Olds Dad

My '92 convertible is R-12 but needs service. I at one point had stockpiled a few cans and over the years have been able to give it a boost and have it work fine, but my supply has evaporated.

Now I'm considering a R-134A retrofit at an A/C service center that I trust.

Thoughts? Advice? Should do or shouldn't do's?

Thanks.

rcorrigan5

I don't know a whole lot about the mechanics of it, but when I had my compressor and dryer rebuilt for my '71 Corvette in 2003, I went with R-134. If there were any changes to parts, those two parts were the only things that were rebuilt. 11 years later, it still cools just fine and without any recharges.


Randy C.

Macadoo

There are several opinions on this subject. Some say the R12 condenser doesn't work as well with 134a, some say the POA valve (if you have one) needs to be re-calibrated. I got overwhelmed and just took it in for the conversion (after having my evap and condenser pressure tested) and it worked well. Very cold air....until my AC clutch seized a few hours later

jaunty75

R134a works fine. The system in my '73 Custom Cruiser runs with 134a, and it cools fine. The concerns about 134a have been greatly overblown over the years. Have the retrofit done, don't worry about it, and enjoy your air conditioning.

jag1886

Your same shop should be able to just fill it with R-12, most good shops stock it for older cars, it just costs a little more.
It costs a bunch to change over mainly because you have to put a new receiver drier in and get all the old oil out which is labor intensive, if your shop isn't recommending at least those 2 things then find a new shop.
I had my 65 converted back to R-12 because the air just didn't work right, it cost me almost $900 to convert back and there where no parts but new drier and freon, it was mostly labor getting the old oil out of everything. Now it works like a refrigerator.

edzolz

I converted a 78 to 134A and never had a bit of trouble. I never changed any hoses, connectors, valves, or anything but the oil. I flushed the system with acetone, evacuated it for about four hours and recharged it with 134A. the only difference I saw was if you want real cold air, run the fan on a slower speed. I don't think 134A exchanges heat as fast as R12.

Olds Dad

As I suspected...varying opinions.

I appreciate all the input - the "I did that and it works fine" success stories are encouraging.

I'll let you know what I do

Oldsmaniac

It did it on my 92 Custom Cruiser but swapped the compressor too as it was bad. 134A needs a different oil in the compressor than R12. So I had new oil and new compressor and 134A. My wagon has a large interior and it works good enough for me not to complain but slightly less cool than the r12. No regrets here.

Koda

To give a technical answer, R134a has different phase change properties than R12. As the liquid coolant flashes to gas in the evaporator, it absorbs thermal energy from the ambient air going by the evaporator. The compressor takes that gas, crams it into the condenser, where the heat loss and increased pressure jam it back down into liquid form. It then goes through some valving and back to the evaporator. Basic refrigerant cycle.

Begging pardon for the thermo lesson for those that know it already, but R12 requires less of a pressure change to phase change than R134A. Thus, your old R12 system is set to put R12 through its paces, not R134A, which is an inferior refrigerant. R134A works great in systems designed for it, and it works acceptably in systems designed for R12. The old compressor will not push the R134A as hard as it was designed to be pushed, so there will be less phase change energy transfer, ie, less cooling, than with the R12.

I have a car with R134A that was designed for R12. On a 100 degree day, it blew 66 degrees last time I had it charged from cooling outside air, one pass. It will freeze you out eventually. R134A will work acceptably for you; I'd say 80% of original cooling capability.

Olds Dad

The technical insight is appreciated (God I hated Thermodynamics)

Fortunately, I live in RI, not Arizona - so I'm thinking that even if I get the 80% you suggest, I'll probably be ok. If we see 100 degrees it's probably a nuclear attack

Macadoo

Yeah, I forgot about the dryer. I put in a new one and a new expansion valve. But that was just part of the AC rehab process for me. At the time I thought I was going with R12 but I couldn't find a shop that would do it. Even if I bought the gas on eBay. I also flushed the system with brake cleaner and blew it out with air.
Sorry about the brain fart. They seem to be getting more frequent.

Macadoo

I would agree. How's your average humidity though? In the midwest we can have 100 degrees with 100% humidity

oldsonharmont

Seems like those old GM axial compressors never died. I do live in Arizona, so it's R-12 for me.

MDchanic

Olds Dad is asking about a converting a 1992 vehicle.

I know absolutely nothing about 1990s Oldsmobiles, but it is not unlikely that that car already has a cross-flow condenser and a pressure-cycling valve, and it definitely has no POA valve.

I believe that you'd be in pretty good shape if you just changed your accumulator and your orifice tube, and possibly your low-side pressure switch.

- Eric

Olds Dad

The guy who runs the shop has more certifications and training in air conditioning than I could name - and is probably one of the smartest techs I've ever met (and also has been a close friend since we were fixing bicycles together instead of cars) - he is honest to a fault and will do the work correctly and in my best interest I have zero doubts -

I was looking for exactly what you guys gave me - some input and experiences regarding performance of the system with a proper 134a retrofit -

I'm leaving the car with him next week while I hide away in the smallest town I can find in upper coastal Maine.

I'll let you all know what happens when I get back

Fun71

I'm not sure I would come back...

Macadoo

Please do let us know.

71 OLDS

Upgraded my factory AC on the 70 supreme and will be doing the 71 442 the exact same way. Went with upgraded compressor (Pro6ten high performance 21 lbs lighter than stock (15lbs vs 36)), & parallel flow 6mm condenser w/6 rectangular tubes (like all new cars) with R134 conversion - blows ice cold at idle and/or low RPM.

For what it's worth the guy who did this for me said the reason people think the R12 is colder (usually at lower RPM and/or idle) is because they don't swap over to the "correct" condenser. The stock condensers are designed to work with R12 and all newer cars that have R134 have parallel flow 6mm condensers with 6 rectangular tubes. Not sure if this was BS or not but the new condenser I got from him was about the same price as buying a stock one and I'm extremely happy with the results. Ice cold air at all times plus I took off some weight with the lighter compressor. Here are some pics:

radiatorACfanshroud_zpsd2f6d2a0.jpg

motorleftside_zpsdd12304c.jpg

motortopview_zps6316de5d.jpg

Painted the compressor black so it looks stock. Going to put the red and silver sticker on there too so it will look even more original. Entire system cost about a $1,000 including the labor but everything is new. Compressor alone is $350 so it's not cheap to do this but again very happy with the results.

Olds Dad

I'm not back yet

Olds Dad

Looks nice!

Fun71

I think your AC guy is correct. A while back I was working in the garage in front of the cars and happened to notice the difference between the condenser on the Cutlass and the one one the new car. I grabbed my machinist's scale and measured the number of fins-per-inch on both: the Cutlass had 9 to 11 fins-per-inch vs. 18 or more on the new car. This means the new condenser is much more efficient at dissipating heat than the old one, which would translate to lower vent temperatures. At the time I thought about upgrading the condenser but didn't know where to get a modern one that would fit. Do you happen to have a part number for the one you have?

71 OLDS

Kenneth, I don't have it but I will get it and post here when I do. I need to have it for my 442 anyway when I get that done. I remember it was through one of the big ac companies like "Ice Cold Air" or something like that. I'll get all the details hopefully in the next week or so.

-Joe

MDchanic

This is true. While the A/C will still make the air colder than it was if you convert to R134 but keep the old condenser, it will not make the air as cold as it would with the right condenser.
R12 is a more efficient refrigerant, so in order to make R134 perform as well, other parts of the system have to be modified.

The importance of changing from a serpentine to a full-flow condenser has been discussed on numerous threads here, as well as in many other places.


... all other things being equal, which they are not, as R12 and R134 do not perform identically.

- Eric

lazy394

Like most people on here we all have tales to tell.
Mine is don't use Hydrocarbon based gases.
The sales pitch was the lower operation pressure, the down side is it burns. Well.
A recent engine fire was complicated by my inability to extinguish the burning gas being vented from the pressure relief valve on the back of my A6 compressor.
I now run R134 , with new hoses and thermal expansion valve, but the original steel condenser.
Its no where near as cold as the R12 or Hydrocarbon based gas, but it still beats no AC

Scott

illumined

I'd be really surprised if they could, R-12 has been banned and phased out for 20 years. It isn't produced any more and it isn't legal to buy it online.

MDchanic

It is perfectly legal to buy and install R12 if you are a licensed A/C tech.

True, it's illegal to make it in the US, but that's why the price is higher, and it's still legal to reclaim in the US, and to make in lots of third world countries, so there's plenty out there.

- Eric

Koda

Yeah, I got a 30lb tank a year ago, no issues.

Olds Dad

Got the car back with the 134A retrofit. No components changed - just evacuated the system, added the proper oil, and charged to (I believe) 80-85% of original R-12 capacity


Blows cold and works fine.


They did point out a small leak where the compressor is pressed together but he felt that it would last a while unless I wanted to replace the compressor and the accumulator. I chose the cheap "I'll let it ride" option.


So far, so good

jaunty75

Very interesting. This is what I've heard from several sources now over the years. That the original fear that conversion from R12 to R134a would require a major retrofit of the a/c system on the car in question has proved unfounded. For the most part, conversion from one refrigerant to the other has turned out to require nothing more than what you experienced. Drain the R12, put in R134a, and off you go. In your case, adding oil was required, too, but there was no changing out of any components. This was very much the experience I had with converting to 134a in my '73 Custom Cruiser.

71 OLDS

I've always heard that just flushing and adding 134 would work and there would be zero difference on a cooler day and/or when driving. The issue comes on the hottest days at idle or in traffic where the 134 just will not be cold enough (without the correct condenser). It will be similar to a newer car that is low on Freon. Works fine on a 75* day, and even on a 100* degree day as long as you are cruising. If it still blows ice cold on a 100* day in bumper to bumper traffic then maybe it really is an urban legend, like the headers on Supreme cars....

Macadoo

The would be the real test for sure.
Headers on a Supreme? What was that urban legend?

71 OLDS

Contact any big header company and tell them you want headers for a 70 or 71 or 72 Supreme and you will find out. Or try to order online. Most will say, sorry these headers will fit a Cutlass or a 442 but won't fit the Supreme body style. Not sure how or why this got started but it's just not true. Not saying you won't have issues installing headers but it will have nothing to do with it being a Supreme body style.....

joe_padavano

I did exactly this on both my B-body wagons, and the A/C cooled more than adequately the the 90 degree/90% conditions that they call summer here in DC. On the 86, I simply flushed and refilled. On the 84 the compressor leaked, so I changed the compressor, dryer, and orifice tube. My wife's 1985 D88 had the same thing done before we got it. All worked just fine.

johnnyjaws

what is the round thing in front of the rad is that the condenser ? car has ben sitting for ten plus years I have the grill out now so I guess it would be smart to replace ? right and were is the orfise tube also is it ok to put a trans oilcoller in front of the ac rad or is it called the. ? I don't know what its call .its in front of the rad

MDchanic

Hmmmm... Explain the entirety of automotive refrigeration and nomenclature... or offer a reference...


Have you ever heard of a thing called "Google"?

Do you have a Chassis Service Manual?

Go look up the principles of automotive air conditioning, and look up the names of the parts you have mentioned.

And your car does not have an orfise tube (or even an orifice tube). It has an expansion valve.

- Eric

nsnarsk65cutlass

The r134a is on it's way out ,the ones that are watching- EPA found out it causes more problems with the enviroment than the r12 did go figure.Nick