Prolly not the way one should do it, but worked for me...
 
SfcJones said:
I forget the name of the replacement for R12 but it requires no mods....
Click to expand...

I'm guessing your talking about Freeze 12?

I'm going with R12 in my blazer, but that's only because I have some here already. If I didn't have it, it would be set up for 134A once I replace/reinstall the entire system.

There are many places that still have it buried somewhere's in the store, probably forgotten. It's very pricey and you need a license to purchase it. My job has some buried under the counters and it's $35 per 12 oz can.
 
Last edited:
Turbine Doc said:
PAG IIRC is the name, new fittings for charging system thread over the old ones.

Pretty simple conversion actually.

This assumes you have access to a vac pump, 134 gauges, and can pull a vac on system
Click to expand...


Never use PAG Oil in an R134a Conversion. PAG oil is ONLY to be used in FACTORTY Equipped R134a Vehichles. Use Esther Oil. Is can mix with any residue from the mineral oil(R12) and won't hurt the older hoses and seals. PAG Oil will eat the crap out of an R12 system. I don't use it at all even in the 134a systems just because I stock more Esther Oil for conversions.
 
MGW has had good luck with subsititutes but I personally have not. I did a few jobs years ago with Hot Shot and some other stuff I don't even remember the name of and they all came back next season with blow compressors. Maybe the stuff has gotten better since then. After that exerience I have never used it again. I will not work on an R12 system unless it is in for conversion. Like Dave said, way too expensive. I have the license to buy it(it's a joke anyway) and I don't use it.
 
From experiences that others have shared with me... 134a is a whole different animal if you are comparing to an R12 "experience." R12 would run a colder air temp out of the vents. R134a has more ability to move heat (more efficient)... so it needs a bigger condenser like Missy said. It will get cold, but may not be what you are used to with the original R12 in it.

Also, do a little bit of reading on POE (ester oil). It is a very good system detergent. It will clean out any debris on the inside. I don't think that it was as highly rated as PAG was. Been a while, but check up on "black death."

Edumacation now is priceless later.
 
As mentioned above dont use PAG in that system, unless you replace the accumulator and compressor, take every fitting apart and flush the lines/evaporator/condenser real well, then its still a gamble.

On R12 to R134a conversions that ended up with PAG that I do, usually had Ester oil with a new accumulator or drier and compressor with complete flush previously.

PAG oil does seem to lubricate alot better than ester though, just risky to use in conversions.

If it was my truck, I'd charge with Freeze-12 and leave the system stock. Or change the orfice tube, change the fittings, dump some Ester in it, charge with 134a and get the rest of the life out of your old compressor. I'd replace the accumulator if the system has been left open and flush it if you find alot of trash in the orfice tube. Then when/if the compressor takes a dump, replace compressor/accumulator/orfice tube/o-rings, flush the lines/evaporator/condenser, drop in some ester and 134a.
 
Crankme69 said:
Not that this is the correct way of doing it, just sharing my experience. 1990 Buick the local shop wanted $300 to convert it to 134. I was considering having them do it when I stumbled onto a $40 kit at Kmart to do a 134 conversion. I depressurized the remainder of the R12 installed the new fitting charged the system & viola worked like a charm.

Prolly not the way one should do it, but worked for me...
Click to expand...

Almost exactly the same experience converting the '86 burb to R134, $45 conversion kit from local auto parts chain (R&S Strauss). I dunno what happened to the R12 but "the system was already depressurized" which is how I came about to converting it because no can buy R12 anymore. (You all know they "finally" figured out that freon "free radicals" do not deplete the ozone layer as they originally claimed 40 years ago forcing conversions & retrofits at billions of dollars to be paid by, who else, us? Same group of scamentists who claim that CO2 causes green house effect, which was, BTW, also proven to be another falsehood, but billions will be spent again by us... But I digress...) The R134 worked "okay" but nowhere near "COLD" as the R12 that was in there before. Even with our '06 Avalanche, the air coming out of the vents is "really good" but not freezing as the good old days...
 
The R12 substitutes such as freeze 12 and a few others are mixtures of a few different materials.

The envirosafe is not any of these.

ES can be used in a 134 system as well and is completely compatible with any of the oils and the components.

It takes about only 1/3 the amount of ES to do the job too. The stuff smells like pine sol so you can tell right off iof you have a leak in the evaporator core (heater/ac box)

Look the stuff up online.

You just need to be sure the system is sound, pull a vacuum of 29" hg for 30 minutes to extract any old materials and moisture. Install the prescribed amount of ES through the low side port and your set.

There is nothing secret or fancy about ES, its a hydrocarbon based refrigerant and has a coefficient of heat that is even better than R12.

The stuff has a flash point of 1300F if in the right concentrations. This material is far better than 134 simply because it is far less toxic.

It still has the cold/freeze hazards of any refrigerant and displaces oxygen in confined spaces. (reason for the added odor agent)

All common precautions need to be observed when handling this or any refrigerant product.

Comes in the small 1 pound cans or a 30 pound pail.

The other stuff like Freeze 12, Hot shot and a host of other R12 replacements are just not worth the time and missery IMHO.

134A in an R12 system is trouble no matter what you do, unless you completely clean, flush and update the system to a full fledged 134A system.

With the ES product, its a simple, repair any damage, evacuate, recharge. Get cool.


Missy
 
Just a side note.

134A when used in a system that is designed for it, will cool very well.

The issue is the size of the condenser and its ability to reject heat and the size of the evaporator.

The compressor is about the same other than the materials use in the seals.

A good 134A system in a GM pickup should produce air at the vent outlets in the 42F range on an 85F day.

The issue of course is keeping the surface of the avaporator above 32F Air temps in the vent outlets much below about 40F will see evaporator surface temps near the freezing point. This condition will see the condensate freeze to the core and the system will ice up and stop working.

The main difference between the 134 and the 12 systems is the way the evaporator and condenser cores are made inside. The rows of tubes (how many) and the construction of the interior of the tubes.

134 does not have the ability to move as much heat from point A to point B for any given amount of refrigerant flow.

To make it all real simple, this is why the conversions dont work as well even when done by the instructions in the KITS.

They will keep the car COOL but not as well in really hot weather.

THE ES product is actually colder and will work just as good as R12
In some systems you need to install an adjustable low side switch to keep the core from freezing up.

AC is a simple change in state of a heat absorbing medium (refrigerant) High pressure liquid, flashes to a low pressure gas as it passes through a small orifice. Low pressure gas is compressed to a high pressure gas, passed through the condenser and becomes a High pressure liquid again and then back through the orifice and on it goes.


Missy
 
Missy Good Wench said:
There is nothing secret or fancy about ES, its a hydrocarbon based refrigerant and has a coefficient of heat that is even better than R12.
Click to expand...

Duracool is another name.

Sadly it is not legal to use it in AZ. :mad2:
 
I don't know where all this R134a doesn't work as good stuff comes from. The only thing I have ever noticed is systems with smaller CFM compressors(Mostly Macks and Pete's with those junk Sanden 6cfm) take a little longer to get cold intially but once your rolling it works just as good. I have converted many many many Macks, Peterbilts and Cat HE with no issues or complaints. My 90 Burb is running R134a and it works fine. I've never really measured but by eye the Condensor in my r12 Burb and the condensor in my R134a Dually look pretty close to me. PAg oil also eats the crap out of the hoses and Orings on an R12 system. Not recommended. Esther oil works fine. Years ago on R12 we used Baby Oil.
 
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