auto a/c r12 to r134a conversion

[Nandy]

For the short version just skip to the questions.

Long story...
I had 3 vehicles with ac problems so when I went to harbor freights and found a 2.5 cfm vacuum and the automotive a/c manifold for $40 dollars less than regular price I knew I had to have it. Here a simply vacuum and oil fill cost $160.00. I had 2 cars that need that and one that I had no idea what was the problem. Today I set up to tackle one car, maybe 2.

The altima ac was not working at all. When I went to work in it today I decided to find the clutch power input so I could hot wire it if I need to. I wanted to do this with a cool vehicle. To my surprise, I saw that the compressor did not have a belt. Easy fix... Got the belt at the local autoparts and fire it up. The cars started to make a bad bearing sound. I fire the ac at full blast check the manifold and added 2 cans of gas and it worked. I looked for the bearing sound and found it to be the bearing for the idler pulley. $50.00 new... no way, went to the local junk yard and after inspecting 2 vehicles I picked the pulley that felt smoot and no shaking. Vehicle one fixed...

The camry is an 89 vehcile with the r12 gas in it. It would cool a bit in the night and nothing during the day. I decided to do the retrofit. I read much about it and there are so many different takes in it that there is no way to figure what is what you have to do. So I decided to follow a website instructions. Not being able to find (I had already checked) a shop that will take the r12 for free I reluctantly let it evacuate in the atmosphere. After all, that is what it happens when you have a leak. I vacuum the system for 30 min and stopped for 10 min to make sure the gauges will not move to indicate a leak. All looking fine I did the last 10 min of recommended vacuum. Turn the car and ac for 3 min. and started to load the freon. It did not take long and the ac was cooling fine. 36 oz after I was done. I found that the gauge does not measure accurate and I guess I have a faulty gauge but I will ask for just in case...

Questions:
Manifold: http://www.harborfreight.com/a-c-manifold-gauge-set-92649.html
Vacuum: http://www.harborfreight.com/25-cfm-vacuum-pump-98076.html

The manifold has multiple scales in both gauges. The most outer scales is the 134a scale. When I place my gauge in the sytems the measurements are around the 10 psi and when I use the gauge that comes with the kit it shows over 25 psi. Am I reading it wrong? Having an electronic background I am used to read needle meter with multiple scales so I think Im reading it right, but maybe someone out there knows something I dont.

When I had the vacuum connected to the manifold the oil in it went from clear to a milk chocolate like color. Is that normal?

On the camry the valve was still leaking once I took the hose off. Both the original r12 valve and the r134a valve. I put the cap as it has an o ring and I am hoping it holds. If the regular cap dont work, what are my options?

Any information and help from those that has done this work will be welcome.

 

[dolluper]

Re: auto a/c r12 to r134a conversion

You may have overfilled....r12 ..17oz equals 15oz of 134....36 onces sounds like to much
Kit guage???? ...this brings a question the kit was r134 or hydocarbon kit...{duracool}
low side 28-45 reading >>> high side 5-10% r12 less.....20-30% less r134

 

[Nandy]

Re: auto a/c r12 to r134a conversion

I remember reading much that it will be unlikely to use all 3 bottles but the kit does have a gauge much like the ones sold in Walmart that comes with the bottle attached. You can use the gauge without the bottle to just check the amount of gas. Both vehicles showed in the green zone which is the 25 to 45 psi so I dont think it is overcharged. However the new harbor freight manifold differed much. Actually, by the reading on the manifold these ac should not be working as the pressure was really low (about 10 psi).
Here is the kit:
http://www.idqusa.com/proddetail.php?prod=RKR-8

Im positive it is 134a. I remember that I should use 80 percent less 134a than r12 but there are no labels anywhere in this car to tell me what was used.

I need to return this gauge and get the high side reading and compare... Another thing I noticed is that the low side gauge reach to like 38 psi... Is that normal?

 

[SS MAYFLOAT]

Re: auto a/c r12 to r134a conversion

One of the things that most of these kits lacks in telling you is that the oils from 12 and 134 are not compatable. Could be why your oil has changed to a brown color. I prefer using R414b in R12 systems as it is compatable. However, you need to be a certified tech to obtain it.

 

[Nandy]

Re: auto a/c r12 to r134a conversion

I remember reading that too. But it was more like the mineral oil from the r12 system will not be compatible with the new oil (they recommended to use ester oil and not pag). However, you are right, the kit dont tell you anything about it.
As far as the oil that change color. It was the oil in the vacuum pump. This pump has a glass port with an index line in the frame so you can see your oil level. I applied the pump before adding anything so I doubt it has anything to do with the oil in the kit.
I was surprised to see how many other gases are out there for this application. But since only 134a is available to the non-licensed individual I did not look much into them.

As far as the schrader valve leaking, what can I do with it? just hope the cap will keep the gas in? I hate to have to loose all the refrigerant I used here but is it possible to replace just the valve. is it the same size as the tires ones? I doubt it... Right now it has the new valve screwed in but I would have no problem taking that one out if it needed and will save the new valve for any future work.

One more thing, if I have to open up the system for fix this leak in the schrader valve is there any way for me to recover that r134a that is not going to cost $1500? The cheapest freon recovering machine I have seen is 800 which is not an option. I might work in the a/c once a year top. I got the vacuum pump as an option to also use it for fiberglass and the manifold was just silly not to buy. If not I can pay the $30 some dollars in gas.
Thanks!!!

 

[DECK SWABBER 58]

Re: auto a/c r12 to r134a conversion

low side 28-45 reading >>> high side 5-10% r12 less.....20-30% less r134

Don't you mean higher? Low side: 28-45 is good, High side is going to be 150 to 250 (or higher) depending on outside temp.

A simple rule of thumb for refrig. level that will give you a general idea.
With system off both guages will just about match ambient temp if system is
fully charged. IE: If 80 deg., 80 lbs. pressure.

Confused on the schaeder valve issue. R-12 valve cores look exactly like tire
valve cores but are different. R-134A valves are totally different. To charge
with 134A you did change the fittings right? The cap will not seal it you need
to change it, it's defective. First try opening it with a pocket screwdriver letting
some freon out, sometimes a little piece of dirt gets stuck in there.

Your vacumn pump oil should not look cloudy, it's getting contaminated somehow. The system was totally discharged before evacuating wasn't it ?

 

[Nandy]

Re: auto a/c r12 to r134a conversion

Ok, gauge are right. Operator error. I was reading the outside scale that is labeled r134a. I should have been reading the psi scale which is the most inside scale. Now they read right. Both of them are over low 30psi-high 150psi. Still low for 80 deg but it is working.

I did change the r12 valves but all you have to do is unscrew the new valves (r134a) if I need to. I did unscrew the new valve and it was leaking. The new valve is pretty much a pass trhu valve that so if the original valve (r12) leaks this one will leak too. When I rechecked the pressures today they were just like yesterday but I could tell the high pressure valve is also leaking. What I am looking for is a good cap to keep them from leaking. Im not sure they are leaking now but those are plastic caps and im not sure the durability.

In simpler words. If you had an r12 or r134a system leaking thru the valves, how can you fix it or is there are caps for this purpose. I rather have both answers because I am not taking those valves out right now as the system is working fine. BUT if I have to take the system apart in the future I want to know if there anything that can be done like replacing the needles that goes inside of the valve.

thanks!

 

[Nandy]

Re: auto a/c r12 to r134a conversion

Yes, the system was evacuated using the old system... Looking at the oil now it really dont look that dark. It is transparent milky. Must have been when I looked at it in the dark that it looked darker...

 

[dolluper]

Re: auto a/c r12 to r134a conversion

yep your going to have to replace the rubber hemisphere seals on both the high and low side,lose all your charge...that's where most systems lose their charge from...If I were you I would look at using a hydrocarbon kit instead like duracool or redtex? 2cans would fill your system the molucles are larger and they also sells a system drier in a can plus a system sealer in a can....cost you about 50-70 bones

 

[j_martin]

Re: auto a/c r12 to r134a conversion

yep your going to have to replace the rubber hemisphere seals on both the high and low side,lose all your charge...that's where most systems lose their charge from...If I were you I would look at using a hydrocarbon kit instead like duracool or redtex? 2cans would fill your system the molucles are larger and they also sells a system drier in a can plus a system sealer in a can....cost you about 50-70 bones

Experiments have been conducted to investigate the performance of hydrocarbon refrigerants in a hermetic vapour-compression system. It is shown that propane and propane/isobutane mixtures may be used in an unmodified R12 system and give better COPs than R12 under the same operating conditions.

I use it all the time. 1 14 oz can of Coleman propane, and 1 8 oz can of MSR IsoPro isbutane/propane fuel. Stay away from cheap stuff, they may have enough water in them to plug the expansion valve.

I have dumped it in on top of R12 with no problem. I've evacuated systems and recharged with this mix with excellent results. Leak detection is easy. Use your nose for big ones, a lighter and a fire extinguisher for smaller ones. The old style oil is fine. It doesn't leak near as bad as freon. If you have an automotive system that dies in a month, it'll probably go all summer on this stuff.

Usually I mix em up in an old freon tank, but sometimes I will just dump in a full can of MSR, then a full can of propane.

my 02
John

 

[Tim Frank]

Re: auto a/c r12 to r134a conversion

I use it all the time. 1 14 oz can of Coleman propane, and 1 8 oz can of MSR IsoPro isbutane/propane fuel. Stay away from cheap stuff, they may have enough water in them to plug the expansion valve.

I have dumped it in on top of R12 with no problem. I've evacuated systems and recharged with this mix with excellent results. Leak detection is easy. Use your nose for big ones, a lighter and a fire extinguisher for smaller ones. The old style oil is fine. It doesn't leak near as bad as freon. If you have an automotive system that dies in a month, it'll probably go all summer on this stuff.

Usually I mix em up in an old freon tank, but sometimes I will just dump in a full can of MSR, then a full can of propane.

my 02
John

Just don't smoke in the car....

 

[j_martin]

Re: auto a/c r12 to r134a conversion

Just don't smoke in the car....

Ok, so I'm carrying about a pound of compressed gas in a system designed for 300 psi under the hood, and 160 lbs of explosively flammable gasoline in a plastic box approximately 1 foot from the road, and whatever debris might be on it.

Relatively speaking, which carries the most risk?

BTW, a family I know lost half their children in a van fire caused by a piece of angle iron on the road piercing the fuel tank and sparking it off. They were all belted in for "safety", and the parents just couldn't get them all out. Actually there are quite a few fuel tank related casualties.

On another note, refrigerators in Germany have been produced with propane or isobutane for the refrigerant since about 1992. Tens of millions of them, and not one single safety incident related to the refrigerant.

BTW, pure propane is a dead ringer for R22 in performance.

 

[DECK SWABBER 58]

Re: auto a/c r12 to r134a conversion

I use it all the time. 1 14 oz can of Coleman propane, and 1 8 oz can of MSR IsoPro isbutane/propane fuel. Stay away from cheap stuff, they may have enough water in them to plug the expansion valve.

Propane does make an excellent refrigerant. As a professional auto tech
the problem I have with this though is flammability.

Anyone in business repairing auto a/c is required by law to recover
and or recycle any refrig. removed. You can imagine what could happen
sucking propane into a recovery machine with motors, pumps, switch's,
etc. Most shops were forced to buy refrigerant identifiers. This was
a big concern when R-12 was first being phased out, not so much
today I suppose since the # of vehicles using R-12 is small.

If you want to do this with your own vehicle it's your call. But....
keep in mind if your evaporater under the dash starts leaking
you could be in for some real excitement or worse. Their are
safer alternatives.

 

[j_martin]

Re: auto a/c r12 to r134a conversion

Propane does make an excellent refrigerant. As a professional auto tech
the problem I have with this though is flammability.

Anyone in business repairing auto a/c is required by law to recover
and or recycle any refrig. removed. You can imagine what could happen
sucking propane into a recovery machine with motors, pumps, switch's,
etc. Most shops were forced to buy refrigerant identifiers. This was
a big concern when R-12 was first being phased out, not so much
today I suppose since the # of vehicles using R-12 is small.

If you want to do this with your own vehicle it's your call. But....
keep in mind if your evaporater under the dash starts leaking
you could be in for some real excitement or worse. Their are
safer alternatives.

I put a sticker on the system:

System Charged with HC12A
ODP = 0
GWP= 0
Vent to Atmosphere

It's interesting to me that the expensive, flamable, poisonous when burned class 2 refrigerent R152A is EPA approved, while the class 2 refrigerent HC12A, which is cheap, flamable, and non poisonous is not approved.

On the leak under the dash, there is so much dillution air moving through there that if it leaks, it is immediately dilluted, and then if there's enough in the car to need ventilation, you'll smell a skunk. The concentration needed to ignite would smell so bad you'd be a certifiable moron to not evacuate.

In the same "it's dangerous" line of reasoning:
If you drive an automobile, you could get into an accident and be killed or injured, therefore we should make it illegal to drive an automobile.

just my 02

 

[windsors03cobra]

Re: auto a/c r12 to r134a conversion

Yes very diluted and if the Germans are doing it than more than likely its pretty good. Some pretty smart folks over there.

Horrible what happened to that family on I94, plenty of bad actors involved in that fiasco.

 

[Nandy]

Re: auto a/c r12 to r134a conversion

Guys, the discussion is interesting but it dont do me much good because the gasses and most of the specialized equipment needed are way out of the reach of the regular consumer. Interesting though... I would not worry too much about a small amount of propane since I have an 10 or 11 gallon of gas in my back seat...

yep your going to have to replace the rubber hemisphere seals on both the high and low side,lose all your charge...that's where most systems lose their charge from...If I were you I would look at using a hydrocarbon kit instead like duracool or redtex? 2cans would fill your system the molucles are larger and they also sells a system drier in a can plus a system sealer in a can....cost you about 50-70 bones

After looking much I found this tool that will let me do the change without having to evacuate the system. I seen it as low as $25 dollars which is probably more than what I would pay for gas but it will save me having to pump the vacuum again and go thru the process or filling it. More over, after much reading Im finding that the leaky valve issue is a very common one and the number 1 recommendation is to pull the cap on the port. I will test mine with soapy water and see if I can detect any leak with the cap. If no leak the I will just let it be. It would be interesting to keep my eyes open for a recycling machine in craigslist. Maybe some day they will make one that the regular joe can afford.

Here is the tool to change the valve:
http://www.acsource.com/valvecoreremoverinstallerpn91490.aspx

 

[Nandy]

Re: auto a/c r12 to r134a conversion

Still cooling!