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Old 05-26-10, 03:41 PM   #1
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Can I DIY R12 to R134 conversion? No R12 currently in the system...

I bought the car back in '99 and the AC has never worked. I figured out why several years ago when I changed the radiator. Because the receiver/dryer is in the way, you have to push it out of the way. When pushing the receiver/dryer back, the bolt head on one of the two bolts at the top of the unit popped off! There appeared to be glue (epoxy) residue underneath the bolt head. I'm guessing that someone overtightened the bolt at some point breaking off the head. They attempted to fix it with glue of all things, but all of the refrigerant probably vented into the atmosphere after the bolt head broke...

In any case, I extracted the broken bolt and replaced it with a new one and simply never used the AC (since at that time I was considering selling the car). I've decided to keep the car and I'm looking to get the AC working again. I'd like to convert it to R134A. Since there is no R12 in the system, can I simply buy one of the R134 conversion kits and do it myself? Should I get a new receiver/dryer? Are there special tools required to flush the mineral oil out of the system? I have no AC experience so any help would be greatly appreciated.

Thanks!
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Old 05-26-10, 04:09 PM   #2
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Here's the deal. http://www.freeze12.com/ is the easiest way to do it. It's a mix of stuff (including R-134) that can be used without changing anything over hardware wise. You can also do a "cheapo" R134 conversion pretty easily if you've got the kit. Neither solutions perform like OEM R134 systems.

I've done two cheapo R-134 conversions, and the problem is that when you really need it the A/C will never blow as cold as having real R12 in the system. What I mean by that is this:

do your quick R134 conversion. It's 70 degrees F outside and you put the A/C on. Blows ice cold and you're thinking "wow this works great." Well when it gets really hot outside (especially over 90 F) the A/C is just struggling, especially if you are sitting in traffic. It's barely cold and the car will not be comfortable inside except maybe when you are on the highway and have a lot of airflow over the condenser. The cheap R134 conversions are least efficient when you need them the most.

R12 is simply a better refrigerant. Cars with factory R134 have redesigned condensers for better heat exchange and other components that work better with R134. You may want to look into an aftermarket condenser and other components that might work better.
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Old 05-26-10, 04:27 PM   #3
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I use Envirosafe Industrial 12, it works much much better than r134
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Old 05-26-10, 04:28 PM   #4
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^ http://www.es-refrigerants.com/produ...14/default.asp
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Old 05-26-10, 05:14 PM   #5
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My car was converted from R12 to R-134 by a reputable shop. So far we've had triple digit temps here and the a/c still blows cold.
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Old 05-26-10, 06:14 PM   #6
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You will need a new drier.

You will also need to an AC vacuum pump to evacuate all the moisture out of the system after replacing the drier.

R12 is not as expensive as it is reputed to be. Just go to an AC shop and get them to vacuum and refill it for you. It should not cost more than about $150.
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Old 05-26-10, 11:37 PM   #7
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Quote:
Originally Posted by staticguitar313 View Post
My car was converted from R12 to R-134 by a reputable shop. So far we've had triple digit temps here and the a/c still blows cold.
Is there a list of parts that one would change when going from R12 to R-134? The previous owner mentioned changing it over however it does not work to this day and I would like to go back to R12 or the Freeze 12 product.
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Old 05-27-10, 12:35 AM   #8
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Last time I got my AC converted all it required the shop to do was to bleed out the system of the old gas and add an adaptor to accept the new R134. I was quite surprised on how simple the conversion was... It shouldn't take any shop more then 30 minutes to convert and refill.
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Old 05-27-10, 08:57 AM   #9
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Originally Posted by Brekyrself View Post
Is there a list of parts that one would change when going from R12 to R-134? The previous owner mentioned changing it over however it does not work to this day and I would like to go back to R12 or the Freeze 12 product.
Based on what I've read, I'm a little leery of all the R12 substitutes. Isn't Freeze 12 mainly R134 anyways, why not go the whole ten yards and convert it completely. The car is not my daily driver so I don't have to drive it when it's really hot, plus I don't have any AC right now so just about anything would be an improvement. I'd like to convert if at all possible, it'll make the system easier to maintain, better for the environment, and should increase resale value...

I've done a little research on the internet and this is what most sites recommend with an R12 to R134 conversion.

1. Reclaim/recover any R12 from the system (I can skip this step since mine doesn't have any refrigerant in the system).
2. Flush the system (minus the compressor) to remove mineral oil and contaminants (any good write-ups or how to specific for an FD available?)
3. Replace the o-rings with R134 compatible (green) ones (are there o-rings at every connection in the system? Can I skip this step?)
4. Replace the receiver/drier (ones made after 1995 should be OK)
5. Install R134 port fittings
6. Add R134 lubricant (where do I add it and how much?)
7. Evacuate the system (can I use this http://www.harborfreight.com/air-vac...ors-96677.html to simply pull vacuum?)
8. Charge the system with desired amount of R134

If anybody can answer the questions I included in the steps, it would be greatly appreciated.

Thanks!
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Old 05-27-10, 10:26 AM   #10
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if you dont have any 12 in the system right now then there is a reason. you have a leak in the system. in order to properly pull a vacuum on the system you have to locate that leak and fix it. anytime you open a refer system up you always replace the filter dryer.

1. there are many ways to find a leak but a little nitrogen, r12 (there will be a little in it due to the low pressure safety turning off the pump) , and a good leak detector will be the fastest and easiest.
2. once that leak is fixed no need to flush the oil just pull a vacuum on the system to 500 microns ( with a micron meter ) or 30" of vacuum for at least a half hour.
3. start the car and rev the motor to about 2000 rpm to simulate a driving condition and begin to charge. have a thermostat in the air vent and charge until 50 degree air comes out (this takes 2 people).
3. then you are done. If you have a friend or family member who is a hvac tech they can help tons. there is a lot of special equipment involved here to do this right. this is a very brief explanation of how to do it.
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Old 05-27-10, 01:00 PM   #11
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You are making this too complicated. I have written a couple of in depth threads on refrigerants that talk about the virtues of each, search on Freeze 12 and see if you can find them.

While it is true that R12 offers good performance, I personally wouldn't spend the money on it since you can get better performance from 2 cans of ES12a for about 1/10 the cost (the envirosafe product mentioned above). Not only will the AC cooling be as good, but it uses a lot less power to drive it and AC loading is hardly noticeable at all AND it's compatible with everything. If you are hell bent on using 134, then use Freeze 12 which contains some R152 iirc and is miscible with all oils.

Just be sure to vac out the system well with a professional (not harbor freight) vacuum pump for at least 30 mins and be sure it holds the vacuum before charging. Do you know what oil is in the system? IF not, use can add Ester oil if necessary to replace lost oil as it is compatible with mineral, PAG & PAO; the most common types.
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Old 05-27-10, 06:00 PM   #12
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it sounds complicated cause to do it right there are a series of steps you need to take or you will be doing it year after year. that gets annoying and costs a lot more in the long run
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Old 05-27-10, 06:13 PM   #13
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The most important thing is to pull a vacuum on the A/C system for at least 30 minutes, I'd probably do it for 45 minutes that way almost all of the moisture is allowed to escape. It's recommended to replace your drier and I think you should change to R-134a compatible gaskets and o-rings, but I've done these conversions without changing either and still had great success. Also you need adapter fittings to convert your lines from r12 to r134a, I usually go to NAPA and buy them individually. GL

Oh yea and don't forget to oil up the system and you might as well add a dye to the oil so you can search for leaks if you have any in the future.
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Old 05-27-10, 06:29 PM   #14
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Lol it's funny this thread came up about the vacuum pumps. I recently had an idea to use the engine's vacuum as the vacuum source. Think about it... you could modify the A/C fittings opposite end to pull vacuum from the brake booster line. This line gives you the largest vacuum source volume. You could also install a 1 way check valve and a vacuum gauge to check vacuum. At idle there obviously wouldn't be enough vacuum but you could rev the engine a few times to create maximum vacuum on the system when your almost done. I think it would work since the engine creates is highest vacuum during engine deceleration. Plus this is exactly what happens with the Fd's vacuum tank for the seq twin turbos. Now since were using the our own turbo engine, to avoid boost you would just simply rev to the higher rpm slowly then let it decel to pull higher vacuum. Anyhow, I think it could work without having to buy a pump.
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Old 05-27-10, 07:27 PM   #15
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i would not try that due to the fact that you are not only pulling moisture out of the system but small pockets of refrigerant that settle under the oil. as soon as a pressure difference is made in the lines the refrigerant will flash off and get removed by the pump. do you really want that going into the your engine? i dont. its a good theory though. also a good vacume pump pulls a lot more cfm then the engine does and electricity is a whole lot cheaper than fuel.
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Old 05-27-10, 08:01 PM   #16
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Quote:
Originally Posted by jectrx7 View Post
i would not try that due to the fact that you are not only pulling moisture out of the system but small pockets of refrigerant that settle under the oil. as soon as a pressure difference is made in the lines the refrigerant will flash off and get removed by the pump. do you really want that going into the your engine? i dont. its a good theory though. also a good vacume pump pulls a lot more cfm then the engine does and electricity is a whole lot cheaper than fuel.

Hmm that's nice to know about the flash off. How could there be a pressure difference if I'm using a check valve? I just hate spending money on a 1 time usage item. I still may try it (I just like experimenting a lot). My Fc has a reman A/C compressor that I put in 11 yrs ago. I recently recharged the system with freeze 12 and I didn't put a vacuum on it. That was 3yrs ago and my A/C is still working great. I've run water through my rotary's for years without any problems. I can't see some small refrigerant vapor doing much harm. Also gas is penny's if it only takes 10mins to put the required vacuum amount.
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Old 05-27-10, 10:47 PM   #17
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Originally Posted by neit_jnf View Post
I use Envirosafe Industrial 12, it works much much better than r134
+100

The ES Industrial 12 is SO MUCH BETTER here in the Florida humidity.

:-) neil
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Old 05-28-10, 09:10 AM   #18
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Quote:
Originally Posted by t-von View Post
Hmm that's nice to know about the flash off. How could there be a pressure difference if I'm using a check valve? I just hate spending money on a 1 time usage item. I still may try it (I just like experimenting a lot). My Fc has a reman A/C compressor that I put in 11 yrs ago. I recently recharged the system with freeze 12 and I didn't put a vacuum on it. That was 3yrs ago and my A/C is still working great. I've run water through my rotary's for years without any problems. I can't see some small refrigerant vapor doing much harm. Also gas is penny's if it only takes 10mins to put the required vacuum amount.
Aren't most refrigerants either butane or propane based? I don't think that you want that going through your engine.
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Old 05-28-10, 11:36 AM   #19
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Originally Posted by jectrx7 View Post
if you dont have any 12 in the system right now then there is a reason. you have a leak in the system. in order to properly pull a vacuum on the system you have to locate that leak and fix it. anytime you open a refer system up you always replace the filter dryer.

1. there are many ways to find a leak but a little nitrogen, r12 (there will be a little in it due to the low pressure safety turning off the pump) , and a good leak detector will be the fastest and easiest.
As I explained in my initial post, it appears that someone who had been previously working on the car must have broke a bolt on the receiver/drier. When I extracted the rest of the bolt and had the AC line open (on the high side?) nothing vented out of the system... Could there still be R12 in the low side that will need to be recovered? Keep in mind that I had the car for over 6 years before I figured out that the system had basically been open for at least that long. Is is safe to start taking things apart? I don't want the car to be responsible for damaging the ozone any more than it already has.

I absolutely intend to make sure that there is no leak by performing a vacuum test prior to charging the system. I actually want to flush the system to rid it of any oil and/or contaminants also before even performing the vacuum test.

Although I hear what everybody says in regards to the use of R12 substitutes (like Freeze 12 and ES12a), at this point I've decided to perform the conversion as a DIY project unless it becomes incredibly expensive or unfeasible, at which point I'll simply live without A/C like I have since I bought the car...

Thanks for all the help!
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Old 05-28-10, 12:02 PM   #20
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A lot of well-meaning but less than correct information in this thread.

Quote:
Originally Posted by jectrx7 View Post
it sounds complicated cause to do it right there are a series of steps you need to take or you will be doing it year after year. that gets annoying and costs a lot more in the long run
Yes, and it is complicated beyond the scope of this thread; however, not every step is relevant to automotive AC or is reasonably necessary. Don't fix things that aren't broke, open the system unnecessarily or do things arbitrarily.

Quote:
Originally Posted by therotaryrocket View Post
The most important thing is to pull a vacuum on the A/C system for at least 30 minutes, I'd probably do it for 45 minutes that way almost all of the moisture is allowed to escape. It's recommended to replace your drier and I think you should change to R-134a compatible gaskets and o-rings, but I've done these conversions without changing either and still had great success. Also you need adapter fittings to convert your lines from r12 to r134a, I usually go to NAPA and buy them individually. GL
+1 on the quick connect adaptors used for the 134 conversion. (You can use QC's with any refrigerant.) I just don't recommend a recharge with the usual r134a (for reasons cited elsewhere) as there are better alternatives. To properly install -134 you need compatible oil, materials and barrier hoses as well. R134 is a much smaller molecule than most of the other refrigerants and it will find leaks that you never had with R12. Beyond that, it gets further complicated and 134 performance will never be as good as R12 or the ES brand I-12a hydrocarbon substitute. Additionally, there is no need to replace the dryer unless the system has been open and wet.

Quote:
Oh yea and don't forget to oil up the system and you might as well add a dye to the oil so you can search for leaks if you have any in the future.
Don't overcharge the system with oil. Only replace oil that is lost, do not add extra and I wouldn't recommend adding dye at this point.

Quote:
Originally Posted by jectrx7 View Post
i would not try that due to the fact that you are not only pulling moisture out of the system but small pockets of refrigerant that settle under the oil. as soon as a pressure difference is made in the lines the refrigerant will flash off and get removed by the pump. do you really want that going into the your engine? i dont. its a good theory though. also a good vacume pump pulls a lot more cfm then the engine does and electricity is a whole lot cheaper than fuel.
Oil is miscible in refrigerant, thus oil will not trap refrigerant. The refrigerant will boil off as soon as you open the system to atmospheric pressure; it may be present in the system as a gas, but it isn't gonna be trapped by oil. Moreover, in order to get a reasonably "hard" vacuum, you need a real vacuum pump. An engine, modified compressor, cheap pump from harbor freight isn't gonna get you anywhere near the 500 micron range that you should see in a sealed & dry system. The compressor shaft seal is probably the most common point of leakage in an automotive system; fortunately the Denso unit used on the FD's has a better seal than most.

Once you've pulled a hard vac on the system for at least 30 minutes, close the valves & shut off the vac pump for 10-15 minutes and see if it holds. It will rise somewhat on a high-vacuum (micro) gauge, but you will not be able to see this on a standard compound charging gauge. From experience, if the needle on your compound gauge stays at about -30" and never rises, you're probably ok. I generally turn the pump back on and vac for a few more minutes. Gettting all of the air out of the system is important for good performance, otherwise the air will get trapped in the top of the condensor and reduce capacity and raise discharge pressures. Shut it off and charge in the first can of refrigerant with the vehicle off. From here it's gonna depend on the refrigerant you use as to how the rest is charged in.
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Old 05-28-10, 08:09 PM   #21
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Lol it's funny this thread came up about the vacuum pumps. I recently had an idea to use the engine's vacuum as the vacuum source. Think about it... you could modify the A/C fittings opposite end to pull vacuum from the brake booster line. This line gives you the largest vacuum source volume. You could also install a 1 way check valve and a vacuum gauge to check vacuum. At idle there obviously wouldn't be enough vacuum but you could rev the engine a few times to create maximum vacuum on the system when your almost done. I think it would work since the engine creates is highest vacuum during engine deceleration. Plus this is exactly what happens with the Fd's vacuum tank for the seq twin turbos. Now since were using the our own turbo engine, to avoid boost you would just simply rev to the higher rpm slowly then let it decel to pull higher vacuum. Anyhow, I think it could work without having to buy a pump.
You think wrong. The main purpose of pulling a vacuum on the system is to boil the moisture out...and the OP's system has PLENTY in it, since it has been open to the atmosphere for who knows how long. The engine will not generate a deep enough vacuum for a long enough period of time to boil the water off.

There's no reason to not use a proper vacuum pump, especially considering the cost of A/C system parts for these cars.
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Old 05-29-10, 01:40 AM   #22
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You think wrong. The main purpose of pulling a vacuum on the system is to boil the moisture out...and the OP's system has PLENTY in it, since it has been open to the atmosphere for who knows how long. The engine will not generate a deep enough vacuum for a long enough period of time to boil the water off.

There's no reason to not use a proper vacuum pump, especially considering the cost of A/C system parts for these cars.


I think wrong???? 1st off I never suggested to the OP that he try something like this did I? I was just curious to know if the engine vacuum thing was an option cause I never seen it done b4. Also in my other post I stated that I've run the freeze 12 in an un-vacuumed system and it still working perfectly fine 3yrs later. And this is on an cheap after market compressor I installed back in 1999. So I feel my little experiment may go just fine.
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Old 05-29-10, 01:40 AM
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