Smeddy2

I went to duracool's website and it looks like it is a great option to convert from R-12 as it has similar cooling properties without the hazard of affecting the ozone. I saw a couple people make mention of it here but no one has really said whether or not they have used it and what all was involved in the switch/how they like it. I think my compressor is bad so I plan on buying that and a new drier. Duracools website says that the EPA requires I change my system over to R-134a if I use Duracool. Does this mean I just need to get the R-134a fittings? Looking forward to hearing from you guys because its been a solid 95 here for the past couple weeks with almost 90% humidity....AKA my life is full of sweating.

girraffe

I just swapped my fittings after having to recharge. Haven't heard of duracool but after talking to my AC shop they said r134a is OK to use in a previous r12 section.

Smeddy2

Yeah I have read threads on switching to r134a. I like the ease of obtaining r134 and I already have the equipment to charge with r134 but it concerns me that it doesn't cool as well with a r12 system. That is why duracool sounds like a good alternative because it cools as well or better than r12 but has the ease of buying it like the r134. Maybe I'll just call them and see what all they say I'll need to make the switch. Where'd you get your fittings from? Are they just assorted or do they replace the r12 fittings all together?

Smeddy2

Sorry, I just fell victim to autocorrect because I'm on my phone. I meant to ask are they just adapters or do they replace the r12 fittings all together?

edeslaur

To convert to R134, it's a set of adapters you screw on, and o-rings to replace your existing ones. Cake.

I'm running R134 in mine. At idle, it's not as good, everywhere else it's been fine. This includes Houston in during a humid summer (used it as a toad with the motorhome)

cody o

I just did my fourth conversion to HC12a (same as Duracool) yesterday. I will post my write-up as soon as it's finished.

Smeddy2

Excellent! That would be great!

cody o

Write-up finished. Waiting for a mod to approve it for the Tech Write-Up Staging Area.

Smeddy2

Is it staged somewhere? I'd like to take a look if its already out there.

cody o

I think it has to be approved before it will appear in the staging area.

If I don't receive any objections, I can post it here as well.

Smeddy2

Ahh, I see. I will patiently await the knowledge before me.

cody o

Ah, what the heck.

Mods: If this violates any rules, please feel free to do whatever you need to.

Below is a copy of the thread I submitted for the Tech Write-Up section. By posting here maybe I can receive some feedback on my write-up.

cody o

I have been noticing many “how do I recharge my a/c” threads, so I would like to write an account of my experience in order to create a starting point for those wishing to perform their own a/c maintenance. I am by no means an expert, and I am not certified by anyone. This is not meant to be a reference or a substitute for your own research. It is meant to give the layman a starting point and a general idea of what to expect when recharging an air-conditioning system. Your actions are your own, so make sure you are confident in your understanding before you take action.

This is my fourth time performing this procedure. The vehicle is a 1994 Pickup DLX 22RE 4x4, which has an R134a system. The system needed recharging because I had to remove the evaporator in order to clean out a rat nest. This procedure was also performed previously on a ’91 Toyota 4Runner 3.0L, ’87 Toyota Van 4cyl, and an ’86 Toyota Cressida 6cyl, which all originally had R12 systems. (Can you tell I like ‘yotas?) Before you can start, you need the proper tools.



A set of manifold gauges is essential. I purchased this set off eBay for about $40, although I ended up receiving a full refund from the vendor due to a typo on their add. I intended to buy a set of R134a gauges, but ended up with R12 gauges instead. No matter, gauges are gauges, the only difference is the connectors. In the picture you can see three color-coded hoses. The blue is the “low side”, the red is the “high side”, and the yellow is the service hose. When the valves on the sides are opened or closed, their respective hose is connected or disconnected from the service hose.



I had to purchase an R12 to R134a conversion kit for my gauges since my truck has an R134a system. This kit cost about $30 on eBay and contains ‘quick connect” adapters for the high and low sides, as well as an adapter for the service hose.



This is a can-tapping valve, which cost $10 at Advance Auto Parts.



If you have an R12 system you are converting to R134a or hydrocarbon, you will need the retrofit adapters. This kit was $11 from Advance Auto Parts.



Since I already had an air compressor, I decided to go with a venturi-type vacuum pump. It requires a compressor that can deliver 4.2 CFM at 90 psi. This cost $15 from Harbor Freight. The alternative would be a standard vacuum pump for about $150-250.



Here’s the compressor I am working with.



I will be using hydrocarbon refrigerant in place of R134a. It cost $65 for twelve 6oz cans (equivalent to twelve 15oz cans of R134a). Even after the three previous vehicles, I still have six cans left; plenty for this project. The advantages of hydrocarbon refrigerant are many. It is an excellent alternative to both R12 and R134a. It is compatible with the oil used with both of those refrigerants, so draining the oil and replacing the drier are not necessary. It is more efficient than R12 and R134a, and also operates at lower pressures. It is not sensitive to moisture and will not form corrosive acids if water is present. There is much fear mongering on the internet regarding the use of hydrocarbon refrigerant. I have found none of it to have any base in reality, so I have no problem using it for myself and my family. You will have to decide for yourself if you choose to use it.



Here’s a close-up of the vacuum pump to illustrate the difference between R12 threads (vertical) and R134a threads (horizontal).



This is a Pressure versus Temperature graph for HC12a, R12, and R134a. (I added colored lines to the manufacturer’s graph.) To get a temperature of 38°F, I will charge to 40 psi. A pressure lower than this could result in a temperature below the freezing point of water, which would cause condensation to freeze to the evaporator coil.



It’s a beautiful balmy day in Georgia, my reason for undertaking this project.



Alright, now to get started! Now would be the time to install the retrofit adapters if this was an R12 system, but it’s not. In this picture, the high and low hoses are connected to their respective ports. The high and low “quick connect” connectors are different sizes for R134a, but for R12 the high and low threads are the same. This means if you are installing the retrofit adapters, care must be taken to put them on the correct port.



Here, the vacuum pump is connected to the service hose.



With the manifold valves closed, I connected the air compressor to the vacuum pump.



I found that the vacuum pump works great at 80psi. The compressor has no problem running it continuously. I opened both valves on the manifold to start evacuating the system. If you are using a standard vacuum pump, make sure to follow its directions to avoid damaging it.



A vacuum of 28inHg was achieved in about a minute. I let the vacuum pump continue to run for another ten minutes just to be sure. Then, I closed both manifold valves and turned off the vacuum pump (disconnected air supply). This step is important to make sure there are no leaks in the system. If the vacuum level drops, either there is still moisture in the system, or there is a leak. This system maintained 28inHg for over an hour, so I was satisfied there were no leaks.



Since system pressures fluctuate with engine RPM, it is important to hold a speed of 1200-1500rpm to achieve a proper charge. This truck doesn’t have a tachometer, so I connected this one to be sure I was holding the proper speed. It connects to the positive(+) battery terminal and the “IG-“ terminal next to the diagnostic port.



This refrigerant has the lubricant included in the can, so I didn’t have to add any extra. With the tapping-valve opened all the way, I screwed it onto a can of refrigerant. Then, I connected it to the service hose in place of the vacuum pump. Holding it upside-down (see arrows pointing up), I screwed the tapping valve all the way closed, and then all the way back open. This punctures the can and pressurizes the service hose. Slowly, I opened the low-side manifold valve to start pressurizing the system. Do not open the high-side valve! Once a charge has been achieved according to the chart, close the manifold valve.



Start the engine. Turn the air-conditioning on and set the fan to high. Open the windows to keep the cabin warm.



Holding 1500rpm with one hand on the throttle body, I continued to add refrigerant until the can was empty. Since I had not reached the proper charge, I had to change refrigerant cans. With the low-side manifold valve closed (remember, the high-side remains closed for the entire charging procedure), I replaced the empty can with a new one. I continued charging until the system maintained a steady 40psi on the low-side with the engine running at 1500rpm. This pressure will be lower if R12 or R134a are used (see chart). With the ambient temperature about 99°F, the low-side pressure is 40psi and the high-side is about 215psi.



I was curious what pressure the system would equalize to. It turned out to be 92psi in a hot engine compartment, on a hot day.



I added a label to indicate the system had been converted from R134a to HC12a. This is an important step. Anyone working on the system in the future will need to know what type of refrigerant it has.
It is my understanding that the EPA does not allow a system containing ozone-depleting refrigerant (R12) to be converted to hydrocarbon refrigerant. It does, however, allow a system containing ozone-depleting refrigerant (R12) to be converted to non-ozone depleting refrigerant (R134a), and non-ozone-depleting refrigerant (R134a) to be converted to hydrocarbon refrigerant. This is the reason why the R12 to R134a retrofit adapters should be installed when converting R12 to hydrocarbon. Basically, the system is being converted from an ozone-depleting refrigerant, to a non-ozone-depleting refrigerant, to a hydrocarbon refrigerant.

That’s it! A 15 mile test drive confirmed everything was working. This was my first time converting an R134a system to hydrocarbon. I have to say that I am very pleased with the results! Two of the three R12 systems I previously attempted were converted successfully to hydrocarbon. The two that were successful were converted from R12 straight to HC12a. The third was unsuccessful due to a badly damaged compressor. This vehicle had already been converted from R12 to R134a, and I suspect the damaged compressor was a result of an improper conversion. Converting R12 to hydrocarbon is much more forgiving than converting R12 to R134a. The vendor of the HC12a refrigerant I purchased even guarantees it will not damage your system!

I hope this gets you started down your path of research, good luck!

Smeddy2

I just have a couple clarifications/questions. When you evacuate the system with the vacuum pump, where does the old refrigerant go and what do you do with it? When you connect the first can of HC12, do you just allow the vacuum to pull it into the system and then after you have a partial charge, you start the truck and finish charging to the appropriate pressure for your temp? Finally, and I may be wrong about this, but I think I found something that says it's actually illegal to both use HC12a in an anything other than commercial refrigeration and it is also illegal to vent it. I'm kind of confused by the stuff listed in the link below because I have read elsewhere that it is okay to convert to HC12 (just like you mentioned above as long as you are going from R134a to HC12).

http://www.epa.gov/ozone/snap/refrigerants/hc-12a.html

cody o

Thanks for the reply!

The system had been properly cleared of R134a refrigerant about a year ago when I had to take the system apart. When I began this procedure, there was nothing but plain air in the system. Everything evacuated from the system using the vacuum pump I showed is vented to the atmosphere. The other three R12 systems I described had naturally leaked their refrigerant and were all empty when converted to R134a. Of course no R134a refrigerant was added as part of this conversion, so the systems were still empty when converted to hydrocarbon.

According to the page you provided, it is not legal to vent HC12a. I have changed my write-up accordingly. In reality though, there is no harm. It is non-toxic, non-ozone-depleting, and non-greenhouse. BBQ grills and butane lighters are vented to the atmosphere all the time without a problem, but once you call it a refrigerant, suddenly it's bad for the Earth.

When I connect the first can of refrigerant there is still a vacuum on the system. You might be able to make it out in the picture. With the first can, I filled the system from 28inHg to 40psi with the engine off. Then, I started the engine and continued charging while holding the RPM at 1500.

This appears to assert that DURACOOL 12a, OZ-12, and the old formulation of HC-12a, collectively referred to "Hydrocarbon Blend B", cannot be used in automobiles. Also, the new HC-12a cannot be used to replace any ozone-depleting refrigerant (R12). It doesn't appear to prohibit the use of HC-12a as a replacement for non-ozone-depleting refrigerants (R134a). Of course, I am not a lawyer, but I haven't seen anything that prohibit this.

Smeddy2

Haha I agree with you on the BBQ grill theory. Sometimes the EPA is just silly. I would have no moral qualms with releasing it into the atmosphere in regards to it actually "hurting the earth." I think you are probably right concerning your logic with the legality of HC12a. I will still call Duracool and see what they say about the illegal status the EPA has given them because they still market it as an automobile refrigerant. Where did you get your HC12a stuff....I don't remember reading about it in your write up?

Thanks for all of that, EXTREMELY helpful! I will probably take my truck to an AC shop and pay to get a check up to make sure it isn't leaking and to confirm my AC compressor needs replacing. I'll probably have them go ahead and evacuate the system if it still has anything in it.

cody o

I'm glad this helped!

Everything stated here is from my own research and experience, I have no formal training in this. It's not hard, but to the uninitiated it appears complicated. Hopefully this will help pierce the initial veil of confusion (and keep noobs from destroying their stuff ).

Yeah, if your system still has refrigerant in it you should probably have someone collect it for you. Or... drive to international waters and then vent it!


The refrigerant is produced by Northcutt, Inc.
http://www.hcrefrigerant.com

I purchased from OZ Technology, Inc.
http://oztechnologyinc.com

nomad26

Cody this is outstanding ! Thanks so much for sharing . I have 1989 truck and my air is working very cold and good at times and then other times it just dose not work at all hit and miss. Before I try your procedure I am wondering if someone has any ideas where I might try to trouble shoot this problem. I am hoping it might be a minor fix. This is my first time working with air conditioning systems.
Thanks

toyrunnerns

i read somewhere that you can not use hc 12a in any vehicle wether replacing r 12 or r 134a because it is flammable. it consist of propane and isobutane. it is illegal in the us to use. but there is only 2 to 3 pounds in the system and gas is just as flammable. maybe take that sticker off. good write up cody thats how i do it if i do not weigh it in, i am an ac/ref technician

cody o

The truck I showed in the write-up only took 7-8 ounces of refrigerant to reach proper charge. I know EPA legality is a grey area, but in all the research I've done I haven't seen any evidence that it's illegal to convert R134a to hydrocarbon.

Safety is addressed here:
https://www.yotatech.com/forums/f116...thread-237037/

Many millions of vehicles across the world have been using this stuff for a long time, just not in the US since Dupont had a refrigerant monopoly.