AC not cooling that well and need R12

[thysonsacclaim]

If you can't see the dye, I would think it is either:

a) very, very small
b) in an area you cannot see

You may be able to rent an electrical refrigerant leak detector. I know places like AutoZone rent/lease their tools out, I just don't know if they have the correct type of detector. There is a similar detector here: TIF Instruments TIF5750A Refrigerant Leak Detector Scanner Type R12-. This one is for R12, but I believe there are some which can detect multiple gases. Find the leak and replace the part.

On the page for that it says it can detect leaks as small as .1 ounces per year, which is pretty tiny.

Failing that, I would pull a vacuum again, replace the hoses and o-rings and maybe even the receiver-drier, since it's fairly cheap. If you do it yourself, I would guesstimate it would cost about $150 or less for the two hoses and the drier. Doing that pretty much only leaves you with: the condenser, evaporator and the compressor.

EDIT:

I realized later I didn't entirely answer your question. I wouldn't add more refrigerant until you have fixed the leak first. I don't know about 134a not being compatible compressor, but if you have a leak, 134a is smaller than many gases and more prone to leaking anyway.

You *could* use canned leak stopper, but I have heard it is not good for the AC system. I don't personally use it and never have. It is best to replace the part imo.

If you can find a place that will rent the detector or if you buy one, I think youll be all set. Just make sure it detects the gas you have in there; I believe r406 is a blend, but I can't say for sure as Im on the mobile phone atm.

Hopefully you can find the problem.

[KenM]

Hey Franky,
                   
First of all, if you have a leak at the rate of 1 pound per day that's not a small leak, that's a big leak and you should have no trouble finding it. Forget those dyes, get an electronic detector and a bottle of soapy water, between the two of them you should be able to find the leak. Forget pulling any more vaccums until you fix the leak, you are just sucking air and moisture into the system. R406a is a blend, any refrigerant whose number starts with a 4 is a blend, so you will be losing its various component gases at different rates, meaning that at some point it's going to stop working and you need to pull the whole charge out and start afresh.
It occurs to me that you could have too much oil in your system and the evaporator is getting oil logged, meaning that the refrigerant is prevented from evaporating fully as heat transfer cannot take place due to oil coating the tubing internally. If you can drain the oil from the system and start again so much the better, not sure what oil R406a should have, could be a synthetic.

Good luck,

[thysonsacclaim]

That's a handy bit of info to know about the refrigerants starting with a 4. I didn't know about that.

[alabbasi]

I saw this video and had to chuckle because it reminded me of this thread

http://www.youtube.com/watch?v=ANtAbkKrOuI

[1980sdga]

It occurs to me that you could have too much oil in your system and the evaporator is getting oil logged, meaning that the refrigerant is prevented from evaporating fully as heat transfer cannot take place due to oil coating the tubing internally.

Good luck,

Good info. I never thought about that!

Whatever the truth behind the hydrocarbon CFC, ozone hole debate You can't deny that both sides have certainly stirred up a lot of passion amongst their respective denominations!

I'm using envirosafe 22 (R-22 replacement) in my home AC and it works well. We're having record high temps here and my old AC is working better than it ever has. Quieter too...

2 main dangers I see with using propane/butane in AC systems:

All the non-mobile AC systems I've been around use copper tubing which requires brazing components when replacing/servicing. The dangers to service personnel are pretty obvious in this situation when you have really flammable stuff in those pipes and the tech doesn't know it's in there!

Mobile systems use rubber hoses and gaskets which probably fail at a higher rate than a brazed copper system. (Sorry, I can't quote any Congressional panel/EPA test data but I'm sure I've paid for it  Feel free to consider funding one if you haven't already!) Plus it operates in a more confined (And possibly more severe?) space and blows air right at your head while you're operating a machine moving at 70 mph.

Just my 2 cents...

[alabbasi]

I paid $100 for a 30lbs jug of R22 a couple of years ago. While I agree that if you retail, you can pay through the nose , but there are still lots of private parties selling their R12 and R22 left overs. A little planning will get you the right product at the right price.

[KenM]

Wow, this is an old thread, interesting video you post there Al, I'm not going to rehash the arguments that have gone before here but I find it interesting that you guys in the US are finding R22 harder to

come by now, the amount produced is being cut every year and it will be gone soon enough but you can STILL get R12 over there, I just find this amazing. I met a fellow here just the other week who has

stockpiled several hundred kilo's of R12 against the day when it would be really really valuable but he has missed the boat, there is simply no use for it here anymore. There is the (very seldom) odd old car

that still has it's a/c not converted to R12 but there is just no further use for it. The same will happen with 22 but there are several more options around these days, so its loss is not going to be the great

disaster it seemed it would be 10 years ago. This thread also reminds me that Adam was quite ill and I haven't seen him posting for a long time, hope he's ok if still reading the forum.

 

[alabbasi]

Correct, this topic has been beaten to death already. I just found it comical that they demonstrated the dangers of HC refrigerants using a W116

[Casey]

Thysonacclaim: well, you almost made me feel guilty for going back R12 from 134a. However, that change produced r12 air that is definitely cooler than the 134a previously in my '78 280SE (not dramatic, but definitely noticeable). Alright, what about this Freeze 12---is it cooler than r12? If so, I'd be glad to try it. It gets terribly hot and humid in Texas this time of year, and I don't want to drive for 20 minutes waiting to feel any significant comfort in my car (compressor and receiver/dryer changed last year, evaporator less then six years ago); my wife won't even get in the car until October comes (Camry owner). I don't wish to sound snide; I just want to have some firm information on what might cool my car better than r12. Who is out there with real experience; I'd love to hear from Thysonacclaim again and anyone else. Thanks for reading my epistle. 

Don't feel guilty.  I'm an environmentalist saying that.  I also abhor Prius's.

The thing is you're using R12 that's already been produced, that is GOING to end up in  the environment one way or the other anyways.  It's recycled - if you didn't use it until it all leaked away some day, somebody else would.  Next time your A/C stops working well, then if prices have skyrocketed on actual R-12, then will be a good time to investigate replacements.  As an old boss said to me once about old chemicals, best thing to do is find a use for them and use them up!

It's highly questionable whether hybrid cars such as the Prius are in any way more environmentally friendly than their traditional counterparts.  There are very nasty environmental effects of the production of the batteries it uses, which won't last as long as your W116 has, and will cost more than a W116 to replace.  How will the old ones be disposed?  And it doesn't take much common sense to realize that driving the same number of miles in a year, there's a much bigger cost savings between 10 and 15mpg versus 30 and 40mpg - the former is a 50% difference and the latter is only 25%, but most people are brainwashed into thinking that the latter is a bigger savings.  Plus, simply keeping old cars on the road longer is ALWAYS more environmentally friendly, even if they are gas guzzlers, because then less new ones are being produced and shipped worldwide.  You as the consumer will spend FAR LESS money long-term keeping an old car in perfect shape and on the road forever and fed with fuel than you will by trading in for the latest "green" trends every time something new comes along.  Maybe electric cars will actually make some sort of sense some day if we're not producing the bulk of our energy via coal, oil, and nuclear.  Plus, it's loads more fun to drive a W116 than a Prius.

So drive your W116 as long as you can!  Use recycled R12 as long as you can!  Do it right and get it done at a certified place that collects escaping/old R12 rather than attempting to DIY.  If you need more miles per gallon, invest in a MegaSquirt system or swap in a diesel engine that would go to waste.  Don't feel bad at all about it - enjoy the drive!

[Casey]

I saw this video and had to chuckle because it reminded me of this thread

http://www.youtube.com/watch?v=ANtAbkKrOuI

  How DARE they treat a classic Benz that way!!

[thysonsacclaim]

Leak rates:
One thing to point out without rehashing old arguments is regarding mixtures. These are governed by Graham's Law [ http://en.wikipedia.org/wiki/Graham's_law ]. What this says is that a Gas A will effuse at the inverse square root of the molecular mass of Gas B and Gas B will effuse at the inverse square root of the molecular mass of Gas A. lease keep in mind that Graham's Law applies to effusion through a HOLE without any molecular barrier. That is to say, through the vent nozzle or a large hole in an AC system. The actual leak rate through a semi-permeable membrane, like a barrier hose, is a lot more complicated to calculate and is also a lot slower in comparison and progression; in other words, provided the chemicals are nearly the same size, there is no problem. There is also no problem, generally speaking, if the smaller molecule is the one carrying the oil since the oil will attach to the compound via a weak molecular bond and thus reduce its effusion rate.



Explanation (shrunk for those not interested in the specifics):
Take hydrogen (H2) and oxygen (O2) and mix them together. Hydrogen [H2 form] is ~2 grams/mole and Oxygen [O2] is ~32 grams/mole. The math dictates that hydrogen will leak at a rate four times faster than than oxygen (this is the Wiki example). However, many blends (regardless of composition) try to use gases which are of similar molecular weight.

So for the HC-12a blend (only using this one as it was most recently discussed, but this applies to all coolants and gases in general):

The ratio is [~7.61]/[~6.63]≈1.159, meaning there is a difference of ~.16, or 16%. That being the case, if there were 16% more of the amount of the faster leaking gas, the ratio of the gases would effectively stay the same because both gases are going to leak at a constant rate. Thus, you could top it off without having any problem. I would assume this is the case with many of these blends (again HC, or not HC), because in some, like HC-12a, the isobutane I am fairly certain acts as the oil carrier. If in doubt, and your cooling system is free of leaks, you can always completely evacuate the system and do a fresh fill, which won't hurt anyway (again, as Al points out, this is trickier for HCs and will be trickier for the newer non-HC refrigerants coming out until they become more mainstream.

So, as a rule of thumb, if the division of the ratio comes very close to = 1, the difference in effusion rate is going to be very, very small and it would take a long time for one gas to completely effuse out of a closed system and become completely unbalanced. Not all manufacturers specify the blend percentages (or even if they are a blend!), so if you're worried, look for the coolant's MSDS, the coolant number if it is a coolant with a trade name (like R290, R12) or call them. This is important whether you are using a HC coolant like R290, or blends of CFC/HFC/HCFCs, like R410A (aka Puron, a 50/50 blend of R-32 and R-125).


Future of R134a:
I would also like to point out that R134a is going to be phased out very soon. Starting in 2014, I believe, GM will be using HFO-1234yf and it has been given the green light in the EU and I think is now in newer cars or will be very soon.


Best Approach (IMO):
While R290 is considered a direct drop in for R12—meaning it has complete compatibility with those systems—it is not legal in the US as a SNAP replacement for original equipment originally charged with R12 and without modification to the aforesaid. It is, however, superior in cooling ability, compressor workload, but works best in R12 systems vs R134a systems (which is the bummer part about the EPA's SNAP regulation). The flammability is there, but I personally don't think enough adequate, thorough, real life scenario studied have been done to show it has a much higher risk than some other coolants in common HVAC/MVAC use. But, for the average Joe: [134a]>[Alternative, legal acceptable HFC/HCFC blended or unblended]>[R12/HFO-1234yf*]>[R290]. I'd consider R290 only for those who know what they are doing, have taken MVAC classes, and have ensured their system is in very good or (preferably) brand new and is legal to use (ie not in a system now considered to be an R12 system).


HFO1234yf use & safety:
It's not terribly flammable, but you can see the propagation of flame and several of the other tests indicate that while it usually won't cause a flash explosion, it will cause a smolder which will cause a secondary fire, unlike a flash explosion. Although with those videos above, I'm not convinced of the validity of them either. My German is very poor and the other just shows gas ignition.

On the safety side, it is less flammable than R290 et al. However, it decomposes into hydrogen fluoride, which has a rigorous free radical Fluorine that causes breaks in DNA and, in solution, is known as hydrofluoric acid. Because of this, it is handled in inert, polymer chain plastic containers. It's very bad to get on you. Think bad acid burn, but then imagine massive, electronegative Fluorine atoms running through your blood stream cleaving off bits of your amino acids. Not good. Again, this happens on decomposition (burning).

It is a flammable gas, and early attempts to mitigate this by using a combustion suppressing chemicals were met with squinty eyes and caused health issues to those handling it. The oil is different from 134a's; it is NOT [yet] considered a drop in replacement, but rather a near drop-in replacement. The oil used for HFO-1234yf has also show some corrosive effects on aluminium, and will require new shop equipment and training to handle. Given all that that, I do think it is probably superior to R12, R134a, and R290 (all based solely on safety and environmental friendliness, I do NOT know anything about its actual cooling properties at this time). In terms of price, that is where it will be a downer.

Videos of HFO-1234yf: http://www.youtube.com/watch?v=yf1NpY9qIY8 , http://www.youtube.com/watch?v=ujmo-P5KdQ4


Personal Thoughts:
Personally, I think CO2 would have great potential and I do believe the pressure issues could be easily mitigated using new technology. And it's a flame retardant! But I don't see that happening because there is no money to be made. It's simply more cost efficient to product new HFCs, CFCs, HCFCs, HFOs, etc. The actual chemical is patented in some countries, although in others only the specific chemical chain reaction they used to produce it is patented (and usually there's more than one way to skin a reaction  )

As for the video, I find it comical because it, as the reporters state, is far from scientific or 'real' world but indeed ironic that they use a 116! No one is going to drive around with a spark plug hanging out of the block without some serious issues to begin with and I don't see any other means of it coming into contact with it. They gloss over this of course so I guess we don't know. I could drive up there and ask, though, it's very close to me! What I'd like to see are crash tests with HFO-1234yf, HCs, and CO2 as well as the real world cooling. I simply wish more research was done regarding all of these products and I feel that all too often the consumer takes a back seat in terms of cost, valuation, choice, and so forth.

So keep in mind that 134a also has its days numbered, 1234yf will likely be phased in and (until we get a new oil, if that happens) will not be able to simply be dropped in an existing 134a system without complete evacuation, hose change, etc (which is good to do anyway). Maybe one day we'll have something good for everyone involved 


Thanks for the vid!


*When available and with new equipment

EDIT: Fixed typos, clarified, and condensed and sectioned to allow one to browse to the topic they're interested in.