R-12 to R-134a Conversion on a Turbo Buick

[Roger]

To get optimum results, you'll also have to update the condenser & evaporator. 134 is not as efficient as R12 & runs at higher pressures.

Replace the rubber hoses in the lines which run to the compressor (I have seen them leak - not good when your working under the hood)

 

[aminga]

Doing this TODAY!!!! Ok, i bought the OEM style drier from the auto parts since they showed 2 part numbers. I bought the Ester oil with the UV dye in it just in case i have a leak. I bought a green r134a o ring kit and 4 cans of R134A. i rented a vacuum pump from Autozone for free ($99 deposit). I will flush the lines and evaporater core with Carb cleaner. I have a new conderser and compressor and I bought some r134a manifold gauges from harbor freight for $39 with (5 or 6 foot hoses). I bought the Red orifice tube P/N 38635 per Charlief1. Oh, i am also installing the Fbody radiator while i take out the condenser. Anyways, i hope this works like i want it to.

Here is a great write up from gnttype.org, pay special attention to all the steps especially the high pressure cut out switch.
CLICK HERE: AC 134a Retrofit

So this is just me but I'd use the A/C flush. It may be in the same stuff but the cost differential is nil

 

[aminga]

To get optimum results, you'll also have to update the condenser & evaporator. 134 is not as efficient as R12 & runs at higher pressures.

Replace the rubber hoses in the lines which run to the compressor (I have seen them leak - not good when your working under the hood)

Changing the condenser and evaporator adds a significant amount of cost for little benefit. If you get the pressures right it will cool. My system will get down to 45degrees at the discharge from the vents. The R-12 would go to mid to high 30's

Those of you with Original AC compressors the extra head pressure may kill it.

 

[charlief1]

Ok, at this point I'm going to do some corrections. The small line from the condensor to the AC unit is where the orifice tube is located. The fitting closest to the firewall is where it is. AZ part number is MT0093-1 for the red Ford tube. It's $1.99 so it's cheap. The accumulator needs to be replaced because it has dessicant in it and absorbs moisture in the system. Vacuum down the system which reduces contaminants like air in the system. Az has the suction pump in loan a tool so you don't have to buy one. You will need to buy a set of guages though. Harbor Freight has the best price on them and I've used several sets from them without any problems. You can get the flush in 1 quart containers or at AZ you can get a pressurized can with a line and nipple to blow out the condensor and lines. If you opt for the 1 quart then you pour it in and blow it out with compressed air. Remove the compressor if you're not replacing it and drain all the old oil out.

Pour the PAG 150 in the accumulator but make sure to lubricate all the O rings with a little before putting the fittings together. The accumulator is the very last thing that goes on because it has dessicant in it. Once you instal it imidiately start sucking it down and leave it on for at least an hour. If it doesn't hold vacuum then you have a leak and can check for one. If it holds vacuum then leave it on for another hour to make sure all moisture and air are aout of it. Then charge the system with the fan on high and im max cool position.

 

[HI85WH1]

Red Ford orifice tube?... I thought I used a blue one based on what I read here... you can seach for 134A conversion and one or more of those threads discusses the tubes.

 

[Red Regal T]

How do you do that? Is there a flush kit? Tryin' to learn here:smile:
Thanks in advance

Just go back to my original post or these guys will have you spending $500 to get your air working ..... unless you want to spend $500.. :tongue:

 

[Bruce Urie]

May I add....as one of the guys here said, replace all of your "o" rings on your air condition system and make sure you use the GREEN rings. They are compatable with the R134a. You can find them at Harbor Freight or AutoZone. Buy a complete set of rings so you'll have the right size there with you when you change the rings. Changing all of the rings in your system is not hard at all. Just make sure the system is discharged. And DO NOT leave any line, fitting, component open for more than 30 minutes, as the dryer will have to be replaced again if you do. You want the system closed as much as possible to keep the dryer from absorbing moisture. So, when you open a line, lube the ring with PAG OIL, put the ring on the fitting, then tighten it up. Then move to the next fitting. Use the green rings. Lube them at assembly. Let us know how you did.

You should have a vacuum on your a/c unit for 30 minutes before charging to evacuate your system of all air. Then charge it up. But, I'm sure others have done it differently and have had success.

Bruce '87 Grand National

 

[charlief1]

Red Ford orifice tube?... I thought I used a blue one based on what I read here... you can seach for 134A conversion and one or more of those threads discusses the tubes.

There is a GM blue that's used in late models. The color codes for Ford indicate the size of the orifices in the tube. The red has the largest at .0062 diameter per hole. The blue is at .0058, ect. The largest hole will cause the greatest change of state for the liquid to vapor tranformation and the greatest temp drop.

 

[Warp6]

May I add....as one of the guys here said, replace all of your "o" rings on your air condition system and make sure you use the GREEN rings.

Where are all the o-rings located. I've never had my system apart other than removing the compressor so, I know there are 2 o-rings there. I'm clueless about A/C systems so I really appreciate this post.

 

[norbs]

I have 134a in my car and I am removing it as it is totally junk. The problem is the compressor displacement volume is not enough for it to work efficiently. You a/c will work fine, but its a lot warmer than r12, i would use a replacement like freeze 12. I have changed the condensor to a highly efficient one and that helped 5 degrees across the board. The high head pressures will take out the compressor seal earlier also, as my new compressor is already leaking. The true way to test your a/c performance is in traffic, on a blistering hot day, sure while moving your will get 44 degree vent temps, but in traffic expect 55-58 degrees. Now i do have a huge front mount IC which is really not helping, but the biggest problem is the compressor can;t put out enough volume at low speeds in my opinion.

 

[Sal Lubrano]

GM White = .072 Stock (1 o-ring)
Ford Blue = .067 one step smaller (2 o-rings)
Ford Red = .062 Two steps smaller (2 o-rings)
GM Blue = .067 same as Ford Blue but 1 o-ring like the stock.

 

[Sal 87WE2]

Charlief1, 2 questions for you:

the low side retrofit valve has a valve core in it, do I keep or remove the valve core on the drier where it installs?

And, since you are in Texas what temps do you usually get at the vents?

 

[blackmonte]

I have 134a in my car and I am removing it as it is totally junk. The problem is the compressor displacement volume is not enough for it to work efficiently. You a/c will work fine, but its a lot warmer than r12, i would use a replacement like freeze 12. I have changed the condensor to a highly efficient one and that helped 5 degrees across the board. The high head pressures will take out the compressor seal earlier also, as my new compressor is already leaking. The true way to test your a/c performance is in traffic, on a blistering hot day, sure while moving your will get 44 degree vent temps, but in traffic expect 55-58 degrees. Now i do have a huge front mount IC which is really not helping, but the biggest problem is the compressor can;t put out enough volume at low speeds in my opinion.

Yep, thats why I run 409a in minehttp://www.arkema-inc.com/index.cfm?pag=36

 

[t-topflyer]

Thanks for all the great info so far.

I'll do a google search shortly to find out more, but for those who already know as it pertains to our cars, let me pick your brains..............

What is this freeze 12 stuff I keep seeing mentioned? I looked at autozone last night but didn't see anything on the shelf other than the 134 stuff. Maybe it's behind the counter

Can it be purchased without a special license and is it a direct replacement for the old R12 for our systems? And if it is, what's the catch?

 

[blackmonte]

No, Freeze 12 Freon Replacement: EPA Approved!

 

[shocker998md]

subscribed to this one.

ive heard good and bad things about freeze 12, i believe ive read where charlief1 talks about the bad.

ready for input about it.

 

[blackmonte]

Freeze 12 is a blended Refrigerant containing R134a and R142, an HCFC. The use of R142 allows it to be put into a mineral oil based system used for R12, which is why it makes a better conversion than straight R134 (which alone, requires the rather problematic PAG oil). Additionally, because it is blended, it has a better pressure/temperature characteristic than straight R134, and it does cool better. IMO The best use for Freeze 12 is to service or top off an existing R134 system. It will improve the performance of any R134 system. If your system is prone to leaks, I don't recommend this as the R134a component will find the leaks. Go directly to an HC, which doesn't tend to leak much.

 

[Sal Lubrano]

In addition to Blackmonte's post. R-142b (butane) which is carrying the mineral oil will leak out first since it is smaller than 134a. The system will continue to run but the gas will not be able to carry the oil to lubricate the compressor. If this happens the compressor will seize. Also, if you need to add more refrigerant to the system you have to completely evacuate then add a new charge. You can not "top off". Like I said before if you have a leak then you lost the 142b first so just by adding it will not be enough to lubricate the system. Another thing to remember our original driers were made for r-12 (xh-5). 134a will eat through the desiccant bad and destroy the system. Make sure you have the newer type (xh-7 or xh-9) drier before using that gas.

 

[charlief1]

GM White = .072 Stock (1 o-ring)
Ford Blue = .067 one step smaller (2 o-rings)
Ford Red = .062 Two steps smaller (2 o-rings)
GM Blue = .067 same as Ford Blue but 1 o-ring like the stock.

I had one zero to many but the biggest difference in the Ford versus the GM is that the Ford orifice tube uses two holes in it. This provides for a better change of stae in the refridgerent.

Charlief1, 2 questions for you:

the low side retrofit valve has a valve core in it, do I keep or remove the valve core on the drier where it installs?

And, since you are in Texas what temps do you usually get at the vents?

If everything is working right I can get 40 degrees out of my vents when it's 100 out. I keep thermometers in my outlets all the time so I can check performance. I have a compressor going out right now and need to do some changes to the systemto make it more effecent. With R-12 I've gotten temps in the mid 30's though. It really is more effecent.

Thanks for all the great info so far.

I'll do a google search shortly to find out more, but for those who already know as it pertains to our cars, let me pick your brains..............

What is this freeze 12 stuff I keep seeing mentioned? I looked at autozone last night but didn't see anything on the shelf other than the 134 stuff. Maybe it's behind the counter

Can it be purchased without a special license and is it a direct replacement for the old R12 for our systems? And if it is, what's the catch?

I tried Freeze 12 some time ago and it killed my compressor. I won't use it again because I've seen some issues with it not carrying the oil properly so the compressor isn't lubed right. It really is a hybred and the newer compressors need the right type of lube to work. R-12 really is the best one out there if you're willing to pay for it but I believe that the 409 is better than R-134. The reason we have R-134 is because Dupont researchers discovered that R-12 was harmful to the environment just as they finished the development of R-134 and the patent rights ran out for R-12. Figure that one out guys.

 

[charlief1]

In addition to Blackmonte's post. R-142b (butane) which is carrying the mineral oil will leak out first since it is smaller than 134a. The system will continue to run but the gas will not be able to carry the oil to lubricate the compressor. If this happens the compressor will seize. Also, if you need to add more refrigerant to the system you have to completely evacuate then add a new charge. You can not "top off". Like I said before if you have a leak then you lost the 142b first so just by adding it will not be enough to lubricate the system. Another thing to remember our original driers were made for r-12 (xh-5). 134a will eat through the desiccant bad and destroy the system. Make sure you have the newer type (xh-7 or xh-9) drier before using that gas.

Thanks Sal. I didn't think about the R-142b doing that. This explaines so much on how it killed my compressor.