A/C question
 

Recharge day.

Which side is the Low pressure Which side is the High pressure?

Is the low pressure the COLD side and the High pressure the HOT side when the A/C compressor is running???

If you are not trained at working on A/C you might want to leave it to the professionals.

I just had a very good friend taken to the emergency room when he was fiddling with a A/C hose and it burst on him. Got a full shot of gas to the face and blinded him for a while. This system can hurt you if you make a mistake. He was out of work for a week over this...

The high pressure side is the one coming out of the compressor with the smaller tubing or hoses. Low pressure side is the one coming out of the compressor with the larger hose or tubing.

ALWAYS USE GAUGES IF YOU ARE NOT 100% SURE OF WHAT YOU ARE WORKING WITH! Hooking a freon container up to the high side will turn it into a hand grenade. They are well known to explode if not done correctly.

Not trying to scare you but do not need another person going to the ER over A/C repairs.

The low side gets cold and the high side gets hot. I agree with Joe that you better have a good understanding of what you are doing if you intend to mess with the AC. If you are just a bit low on refridgerant, a recharge may be the ticket (assuming it still blows "cool" and it has been awhile since a recharge), but you still should monitor the pressures as you top it off, otherwise you wont know how much to put in. I fixed a leak in my '79 SC and recharged over 1 year ago with 134 and it still is working fine, but I did have a vacuum pump and gages to use.

Re: A/C question
 

Joeaksa has pointed out some good warnings for you.

But, to answer your question: in a normal running system, a/c system on (both center floor console knobs turned fully CW... to the right),
engine running, and <b>engine deck lid down</b>:
..... we'll take you to a safer area to fut's around here: if you open your front trunk, pull back your carpets and open the trap door (aka "smuggler's box") you will find the evaporator box. On the driver's side of the cavity (LH side when sitting in the car) you will see two rubber hoses, the smaller diameter one with the 45 degree fitting connecting to the expansion valve, which has a round "hat" on the top and a few copper coiled tubes coming from it. This line coming into the valve is from your receiver drier. This is going to be the liquid high side line. With the system running this line is usually warm to hot.
Just below the valve is a larger diameter rubber hose that has a 90 deg fitting attached to the evaporator outlet.
This is the low side of the system.... this hose runs back to the suction side of the compressor. This pipe or hose connection should be cold ... usually sweating. And, if the system is running very well you'll find back at the compressor the fatter suction hose Joeaksa mentioned will be cold or sweating too (watch out when you poke around the engine pulleys when the thing is spinning, I saw a fella lose a finger one day).

And you have the receiver drier located against the back side of the driver's LH front wheel well. With "floating ball " driers and R12 the system is "about" full when the refrigerant floats the ball just about to the top of the round site glass. With simple non-floating ball site glasses its full when the glass gets full. With R134a you don't use the site glass but rather you use the P&T or Pressures and Temperatures method of charging which is more accurate for overall system peformance...... which leads us to the question.. Do you really want to approach this job or would you rather be cutting the grass? Not trying to kill a fun day for a DIY project its just that some DIY projects require more tools and working knowledge than others.
2 cents.

Search around Pelican here and you'll find lot's of reasonable posts for the DIY on a/c. But at Joeaksa pointed out.... sometimes, for the once in awhile ac recharges it simply is not economical to pursue, but you can have some fun chasing the problems.

cool, thanks for all the info. One more question....

I was told by a HVAC guy that you can mix R12 and R134a. After reading a few sites, It would appear that only in USA you cannot legally do that. But physically it is fine

Am i correct?

pmajka..please wear good eye protection at a minimum..and long sleeves, etc. that will help protect exposed skin. i've also known of someone badly injured fiddling with theirs. i just don't mess with a/c anymore unless the system is already discharged. r12 and r134 are different size molecules..don't know of any advantage to mixing these.
ryan

Do NOT mix these two gasses, they are totally different. I could care less about legally, these two gasses are not to be mixed. As well the oil needed for a R134 system is not the same as the oil used with a R-12 system. Legality is one thing but compatibility is another.

It needs to be one gas or the other.

Also, Kuehl does A/C work for a living and knows what he is talking about. He also builds several systems and add-ons that make the 911 A/C system work much better, so he is a good source of information. I am a trained aircraft mechanic and pretty good at A/C but this is his world.

thanks again for the info...i always ask here at Pelican before touching the car. Think i am going Enviro safe. will have to delay AC till next week..

I have used ES-12 for years on my cars and have no problems with it. Am not going to say anything more as I do not want to try to influence you one way or the other but no matter which gas you use in your A/C, pls either know what you are doing or get someone who does to help you with it.

My $.02

Listen to Joeaksa... He knows what the hell he is talking about!

Quick note to add that I haven't run across here Joe...
After running almost a year with spectacular performance of the ProCooler r/d and Industrial ES12, my cooling was not quite up to par this summer season... Most likely to the original refrigerant hoses still being in place. You know, the ones with microscopic pin holes...

The refrigerant charge was slightly down... I mistakenly thought that by just topping off the system with more ES12 woould do the trick.... It made no difference... Brad form Redlands told me to evacuate the system, and put in a fresh charge... Lo and behold, I actually read the instructions on the can, and it said the exact same thing! I did it, and the performance has returned. Something about there being a specific mixture for ES12. Only a certain portion of that mixture escapes through the pinholes, and adding new messes up the exact combo of gas? Eventually, I will step up and purchase new barrier hoses, and that should eliminate the issue... However, for $18 to fill up an empty system....

One thing that Patrick mentions is the molecule size and pin holes. R-12 and ES-12 are about the same sized molecules I believe. R-134 is much smaller in molecule size, so if you have the original hoses and system it tends to leak out faster.

ES-12 is different from the other gases. In the old days we would shoot R-12 in the system until you did not see bubbles in the sightglass. Cannot do that with ES and have to go by weight. Also if your system takes 3 pounds of R-12, it DOES NOT take 3 pounds of ES. Talk to who you buy it from, they can help you here.

yep..take it from a guy with a degree in organic chemistry here..what joe says is true - r-134 is a much smaller molecule and thus far more prone to leak out of the original non barrier-styled hose. if you don't have barrier-style hose and wish to upgrade to r134, consider this upgrade even though the recharge cost is much less with r134.

btw, welcome to the '5-figures club' there, joe.. :)
ryan

joe, pat, where did you buy your ES 12 and

How many cans to fill up an evacuated system???

This is EXCELLENT advice.

Autorefrigerants.com

Per Joe's suggestion, I used the advanced industrial ES12a.

2 to 2.25 cans should do it...

Per the sticker in the engine compartment of my car, R-12a capacity is listed at 39oz.

6oz. of ES12a is equivalent to:

16oz. of HFC-134a
18oz. of CFC-R12

Ryan,

Thanks and did not realize that I was over 10k posts until just a bit ago!

Glad you have a degree like this, its hard for me to to fly airplanes for a living, let alone work with chemistry formula's!

Got the first batch off of Ebay then found a guy locally here in Phoenix. Easiest to look on Ebay or do a google search and you will find it.

Patrick covered the amount you need. I would buy 4-6 cans and that way you are covered for a long time.

well, as you know, joe..i miss flying the lear like crazy. a decade in aviation and it still stings to be apart from it. i flew commercially on southwest these past cpl weeks to spend time in new hampshire with my gf for the first time in several years. i cannot tell you how emotional it was for me to be sitting there and staring out the side windows for a change. on the way back, at night, i could still identify al the major cities by the runways as we'd pass over. hurt.. :( enjoy it, soak it all in for me, buddy..
ryan

If you review the EPA's website and locate the SNAP approved and disapproved refrigerant list,
start here:
http://www.epa.gov/Ozone/snap/refrigerants/macssubs.html
other reading material
http://www.facm.umn.edu/BAS/refrigprogram/FMRegRefrigerantPolicy.pdf

you will see some brands are a combination of different refrigerants. The question is how much of this or that makes a working combination. If you intend to shoot in some "X" brand or type refrigerant to make up a low charge of "Y" refrigerant..... you can run into problems related to pressures .... which leads to trouble when you try to diagnose a problem and mixing refrigerants is a "no no" (legal or otherwise) especially when you take the car to a service facility and they don't know what you did and they evacuate the mixture and it contaminates their recovery machine .... this tends to get the facility owner really annoyed, so don't bother doing it.

With regard to refrigerants other than R12 or R134a, our focus is strictly those two types for various reasons. So I'll leave the discussions regarding the other refrigerants to the peers here.

Let me know if you need help otherwise and we'll see if we can resolve your issues.

The day is done. Time to throw the dog in the pool and rough up the kids.

Enjoy your weekend.

I could not help myself. I had to post this picture again.
What a pisser!
Understand, this is NOT a promotion for fire extinguishers however I'd love to get the copyrights on the shot.

http://forums.pelicanparts.com/uploa...1153090323.jpg

Look at all those guys with teeny tiny fire extinguishers. How long was that car on fire for all these people to go over and show up with cameras and stuff, and why didn't anyone go grab a hose?

"why didn't anyone go grab a hose?"

Maybe they understand propane/butane fires. Water is not very helpful for a fire fueled by leaking propane or butane. Below is an excerpt describing firefighter training for liquid propane fires:

Most people have seen their gas grills flare up and all you get is burnt meat. But with a liquid propane leak you better call the fire department.

Columbus Acting Fire Chief Bill Kluetzman says fires fueled by liquid propane leaks are becoming more common. "A lot of propane fires on gas with campers, gas grills, houses being heated with propane the big 250 gallon tanks outside their house."

40 fire fighters from 7 departments got a first hand lesson in how to deal with different scenarios Wednesday night.

It's not the same as a structure fire. "The main difference is the fire doesn't go out. You can put on it all the water you want all you're doing is redirecting the flame of a gas leak," says Kluetzman.

The key is to shut off the gas. The water forms a protective V, redirecting the flame while the man in the middle reaches for the valve.

"As they walk they watch the middle of that V and they'll see the valve appear behind the water stream. At that point once they see it they can reach in. What they want to avoid is reaching through the water prematurely to shut the valve off," says Bob Goplin, an instructor for Fire and Industrial Response Enterprises.

Even the training is dangerous, because both hoses have to keep together. "You got one group that goes a little ahead of the other and you got a place where fire can break through it," says Goplin.

An exposed fire fighter doesn't have very long. "If they're in there for any longer than just a few seconds it's going to deteriorate their gear and give them fairly serious burns," says Goplin.

The training is timely, because all the fire fighters saw the damage caused a propane leak in the Fall River home explosion and the fatal explosion caused by a gas leak in Ellison Bay. "It brings this type of school a little more to real life," says Kluetzman.

Can anyone confirm the cause of the fire in that 928?

Patrick,
The flames are burning refrigerant. You can read the how's and why's here:
http://www.imcool.com/articles/aircondition/Porsche_928_Refrigerant_Fire.htm

I had alike problem with my first 1978 928 when the clutch slave hose broke and sprayed fluid on the exhaust header, nice little fire but it snuffed itself out as soon as the fluid stopped flowing.

The bottom line is the that the refrigerant "system", unlike the fuel system in most cars, is NOT specfically designed to withstand or avoid damage or losses which could allow the refigerant to be exposed to ignition sources. For instance, if you have an evaporator which leaks, in most cases the refrigerant enters the cockpit through the vent system. If you have an ignition source in the cockpit and the AFR's (air fuel ratio) are good you can have fire.

Last week I located the source of a refrigerant leak for a friend in his wife's late model Buick. It was the evaporator. Our electronic leak sniffer was beeping like crazy. I showed the fella and the first thing he said was "gee, I could not smell any refrigerant, is my wife breathing that stuff in?".
"Well, YES, she is for sure. Do you want to the read the MSDS (material safety data sheet on the stuff ?"

The same is true for the condenser in the front of the car (ie. 924s, 928, 944, 968, 996+) or a deck lid condenser in a 911/930. If you have a leak or an "accident" and the AFR's are just right and you have ignition.... POOOF!

And if someone wants to argue a point that "well, gasoline leaks can happen in an engine compartment too, so how is it any different than a flammable refrigerant?" Simple.
You can smell the gasoline, you can't smell the refrigerant!


In the picture of the 928 on fire, what led up to the fire (a poor hose layout) was a series of faults or small accidents perse. In either event it did an it can happen.

Given all the various types of SNAP approved refrigerants we can play with vs. those which are dangerous under particular conditions or faults, I simply would prefer sticking with something that was a little less...... ah, exciting!

Take it further in terms of common "cents". Say a car owner wants to save some bucks on improving the performance of his ac system in whatever make and model car. So he hears about a new refrigerant called "colder than ice", it's cheap too! Though it contains flammables and has been used for years, and all his buddy's are using it without any problems, he decides to use it. Heck, he just saved $1,000 bucks in normal conversion parts or recommended improvement parts. However the new refrigernat he puts in his car catches on fire (for whatever reason and I won't go into the "but if he did the job right" argument). He has a $500 or $1000 deductible on his insurance policy and who knows if they will cover the loss because he is using something that is not approved. Did he save any money in the long run? Oh, but wait a minute! The manufacturer of the flammable refrigerant "guarantee's their product 100%". How many letters do you think it is going to take for him to get reimbursed? Do you think the refrigerant company won't argue a case of negligence. Just a 2 cent point. I am not saying you should not try something new or novel. Just be aware of what you are doing.

i seem to recall that 928 fire happened to a member here a year or two ago..iirc. ;)
ryan

R-12, the "approved gas in our A/C systems" combined with fire create phosgene gas, the stuff that was used to kill thousands in WW1.

Lots of things in these cars that will kill you. Personally I am more afraid of the 20 gallons of fuel sitting on top of my legs but then I have been in a gas fire and have lasting memories that I do not need nor want to repeat.

I personally have never heard of a fire caused by any A/C gas (other than the photo above and who knows the real story on what happened there) nor anyone whose claim was not paid due to a "non-standard gas" in the system. As well have never seen a post on Pelican saying that this has happened. It might have happened in the past or could happen in the future but who knows.

So the propane/ butane powered 928 caught on fire, after the refrigerant caught fire?

I had a fire in my 356 cab. The chemical fire extinguisher did it's thing, a short puff of powder, then the fire got going again. I put it out with a lot of water from a garden hose. The only damage was one of the fuel lines that broke, and a lot of smoke related cosmetic damage.

Thats my issue with this photo. Have seen several people tout this as a "propane mix" fire and it would be really nice to prove that the car was using this mix and it caught fire from this mix before posting it all over the internet as such.

R-12 and R-134 gasses are also flammable but most do not want to talk about that. There are many things in these cars that will kill you, driving being one of them.

"R-134 gasses are also flammable"

Not by rigorous definition - good luck trying to get R134a to ignite in the open air. A jet of it tends to blow out the ignition source. I also seem to recall it is used as a filler/carrier gas for medical anesthesia purposes.

Don't confuse auto-ignition temperature and flammability; they have significantly different meanings.

Joe, Jim, Kuehl.... Words all well said!

Each of you have made VERY valid points.

Thanks for the link Kuehl, as the play by play of the smoking 928 is invaluable...

That said, if I was willing to take the same shortcut, and willing to take the same ridiculous risk that the 928 owner did with using a low pressure hose 3" too long, forcing it into an un-natural shape to make it fit, leaving it almost touching an electric radiator fan only held back by a few plastic zip ties, I guess I would have whatever comes my way too...

Of course, a similar scenario could unfold, if I was rear-ended, and my condensor was damaged to the point of leaking..... That is a risk I'm willing to take... My curiosity lies with the possibility of a similar fire/explosion if the original R-12 was used.... And what about R134a?

Kuel:

I took your advise a few weeks ago and went with straight 134a without the "o ring conditioner" on my recharge. I remember the ac service guy who worked on my condenser mentioning that you can't mix refrigerants (as you posted also). I was wondering, as long as I buy 134a, does it matter what brand I buy to do future recharges? Or are you talking about no mixing R12 with 134a (I would never do that, they are clearly not compatible). You mentioned that the issue was working pressure differences.

Oops, Kuehl. That pesky h always gives me trouble.

"My curiosity lies with the possibility of a similar fire/explosion if the original R-12 was used.... And what about R134a?"

Look up the MSDS (material safety data sheets) data on-line for R-12 and R-134a. Again, good luck getting R-12 or R-134a to explode or burn in the open air (STP atmospheric conditions).

IMO, the major hazard is breathing the decomposition products (very bad stuff) from the exhaust pipe after either R-12 or R-134a have been inducted into an engine and burned.

Both R-12 & R-134a are nonflammable. Phosgene is a decomposition product of R-12 only when it's exposed to the right temperature range.

Also gasoline is most certainly flammable, but you can't run the car without it so you have no choice. It's also contained in a system that was designed with the fact that it's flammable taken into account. Of course there is always some risk.

The AC system on the other hand wasn't designed to handle a flammable material and they are notorious for leaks. Of course that doesn't automatically mean you ARE going to start your car on fire - only that there's a higher risk it might happen. As long as you're aware of the added risks and willing to accept them by all means go for it. I'd be willing to bet the person who used it & neglected to make sure the hose wasn't close to the fan blade hadn't thought through all the risks.

Personally, I prefer to make my AC system work with 134a, although it means it will have to be modified, for several reasons:
1. Sooner or later R12 will be NLA
2. With the right equipment it does work very well in a 911
3. It's the industry standard so I can have it easily serviced
4. The non flammable blends don't appear to work any better then 134a. In fact most of them are a blend of 134a & something else. http://www.ackits.com/testresults/alttest.pdf

But that's just me.

Joe,

1) The source of the picture was posted in this thread,
I'll repeat it again if you missed it:
http://www.imcool.com/articles/aircondition/Porsche_928_Refrigerant_Fire.htm

2) If you view the article at the URL you can read:
A) when it happened,
B) who it happened to,
C) what the source or fuel of the explosion and fire was,
D) the series of "events" or little unexpected accidents (just trivial stuff that could neeeevvvver happen to us, right!) that lead up to the explosion and then fire,
E) commentary by the car owner and bystanders

3) The picture and story have already been posted all over the internet. I was skeptical too, seeing it for the first time, but I enjoy reading in depth so I'm over the shock.

4) Could it happen to another car owner using a refrigerant that is prone to burning more than the SNAP approved refrigerants? Maybe. Maybe not. However it is easy to sit on the side line and say "that will never happen to me..... because......"

5) Are there other cases of refrigerant fires. Who knows?
Maybe the topic should be covered.

However take what the EPA states with a grain of salt or take it as logical advise (and believe me I'm the first to question Big Brother):

<i>Flammable refrigerants pose a special challenge, because air conditioning and refrigeration systems in the US have been designed to use nonflammable refrigerants. They are not designed to protect users, service technicians, and disposal personnel from the possibility of fire. Therefore, the use of flammable refrigerants in existing systems may pose a risk not found with nonflammable fluids. </i>
http://www.epa.gov/Ozone/snap/refrigerants/hc12alng.html

I have never reviewed the "spec" sheets or <i>certificates of compliances </i> from various brand names peddling R134a. I would assume they all meet a certain standard. Most of the time we use Dupont or Interdynamics. Most of the time we use only virgin refrigerant; evacuated refrigerants are sent to recycling.

I would not recommend mixing R134a with R12 or any other combination of refrigerants; as stated before for the <b>known</b> various reasons: legal, pressure issues, and the poor shop who evacuates out a mixed blend without knowing.

Ok, we have proof that one car in the country has had a problem. Unfortunately it was due to stupidity, then compounded by the ES-12. Guess its time to stop using it for every car in America because of one idiot. Thats what the FAA would do and I work with them every day.

Kuehl,

Thanks for the link, and no, I had not seen that URL.

I have used ES-12 for over 3 years with no problems on many vehicles. Will probably continue to do so. Will also continue to carry a fire extinguisher in every car and hope they are not used.

The rest of you guys can do as you wish.

I actually think the greatest fire risk for 911's are the fuel hoses; there are a lot of them out there with the original rubber fuel hoses still being used. It is frightening to remove a braid covered rubber fuel hose from the system and have it snap in two in one's hands like a piece of dry macaroni. :eek:

Joe,

I think the point of the post was to bring to light that it takes a series of events, what I call "small accidents", which can lead to "a big accident". And, many users of a given product, flammable refrigerants which are oderless and colorless in this case, may not be aware of potential problems inherent with its use or the warning.

Like cigarettes, we see the label on the box that says "The Surgeon General's Warning: .........blah". Those who do continue to smoke enjoy it for various reasons, or are addicted, even though science and history have proven the pitfuls of smoking. I'm not saying that using a flammable refrigerant is addictive here, I'm saying that enjoying the use of the refrigerant and forgetting about the series of events could lead up to, well, big problems as in the example of the Shark owner in the Chariot of Fire article.

Someone posted a note about the byproducts produced by R12 when exposed to an open flame. I experienced it first hand and I was a kid and "aware" of the <i>series of events</i> which lead up to it;
briefly I was stuck in a closed garage on a very cold winter day, running a kerosene heater (many of which are illegal today in some towns and states), I had to disconnect the ac lines on my Audi Fox prior to pulling the engine, I broke the lines and the refrigerant gas filled the garage, I noticed the kerosene burner flame start to "fizzle", less than 30 seconds later my throat felt like I swallowed acid, I could not catch my breath, luckily I made it to a door and fell outside. Today, not yesterday, we know why you should not do that. So it was a series of small events played upon me when I was naive, that almost caused a major disaster.

Statistically flammable refrigerants are undoubtably on the bottom of the potenital disaster list of freak accidents.
A very reasonable report by A.D. Little in 2002 somewhat points out the odds of a flammable refrigerant fire as being rather nill, however they, like the EPA suggested, state that <i>"In view of the greater risk for collisions of motor vehicles (than for stationary equipment) that could result in damage to the areas of the vehicle where air conditioning system components and tubing are installed, the question of fire safety when using a hydrocarbon refrigerant requires careful examination." </i>
http://www.arap.org/adlittle/5.html

Jim suggested that a fire or accident is more likely to result from fuel. In all likelyhood that is probably true. BUT, there is a greater likeklyhood that you will have the opportunity to "smell" the gasoline and do something about it as opposed to not being able to smell a flammable substance that has not odor; such is why a fragrance is found in natural gas.

Though I respect that you work with the FAA I don't agree with what you might feel the FAA would do. As you know, since TWA Flight 800 went down off Long Island nearly 10 years ago, ALL the <i>series of events</i> have not been resolved. Yes, the wiring issues are being corrected but the residual problem has not. Why? Cost. Simply a matter of cost. And the FAA has its hands full. There are not enough inspectors or time in the day. I can tell you first hand as I had "worked" alongside the FAA for many years and I setup and ran a Repair Station myself. And I can tell you first hand that there are a heck of alot of 737's, 757's flying above you that share a common part in the thrust reverser system used on a specific engine, of which I believe may not had been tested correctly by the OEM (demonstrated to them first hand) .... because of a "series of events" misled the mechanics and OE inspectors to believe what they were reading was factual when in fact it was totally incorrect.


<b>So pmajka. I appologize for stepping upon the box and and playing the village screamer. Did you ever get your a/c working?</b>

Still waiting on the Coolant to arrive via FEDEX.

Well after reading this thread, i started doing more reading on the subject else where. I can do the Top off with someone assisting, but with educating myself, i feel better about it. I will have a fire suppresant available, just in case.

I will go to a professional for a full Evac later when i have some time. (in the fall maybe).

A wise man once said, "if ya dont know what you are doing, STOP. Dont Shotgun the job."