R12 or R34A

gr8scott · January 25, 2013

For the second time in two months, my AC is losing its charge. Since I'm not a DIY car guy I have to have someone add it, and shops charge $70 a pound plus labor. Since I may need to have the system completely drained to replace some seals or valves, what with the price difference in refrigerants I wonder if this wouldn't be the time to switch to the newer freon. Is there anything else involved beside changing the valve fittings?

D-a-n-i-e-l · January 25, 2013

It is a simple process. The R134a is much cheaper and readily available. If you have brought it in for AC service it is very likely they already did it. It will save you money in the long run to switch. the down side is that system is designed for R12 and runns more effeciantly with it. this means that your AC will never be quite as cool with R134a, but most do not notice the change as it is minute especially in our cars that use the same AC system as the much larger GM cars.

PONTIAC1953 · January 25, 2013

r134a will leak out quicker than r12, you need to have your leak located and repaired before spending more money on refills. charles coker, 1953 pontiac tech advisor.

padgett · January 25, 2013

Any car need maintenance, old cars need more. A complete retrofit would include all new seals and new manifold hoses but few go this far, with new oill many do not even bother to flush.

A/C work is expensive but necessary in this part of the world. That said 134A does find more ways to leak than 12 but have gone whole years without having to add any. Of course a good R-12 system can go for decades.

handmedownreatta · January 25, 2013

mine was converted to 134 by the dealer.i have to recharge it several times a year.my camaro is still r12.it needs one can a year.

January 25, 2013

Generally, the time to consider the switch to 134a is when compressor needs replacement and the system needs to be flushed anyway. If sticking with R12 precludes the need for a flush, then the savings from not flushing can offset the added cost. If flushing is warranted anyway, then switching to 134a will probably be the less expensive way to go.

If system doesn't need to be opened to fix the leak, then it probably makes sense to stay with R12.

ol' yeller · January 25, 2013

To add to Padgett's list, the dessicant is over 20 years old so the drier should be replaced. When changing to R134A the orafice tube should also be replaced. Both can be had inexpensively on Ronnie's site.

Machiner 55 · January 26, 2013

The photo below shows all of the components of an AC system removed from a 1989 Buick Reatta. The Evaporator is the only item not readily removed from the car. (the one shown came from my '88) It can, and should, be flushed while still in the vehicle. The Liquid Line and the Suction Line can be removed from the car but it’s not necessary to remove them to flush them. The components that are either not flushable or recommended to be replaced are the:

1.) Compressor.

2.) Accumulator.

3.) Refrigerant Lines w/ Muffler.

4.) Condenser.

5.) Orifice Tube.

The Reatta Store has all this stuff.

Leaks can develop anywhere in the system. Likely locations are:

1.) At the joints where the lines connect the various components. All of these connections have “O” rings inserted to seal the joint. If joint is broken, rings must be replaced.

2.) The Compressor body. If leaking, replace it.

3.) The Condenser. If leaking, replace it. Due to it's construction, it it said that it's not possible to completely flush out contaminants. So, replace it.

4.) The Valve Bodies where gauge connections are made and refrigerant introduced. The valves are similar to the valve stem valves on your tires. The valve assembly unscrews itself then leaks.

5.) The points where the various Temperature and Pressure Sensors connect to the lines. The sensors are threaded to the lines. These also can come loose and leak. There are "O"-rings located here also.

6.) If you find out that the Evaporator is leaking… sell the car.

The best way to check for leaks is to introduce a refrigerant die into the system. Run the system then, in a darkened garage, go over every square inch of the system starting with the aforementioned locations with a UV light. To fix the leak, the system must be evacuated.

There are many opinions as to what to do when converting from R-12 to R134a. Here’s mine. Take the car to a service center to have the system evacuated. Flush the Evaporator and the two lines going to and from. Replace all five of the items listed above. This includes the “O”-rings at all connections including the sensors. Use PAG oil compatible rings. They are typically light green in color. Now you have two more choices.

1.) Take the car back to the service center for the recharge or …

2.) Before charging, you'll need to evacuate the system with a vacuum pump. This is done for two reasons. A.) To remove moisture from the system and B.) to check for leaks before adding refrigerant. You won't know where the leak is at this point but you will know that the system won't hold pressure if it won't hold a vacuum.

3.) Charge the system with a Manifold Gauge set according to the instructions that came with the set and in the FSM, yourself. You’ll have to get a can of refrigerant that contains the dye or buy a small bottle of dye and mix the recommended amount in with the oil.

4.) After the charge, check for leaks with a UV light kit. No leaks? Then you’re done.

It was mentioned that you’re not much of a do it yourself'er. Well… when you go to the service center for the system evacuation, tell them you want a R-134a conversion. Give them your credit card and be done with it. Should only set you back $1000.

Please see my addendum to this post below in post #13. Thanks.

Edited January 26, 2013 by Machiner 55
Change in Charging instructins. See addendum. (see edit history)

KDirk · January 26, 2013

I'd just chime in here that if doing major repairs (i.e. compressor or dryer) then I'd change to 134A. 12 is coming down in price now, as there are many fewer systems that need it due to the number of retrofits and outright replacements; thus the price per pound has peaked. So, you might find a "deal" on a quantity of 12, but it is a dead end anyway as there has been no new manufacture for quite a few years now. Some stockpiles here and there from companies/people who had foresight to buy a bunch before the ban hit, but these have been dwindling for a long time now. I have one 30lb pig left I have been holding in reserve, but once the 91 is converted to 134a this spring, I may well sell it as I will have nothing left that needs it.

If you are willing to spend the time (or money for a shop to the work) for a complete tear down and rebuild of the system w/flush, no reason I can see to go back to 12. Yes, it gets a bit cooler in practice than 134A, but unless you are in a locale with terribly inhospitable summer weather (ala Death Valley CA) 134A can usually do the job, even if it takes a bit longer to hit target temperature in the cabin. Of course, window tint helps the cause and I highly recommend it provided you don't run afoul of the local authorities by doing so, I went max legal tint (for Missouri) on mine and have never been hassled over it once.

KDirk

Doug Harness · January 26, 2013

Our ’91 was converted to R134A in 2010 when the compressor went out. The bill including the compressor was $674.39. It has made it through 2 summers and has not required any additional coolant.

Our ’89 was converted to R134A in 2004. The bill for the conversion was $183.96. It has made it through 9 summers and has not required any additional coolant.

I really can’t tell any difference in cooling. We have hot summers, but we don’t have the high humidity of the southeast.

Edited January 26, 2013 by Doug Harness (see edit history)

SeanR · January 26, 2013

Sorry but I disagree that R134 is not as cold and that it will leak faster than R12. Any prior system that had R12 and that has an HR6 compressor (Reatta has HR6), even to GM official standard's, is an excellent conversion candidate so as long as the compressor isn't headed for impending failure. My Fiero has R134 and it's ice cold.

Mineral oils from past R12 charge block R134 molecules from leaking through the hoses, unless it's a physical hose/O-ring/compressor seal failure then no matter what type it's going to leak out (which is the whole point of why we are discussing this in the first place - R12 leakage, so you can't fault R134 if it also leaks). However, if the system is discharged, it would be a prime opportunity to refill it with dye and find out specifically where it's leaking.

It's most likely leaking at one of the points mentioned above and you would want to officially convert all the oring points to green orings, replace the accumulator, orifice, and potentially condenser (most likely no, since compressor hasn't had an internal failure). Looking at the orifice filter tube for metal shavings and tar like blockage would determine the condensers fate. The only way to inspect the orifice is to open a completely discharged system, and if it's already at that point, might as well replace the o-rings, etc. If you don't change out the accumulator, the old silicate won't catch moisture effectively, and the orifice will ice over and cause a pressure kaboom at the weak spots.

If you are going to open the system up for repair, might as well take your rubber hose off and a local hose shop will recrimp them with Goodyear hoses anywhere from $50-100.

You also have to charge PAG46 oil and add R134 up to 85% of R12 weight on the underhood sticker in order to work properly. Less freon required compared to R12. Not as well known fact, so some folks try to add equal parts R134 as R12 and that affects R134 efficiency. GM does not recommend flushing the condensor because the flush is hard to remove and will weaken the new R134/PAG oil charge. You might be able to leave the condenser as-is, as long as the orifice filter is clean.

To DIY, would have to buy set of manifold gauges and vacuum pump from Harbor Freight.

Source: http://forums.aaca.org/f116/c-compressor-do-i-need-hr6-165655.html

Youtube has several DIY series R&R videos. DiscountACParts.com - YouTube

Fiero.nl technical section also has excellent conversion articles covering the various compressor models ultimately over to HR6/R134.

Wish that I could attach word docs here, but the forum doesnt seem to allow .doc items.

Edited January 26, 2013 by SeanR
text (see edit history)

January 26, 2013

i don't recommend anyone do any of this on their own....there is some high pressure on one end, and how many people have a vacuum pump?

134 is harder on your system because of the higher psi it runs at, about 20 psi more, which means it will leak out faster..

always stick with r12....if you can.

Machiner 55 · January 26, 2013

Addendum to post #8.

As always, the post by Sean is well written, well thought out and technically correct. I will amend my post to include the statement that to get the proper charge in the system one should, in addition to pulling a vacuum, use a manifold gauge set and know how to operate them. If not properly used, one can destroy a perfectly good compressor. How, you may ask? If the high side pressure is allowed to mix with the suction side thru the manifold then, the comp. is toast. Don’t ask me how I know.

Anyway…

I am also going to amend my post to eliminate the statement about getting an R-134a recharge kit or retrofit kit. If one has gone through the trouble of replacing items one thru five, then the only sensible course of action is to refill the system as it was meant to be done. This requires that the proper amount of oil be introduce into the system. When performing the system flush, what is being done in addition to removing contaminants is that you’re removing all of the oil from the system as well. Recharging the system reintroduces two components, the oil and the refrigerant. The Kits have oil mixed in with the refrigerant but, if you haven’t flushed the system and or replaced the compressor, then you don’t know how much oil is remaining. You don’t want to overfill the system with the oil. You’ve got to know how much is in the system to be able to add the required amount. This is why I recommend replacing the five parts and flushing the rest. You are then left with a system with zero oil. The HR-6 compressor system in a 1989 Reatta has a recommended oil capacity of 8.0 fl. Oz. When refilling a totally evacuated and flushed system, half of that amount (4 oz.) goes into the compressor and the other half (4 oz.) goes into the accumulator. Now, some compressors come with the oil already added. These compressors should have a tag or some other documentation stating whether or not they have oil in them and what the quantity of that oil is. It may say that there is two ounces of oil already in the compressor. If that is so, then you’ll only have to add an additional 6 fl. oz. to the system to bring it to a total of 8 fl. Oz.

The dye can be mixed with the oil prior to adding it to the system. I would add the dye to the portion of oil that you are going to put into the accumulator. Reason being, that when adding the oil to the compressor through the suction side, you are to turn the compressor to cycle the oil through the internals. (You are to turn the compressor not just the clutch assembly) This act can be messy with the oil bubbling out of the holes. If there is dye in the oil, then it’ll get on the outside of the compressor and later, when you are looking for leaks you’ll think you’ve got a bad comp. out of the box. The accumulator, on the other hand, is easily cleaned of the oil/dye mixture prior to installation.

Once the oil/dye has been added, the components are then installed. The compressor is turned over by hand once again to make sure it spins without locking up. (You are to turn the compressor not just the clutch assembly) Then, the system is connected to a vacuum source and brought to -29 to - 30 in. hg. This removes water vapor and atmosphere from the system. (Water vapor left in will freeze over the orifice tube and damage the system) After a period of time, if the system is found to hold a vacuum, indicating no leaks, then the introduction of refrigerant can begin.

Instructions on how to charge the system are found in the FSM as well as the oil and refrigerant capacities. Instructions as to how to operate and interpret manifold gauge pressure readings come with the gauge sets. Additional instructions and information can be found on the Internet and YouTube for them as well as how-to’s on vacuum pump operation.

The above is not meant to be an all inclusive step by step instruction on how to recharge an AC system. It’s just to give one an idea of what’s involved. It can be done by any reasonably mechanically inclined individual with access to commonly available tools. I am living proof of that, being a product of a Polish and Ukrainian union, educated in the United State Public Educational system. The only thing I can’t figure out is, which half left the high-side pressure valve open on the manifold.

One more thing…

If you are going to open the system up for repair, might as well take your rubber hose off and a local hose shop will recrimp them with Goodyear hoses anywhere from $50-100.

If I’m not mistaken, the hoses being referred to here are the ones that include the muffler and are bolted to the compressor. If that is true, then a new set of these can be purchased for about $95.00. I’ve been told that because if the integral muffle, that these can’t be flushed. Rather than pay for new rubber, just get a whole new assembly.

I just ran across a factoid in the FSM regarding the Muffler. It says that there are filter screens inside the Muffler to prevent debris from contaminating the refrigerant system in the event of a compressor failure and that “The flushing procedure previously used is not necessary on vehicles equipped with the Muffler Assembly. Since we’re going to R-134a and the hoses are two decades old, just change them.

John F.

PS.

I’ve included a photo of the Manifold Gauge set that I use as well as the Vacuum Pump. Yes, they were acquired at H.F. (Almost ashamed to say) This Vac. Pump, although cheap, does do the job as well as the motorized pumps do. But… you must have a very capable air compressor to run this type of pump to achieve the required vacuum. (Which I do) Besides already having the required air compressor, I couldn’t see paying about $150.00 for the motorized one when the cheapie, on sale, cost about 8 bux. On the other hand, it’s a lot cheaper to run the little motorized units than it is to run Big Bertha here but you gotta go with what you got. Another thing about the little guy. There’s nothing inside the plastic case except a venturi block and a couple pieces of pipe. I modified mine a bit by adding the pressure gauge and an inline water separator because I thought it was a good idea. To the inside, I unscrewed the pipes from the block and applied pipe compound to the threads. Then I wadded up some fiberglass insulation to dampen the noise of the air rushing out of the venturi block. It helped quite a bit.

Edited January 26, 2013 by Machiner 55
Add text and photos. (see edit history)

January 26, 2013

anyone here familiar with this new refrigerant? HFO-1234yf: EPA approves new air conditioning refrigerant | The Car Tech blog - CNET Reviews

Machiner 55 · January 26, 2013

Is there anything else involved beside changing the valve fittings?

To answer Scott's original question here, in a word... yes.

John F.

January 27, 2013

About three or four years ago my original compressor began to have a slow leak. I found a company that sold me a new (not rebuilt) compressor,accumulator, and orfice tube. Total bill was $166.00 including shipping. I also bought a can of ester oil which is ok with R-12 or 134a. On craigslist I found six cans of NOS DuPont R-12 for $80.00. My mechanic replaced all the old items and flushed out what he could. Tightened all the fittings and evacuated it then let it sit overnight. In the morning there was no leakage so he sucked in 4 ounces (i think) of ester oil then charged it with three cans of R-12. Labor to R&R the o-tube, compressor and acumulator with evacuation was $160.00 System has been working well with no problems. I still have 3 cans of R-12 for a back up but since I used ester oil swapping to 134a would be easy. I would change the orfice tube and evacuate it and charge it with the proper amount of 134a. The company that sold me the hard parts is listed in the resources section.

Edited January 27, 2013 by Richard D (see edit history)

gr8scott · February 5, 2013

I took it to the shop, where they located a purported leak at the compressor.

Here's the estimate for the repair:

Remove and replace AC Compresor, receiver dryer and orifice tube

Upgrade system to 134A Freon.................................................. $340

Flush system of all debris from failed compressor and old R12 residue. $85

AC Service ............................................................................ $40

Parts:

AC Compressor 313

Receiver dryer 80

Orifice tube 9

Flush kit 50

Retrofit Kit 48

2.5 lb R134A 87

Total: about $1050 plus tax

Depending on regional variations, is that about right?

Bushwack · February 5, 2013

I took it to the shop, where they located a purported leak at the compressor.
Here's the estimate for the repair:
Remove and replace AC Compresor, receiver dryer and orifice tube
Upgrade system to 134A Freon.................................................. $340
Flush system of all debris from failed compressor and old R12 residue. $85
AC Service ............................................................................ $40
Parts:
AC Compressor 313
Receiver dryer 80
Orifice tube 9
Flush kit 50
Retrofit Kit 48
2.5 lb R134A 87
Total: about $1050 plus tax
Depending on regional variations, is that about right?

Right on the money (pardon the pun). That's about my average cost for replacing 3 compressors the past few years. For this job, cost for parts and labor is about a 50/50 split. You can supply a new compressor for $75 less but if there's a problem with it, guess who will have to pay up for additional labor?

February 5, 2013

agree with Ervin - price sounds about right - especially being in so-cal. i doubt i'd get a much better deal here in NC.

if you know this shop, and trust they will stand behind their work, etc. go for it!

if not, it wouldn't hurt to get a "second opinion" estimate...

Machiner 55 · February 6, 2013

A week ago, in a rather long winded and detailed post, I said this,

It was mentioned that you’re not much of a do it yourself'er. Well… when you go to the service center for the system evacuation, tell them you want a R-134a conversion. Give them your credit card and be done with it. Should only set you back $1000.

What more do you want?

John F.

Edited February 6, 2013 by Machiner 55 (see edit history)

February 6, 2013

John, for the "record" i thought you were right also. sorry i forgot about your post. i really thought the price would be inflated more given it's so-cal, (lived there for 26 years when i was a "mere yout")...

February 6, 2013

Just reminds me why I do my own work.

Will there be tax on top of this too?

Bushwack · February 6, 2013

Just reminds me why I do my own work.
Will there be tax on top of this too?

But of course! California loves, loves, loves to tax the consumer. I think L.A. was just bumped to 9% (not sure about Carlsbad - probably 8%).

Ronnie · February 6, 2013

But of course! California loves, loves, loves to tax the consumer. I think L.A. was just bumped to 9% (not sure about Carlsbad - probably 8%).

Not as bad as I would have thought. Tenn. is 9.75% but we don't have income or personal property tax like some states. Some states give a sales tax break on food but not Tenn.

March 4, 2013

nothing works as good as r-12..i use it all my old cars/trucks.

R12 or R34A

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