O.K. I have asked a couple of local parts guys, ASE techs and I am getting different answers. I want to change from R12 to R134a in my 88 GT. Some say all I have to do is change the fittings and put in different oil. Others say I need to change the compressor. Another says I need to change drier and orifice tube. Has anyone done one of these and got it right. I was told by one person that the dessicant in the drier is different for R12 than R134a and that the oil, PAG (spelling) oil will deteriorate the packet that the dessicant is in and cause dessicant to spread though the system. Can I get a straight answer and find out what is the minimum that is needed to change to R134a?
Thanks in advance.

There are many differing viewpoints

https://www.fiero.nl/forum/Forum2/HTML/109495.html

You can do it cheap and get 60-70% functionality or you can do it right and get 100%.

1. The cheap way is to buy one of those $20-30 conversion kits with the fittings, R134 and conversion oil.

2. The better way is to flush the system, change the orifice tube, change the drier, then vacuum the system, let it sit for 30 minutes, then fill with oil and R134. This should cost about $150-200 after buying all of the tools, parts and coolant.

3. The best way is to do the above only replace the compressor too. Add the cost of the compressor to #2.


You can probably do well with #2 unless your compressor is leaking. Then you need to replace the compressor anyway. Also, replace all o-rings on any fitting that you disconnect.

do you need the conversion kit if you change out the drier and orifice tube?

I agree with "Doug85GT".Acording to my Mechanic friend of mine.
Change the receiver drier and orifice tube.
You would most likley want to flush the system if there is any debrie,like metal in the filter (pardon my ignorance but I beleave thats the oriface tube).
New oil is R12 to 134a (Ester Oil),doesnt allways say on the front of the container so read the back too. (R12 to R134a).
A vacume pump to draw all the air out.
I beleave you will need new fittings (I dont know why).
I used to work for Sony and the dessicant,is a moisture obsorbeing packet to prevent rust,aluminimum doesnt rust so I would know why a dessicant pack would be inside the drier (we never placed a dessicant pack inside a product,we just droped it inside the box,then sealed the box)?Call an AC shop and find out,and Im sure they can easiley answer,any questions not covered.

[This message has been edited by James Bond 007 (edited 06-18-2010).]

quote Originally posted by wolfwolf: I want to change from R12 to R134a in my 88 GT ... what is the minimum that is needed to change to R134a?

See this thread. Also see this 2005 TSB from ACDelco.

You do not have to replace the compressor unless it's already broken or failing. Your information about the desiccant in the accumulator is essentially correct. The accumulator currently in the car may or may not already have the newer, R-134a-compatible desiccant in it, but there's no way to know for sure. Assuming that all other parts of the system are healthy, my "minimum list" includes the following:

- New accumulator
- New orifice tube
- New R-134a service port fittings
- New O-rings (only needed for connections opened up during conversion)
- PAG oil, 150 ISO viscosity (8 ounces)
- R-134a refrigerant (~34 ounces)
- EPA-required conversion label

While some may disagree, both GM and the EPA currently do not recommend flushing the system when converting to R-134a unless there is evidence of compressor failure (e.g. numerous metal flakes and/or a large amount of black "goo" or on the orifice tube filter screen). You do not need to replace the flexible hoses or any other O-rings unless they are already leaking; GM and the EPA agree that the mineral oil present in the system will have "sealed" them sufficiently for use with R-134a.

The total cost of everything listed above will be less than $100. Some may offer the opinion that you don't really need to replace the accumulator and orifice tube. My reply is, "Do it right or do it over."


Edit: Add recommended ISO viscosity for PAG lubricant.

[This message has been edited by Marvin McInnis (edited 06-18-2010).]

Unless you are an expert (I'm not) I've discovered that when it comes to a/c, the LESS you touch, the better!

The minimum you need to do is to replace the accumulator with a new one, the descants are different.
The new accum will probably have the correct 134 fitting on it.
You will need to add an adapter to the high side fitting. The adapter has a thread locker on it, once it's on it won't want to come off easily so make sure you've remopve the old valve (if you are going to do so) before installing the high side adapter.
Not sure if you need to remove the schraeder valve in the orig high side fitting before installing the adapter. If adapter has a valve in it then I think I would remove the old one otherwise you are relying on the new valve end pushing the old one down. If it doesn't, any gauge on the high side won't work! Not important unless you are using gauges, which you should but you can get by with guessing it (2 1/2 cans of 134 of so for a charge).
The different fittings are so that an a/c shop cannot connect up their r12 recovery equipment to your 134 filled system and contaminate their supply of recovered r12. They won't thank you if they contaminate their r12 because of incorrect fittings.

I wouldn't remove the orifice unless I had to or unless you suspect the compressor has grenaded and there's junk in the system in which case you are into some major flushing fun! The less you disturb on an a/c system the better.

It is my understanding that OE r12 systems had ester oil, OE 134 systems use PAG and retroft systems use POE (could have that the wrong way round, too lazy to check) but basically the oil you use for a retrofit system is compatible with the old r12 oil and the new descant in the accum so there is no need to flush/remove the old oil. In fact the old oil helps seal the old (r12) barrier hoses so for a retrofit, NOT flushing is actually better unless you are going to replace ALL the old rubber hoses with the newer r134 compatible hoses. This is because the molecule size of 134 is smaller than that of r12 so it will 'leak' through the old hose. The old oil has saturated into the old hoses and helps seal them.

You'll need a vacuum pump of some sort. I used one of those cheap compressor driven venturi pumps for a long time and wehile not 'great' it was reasonable. I picked up a 1.5 CFM pump recently from HF for around $90.

This information is worth what you paid for it, use with care!

Edit:
I defer to Marvin, he IS an expert!


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Dave

www.ltlfrari.com

[This message has been edited by ltlfrari (edited 06-18-2010).]

R-12 systems use mineral oil (not ester oil) as the compressor lubricant. R-134a requires either PAG oil or ester oil, but the ACDelco TSB states that ester oil is not approved for use in GM/Harrison/ACDelco compressors. Mineral oil is not compatible with R-134a, but both GM and the EPA agree that after conversion the residual mineral oil will just migrate harmlessly to the low points in the system and remain there.

Which viscosity of PAG to use is an excellent question, but I don't have a definitive answer. The ACDelco TSB specifies 150 ISO viscosity PAG oil for R4 and A6 compressors (not used in any Fiero) and 46 ISO viscosity PAG oil for "all other" GM/Harrison compressors. However, 4Seasons (probably the biggest aftermarket AC rebuilder/supplier in the U.S.) specifies 150 ISO viscosity for their rebuilt DA6/HR6 compressors and 46 ISO viscosity only for their new, proprietary equivalents. This document from 4Seasons specifies 125 ISO viscosity for V5 compressors and 150 ISO viscosity for DA6/HR6 compressors, and this document provides additional information. On the other hand, AC rebuilders Everco and Murray recommend 100 ISO viscosity ester oil for their rebuilt GM/Harrison compressors (all models). Most lubricant manufacturers and suppliers seem to specify 150 ISO PAG oil for use with DA6/HR6 compressors.

Bottom line ... It appears to me that 150 ISO viscosity PAG oil is probably the best lubricant choice for use with R-134a in the GM/Harrison HR6 compressors, while 125 ISO may be preferred for the V5 compressors. But my advice would be always to follow the compressor rebuilder's instructions, since they are the ones providing the warranty. If in doubt, ask.

[This message has been edited by Marvin McInnis (edited 06-18-2010).]

Indeed, you do not have to be a rocket scientist and get anal with details.... or you can. Your choice.
I've done it both ways with success.

Yes - you can get a retrofit kit and go to it... and it will work.
If your A/C system is working and just needs a recharge - this may be the way to go.
Yes - you can evacuate the system without flushing and just replace the refrigerant and it will work.

If you are in need of replacing parts, or your old A/C is barely making it... the go ahead and step up to the next level.
No doubt that replacing the compressor and accumulator and orifice tube and O-rings will give the desired results.

This has always been a sore subject with some folks.. and you can get scared to death by the details.
This is one of those issues that is like.... religion or politics. Some folks say that there is only one way and that is that.

Try it yourself, learn for yourself. You decide what works for you.
If your A/C is not working now... you have nothing to lose.

Great info Marvin!

Would like to add my 2 cents - 1st to emphasize - Replace the Accumulator and orifice tube! A partially plugged Orifice tube will not allow the system to work correctly no matter how many other parts you throw at it. A new accumulator with fresh - formulated desi is also important - moisture is the AC's biggest enemy and you can get one for like 20 bucks.

Regardless of which way you go, You really need to pull a vacuum on the system to get all the moisture out of the system and remove the air - this is even more important if you live in humid climate and if the system is opened to the atmosphere for any length of time. Pulling a vacuum on the system will also aid in determining if there is a leak in the system before you waste a can or 2 of refrigerant - if the system will not hold a vacuum, there is a leak somewhere (Pull a vacuum for about 30 minutes, close the valves and watch the gauge. Give it an hour while checking it perodically. If it drops, you have a leak somewhere - it could be in your gauge connections so double check them before you start looking elsewhere). I like to pull a vacuum for as long as I can - at least a couple hours and if you have time, let it sit over night - check to see if you lost vacuum overnight. If not, you are ready for charging. Another reason for pulling the vacuum is that it will aid in "pulling" the first can of refrigerent into the system. I like to get the first can in without the car running. If you pull a vacuum for long enough, the vacuum in the system and pressure in the can will nearly drain the can. Even if ths system holds a vacuum, does not mean that there is not a small leak somewhere. I always use the refrigerent with the dye in it for the first can. Once the 1st can is in the system, you can start the car with AC on Max. Get out your UV light and start looking at all the connections in the system, for leaks. If you find one, you are only out the 1st can.

If it's your first time, I would suggest that you pick up a "how to" DVD. Most parts stores have these for failry cheap - they go through step by step how to do it right the first time. Like Marvin says "do it right the first time or do it over". Good Luck!

Pat

quote Originally posted by Doug85GT: You can do it cheap and get 60-70% functionality or you can do it right and get 100%. 1. The cheap way is to buy one of those $20-30 conversion kits with the fittings, R134 and conversion oil. 2. The better way is to flush the system, change the orifice tube, change the drier, then vacuum the system, let it sit for 30 minutes, then fill with oil and R134. This should cost about $150-200 after buying all of the tools, parts and coolant. 3. The best way is to do the above only replace the compressor too. Add the cost of the compressor to #2. You can probably do well with #2 unless your compressor is leaking. Then you need to replace the compressor anyway. Also, replace all o-rings on any fitting that you disconnect.

I agree with Doug that doing it the right way will produce great results with R-134A. You can get it so cold that you'll freeze your balls off.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

This source specified 135 for PAG oil, and 100 for Ester oil, for GM compressors. I have seen other sources that say 150 for PAG. In any case, I have PAG 150 in my 88 duke (with V5 compressor), and it works just fine.
I have never seen PAG 135 in stores, and I figure 150 is close enough.

quote Originally posted by TopNotch: I have never seen PAG 135 in stores, and I figure 150 is close enough.

That's why I didn't even mention it. 46, 100, and 150 are the PAG viscositites commonly available. I've seen 125 available on-line, but never in a store.

[This message has been edited by Marvin McInnis (edited 06-18-2010).]

It comes down to the law of diminishing returns. The trouble to vacuum out the system and replace the drier, in my opinion, does not give the benefit necessary to justify the trouble or expense. I have done the el-cheapo job about a dozen times. If we were talking about a larger car I could see the rationale but the Fiero will get very comfortable very fast with the straight oil swap.

I did 3 vehicles over the years, an 87 Caddy and 2 Chevy conversion vans. We did the bare minimum, fittings and fill with the proper lube. All three went to their graves with good working air. I would not spend one dime more based on my experience.

JMO, but if system is usuable, try to stick with the R12. All of the newer cars Ive had with 134 didnt cool nearly as well. The only real times I use AC is when a girl is riding and dont want her hair to blow. Opening the windows is almost as efficient as 134. Its been mid 80s here for weeks and the few times Ive had it on in the sebring and it seems to me it dont make 5* in temp difference. Same with my Magnum (nothing is wrong with either). The R12 in my Fieros and Corvettes kept soft drinks cold for hours just placed in front of the vents. Ive never tried any of the aftermarket substitues so cant say anything about them.

I replaced some easy to reach O-Rings, the Receiver/Dryer, the compressor (ALWAYS get an HR6 and not a DA6 for a 6cyl car!). I can walk out to my car when it's hot enough inside to fry eggs, start it with the AC on max, and return 3 or 4 minutes later to shiver when I step into the car. My advice is to just do it right the first time. Those charges/recharges every time you screw up and have to replace another part add up fast.

------------------
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Thanks for all the info. One question. How do I know what oil to use to be compatable with the reciever/dryer and the dessicant bag. If I order a Fiero reciever/dryer I am going to get one that used r-12 type dessicant? Right? How do I know that I have the reciever/dryer that is compatable with the r-134a and the associated dessicant. I understand that if I use PAG oil I cannot use the r-12 type reciver/dryer as the oil will deteriate the dessicant and then it screwing up the compressor etc. Do I use the ester oil to be sure that it is compatable with the r-134 and the available reciever/dryer? or do all the reciever/dryers now come with r-134 and PAG oil compatability? I want to do it right and have no problems. I would rather research the issue and do it right once. Thanks.

The desiccant in any new accumulator you buy today will be compatible with R-134a, PAG oil, and ester oil ... as well as backward compatible with R-12 and mineral oil, too. Concerning the choice of lubricant for use with R-134a, see my previous posts in this thread.

[This message has been edited by Marvin McInnis (edited 06-19-2010).]

quote Originally posted by Toddster: It comes down to the law of diminishing returns. The trouble to vacuum out the system and replace the drier, in my opinion, does not give the benefit necessary to justify the trouble or expense. I have done the el-cheapo job about a dozen times. If we were talking about a larger car I could see the rationale but the Fiero will get very comfortable very fast with the straight oil swap.

The problem with not replacing the accumulator (and desiccant) is that moisture in the system mixes with the refrigerant oil and forms acids - obviously not good for the other parts of the system. It's not just about cooling performance. In addition, replacement of the accumulator and orifice tube is both easy and cheap. It makes no sense to risk destroying the compressor by not replacing a $3 part and spending 30 minutes to do so.

A caveat is that, if this is a V6 car, the factory DA6 compressor probably will not survive long with R-134a, even if its currently working. It was not designed to withstand the additional head pressure of R-134a. It may be worth replacing your DA6 (if you have one) with a HR6 before you waste money on refrigerant. I got a USA-rebuilt Factory Aire HR6 for $140 at Advance Auto - they run specials on their website all the time.

Marvin's post noting the different oil types is interesting as I did not know Ester was not an approved lubricant. (I've always used Ester for conversions) but its also worth noting that my Fiero has tremendous cooling performance with R-134a.

[This message has been edited by masospaghetti (edited 06-20-2010).]

quote Originally posted by masospaghetti: ... I did not know Ester was not an approved lubricant.

I agree with you. Replacing the accumulator and orifice tube is cost effective and just makes good sense. The DA6 compressor was marginal even with R-12; wear of the aluminum cylinder bores was a chronic problem, and the less efficient lubrication inherent in R-134a systems makes things even worse.

I didn't know of the GM oil recommendation either, until I came across that ACDelco TSB. I suspect that the disapproval of ester oil may only apply to some compressors used by GM, but right now what's stated in the TSB is all I know.

[This message has been edited by Marvin McInnis (edited 07-01-2010).]

quote Originally posted by rogergarrison: JMO, but if system is usuable, try to stick with the R12. All of the newer cars Ive had with 134 didnt cool nearly as well. The only real times I use AC is when a girl is riding and dont want her hair to blow. Opening the windows is almost as efficient as 134. Its been mid 80s here for weeks and the few times Ive had it on in the sebring and it seems to me it dont make 5* in temp difference. Same with my Magnum (nothing is wrong with either). The R12 in my Fieros and Corvettes kept soft drinks cold for hours just placed in front of the vents. Ive never tried any of the aftermarket substitues so cant say anything about them.

Your AC problems are a lot deeper than 134a.