a/c conversion kit

Eldorado · 06-07-2005, 09:52 AM

has anyone tried conversion kits like this one?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4554588633&category=35625

just wondering - I dont wanna shell out the extra cash for the R12 if I dont have to.....

Eldorado · 06-08-2005, 09:07 PM

anyone?

I've heard mixed reviews...

user426 · 06-09-2005, 10:31 AM

I'd like to know also.......

livewirevoodoo · livewirevoodoo's Garage

I just called a shop earlier and got a quote of $80 for a refill with R-12. Not that much to be saved by the conversion in that case.

In discussing the conversion with said shop, the guy mentioned that the R-134 is at a higher pressure and puts more of a strain on the compressor? Any validity in this?

Eldorado · 06-09-2005, 01:24 PM

yea I heard it too (the higher compression) - which is why you dont use *as much* R134.

R134 is cheaper - and is just as effective... but you're right - it probably isn't worth the risk... if this is (most likely) the one and only time I need to refill it for the next few years - it's probably a worth while investment..

Eldorado · 06-09-2005, 01:43 PM

I just called around to about 10 people licenced in the Toronto area to do AC work on cars... 4 of them told me they wouldn't refill with R12 anymore because it's illegal (which I really dont think it is..), and the other 6 quoted me a couple hundred dollars to refill it because they would "legally need to check for leaks" first....

anyone have any suggestions? *confused*

lm6y · 06-09-2005, 05:06 PM

Eldorado, It's really pretty simple to do a R-134a conversion. But, it's a little more difficult to do it right. At the VERY least, have the system vacuumed down to reclaim any of the R-12. They don't make it anymore (other than Mexico, and similar countries), so what's out there is all there is ever gonna be. Pulling a vaccuum also dries out the system.

To do it right, you will need to disassemble the system.

Change the O-rings (because if they don't leak now, they will eventually will with the new oil, and the new pressures).

Flush all of the components EXCEPT the expansion valve, to remove all of the old oil. Mineral oil from R-12, and PAG or Polyol Ester oil from R-134a don't play well with each other, it will cause problems later, although polyol ester accepts mineral oil better. The Mineral oil won't be carried by the R-134a, and will eventually settle to the lowest point, which is the compressor. We all know liquids don't compress.

To flush the compressor, remove it, and pour very small quantities of the oil you will be using into the intake side of the compressor, and spin it BY HAND. Run probably about a pint of the new oil through it, and be sure to get as much oil out of it as you can so you won't have too much oil in the system.

Change the Drier. If it has never been changed, it's at least 15-20 years old, the drier removes moisture (that's why it's called a drier, slick huh?) and it is the only filter in the system. It traps impurities by gravity. Every system will have something in the bottom. Moving parts do wear out, and since it's a sealed system it settle in the drier. Moisture is THE most destructive thing to a A/C Sytem. All there is in the drier is a dessicant bag. The bag can deteriorate after a while, and circulate dessicant beads throughout the system causing a catastrophic failure. Most of the time, all you can do is replace EVERYTHING but the hoses. The dessicant gets trapped in the passages of the evaporator, and condensor coils, and can't be flushed out, except for the hoses.

Put the system back together using whatever oil you will use on the system to lubricate the O-rings, and pour it in the high side line. You don't really need barrier hoses, as the old oil soaks into the inside of the hoses creating a "skin". Have the system vaccuumed down to remove as much moisture as you can. Lowering the pressure of water raises it's boiling point. Have the system pulled down for at least half an hour. If it holds vaccuum for at least 15 minutes whatever leak is there, probably isn't that big. Best to see if it holds for a few hours. It probably won't, since the Nippondenso compressor used on these cars are notorious for leaking around the front shaft seal. That's the bad news.

Then you are ready to fill with manifold gauges on the LOW SIDE ONLY! Don't use the cheap little gauge that comes with the kit. It will monitor the low side, but if there is a restriction in the high side, the low side will still say it's low, while the high side keeps climbing, as you keep trying to fill it. You won't be able to tell this by the little cheapie gauge, untill the high pressure side blows up in your face.

That's all there is to it!

The common misconception is that R-134a doesn't cool as well. That's the exact opposite. 134a removes heat better, BUT the r-12 system isn't big enough to handle the heat load. Freon doesn't cool, but "unheats" the air blowing over the evaporator coil (inside the car). R-134a can remove so much heat that the condensor (in front of the radiator) can't get rid of it all. That's one of the reasons for the higher head pressures. When you heat a liquid, or a gas, the pressure goes up. Think of a 500hp Big Block engine on a Geo Metro radiator. The little radiator can't handle the heat load. This is also why you don't open a hot radiator. The heat has raised the pressure, and it will spew all over the place. When it's cool, it doesn't.

I'm not a fan of some other refrigerants. Some have butane, or LP gas in them. It seems like if you compress flamable gasses, you have a bomb waiting for a place to happen (like a front end collision).

I'm sure there are a few people here that are going to disagree with almost everything I said, but I will stand behind everything I have said. There are ways to do things, not all of them right, but this is how I have done a few hundred conversions, and how the reputable A/C shops recommend, and haven't had a problem since with any of them, other than ones that were just worn out, and couldn't handle the load R-134a puts on them. But I warned them in advance. Some people just want to be cool now, and don't think ahead.

I hope you know more about it than you did, and I hope it helps you out!

Eldorado · 05:32 PM

I totally understand what needs to be done, but the matter of me actually doing it is secondary - I'm not all that good with a wrench and I'm just starting to learn...

quick question - how would one go about draining the existing R12 out of the system?

you're right - I "just want to be cold now.." lol it's friggin hot driving in 35+ degree (celcius) heat with no a/c.... and my hours got buggered up over at payroll this week so I only got paid for one shift instead of 9.. (grumble grumble) so I might have to wait another 2 weeks to get paid before I can afford the "couple hundred" to get someone to do it for me..

unless there is someone that knows someone in the Toronto area that could help me out and not rape me?

livewirevoodoo · livewirevoodoo's Garage

wow, Im6y... thanks for the post. Definitely one to bookmark for future reference. A great into to a/c systems, retrofitting, etc...

lm6y · 06-10-2005, 03:44 AM

Eldorado, I must have misread your post. I don't know anyone there so I can't help you out, sorry.

livewirevoodoo, That's what this forum is about. I've learned a lot here too!

Lawrence Coppari · 06-10-2005, 04:50 AM

"I'm not a fan of some other refrigerants. Some have butane, or LP gas in them. It seems like if you compress flamable gasses, you have a bomb waiting for a place to happen (like a front end collision)."

The hydrocarbon refrigerants are so efficient that you only use 1/2 as much as you would ordinarily use with R-12. So you only have a pound in the entire system. Furthermore, the gas is distributed throughout the system. An explosion is a remote possibility. Besides, you have a fuel rail full of gasoline plus the fuel hoses in the engine compartment to add to the volume of gasoline. The fear of an explosion is overrated.

I have used hydrocarbon refrigerants in two cars since 1995. The reason why hydrocarbon refrigerants are more efficient than R-12 and R134 is due to the amount of energy associated with the phase change for liquid/vapor phases (enthalpy change for you thermodynamics fans). It is about 50% greater than it is with R12 or R134.

You have a better chance of being struck by lightening.

lm6y · 06-10-2005, 04:44 PM

(quote) You have a better chance of being struck by lightening. (quote)

That's what NASA engineers thought about pure compressed oxygen in a Command Capsule. They re-thought that after Apollo 1. A flammable substance under pressure, under the right circumstances, can be very dangerous.

(quote)Besides, you have a fuel rail full of gasoline plus the fuel hoses in the engine compartment to add to the volume of gasoline. The fear of an explosion is overrated.(quote)

There are a few 944's around that have caught fire due to a leaking fuel rail. There was one for sale here a week or so back.

I respect your thoughts on the hydrocarbon refrigerants Lawrence. And I know you have had good results with them. But with all due respect ( and I do have a lot of respect for you, so we will have to agree to disagree, and hopefully not get into a pissing match), I will not recomend them, or use them in any vehicle I work on. Others are free to make the decision for themselves, on their own cars. I think we have shown both sides of the argument fairly. On the flip side, a 30lb tank of refrigerant (non hydrocarbon) has the potential explosion rating of a few sticks of dynamite, due to it's expansion rate, and very low boiling point.

Refrigerant of ANY type is dangerous by nature, and should be handled with respect.

Lawrence Coppari · 06-15-2005, 07:32 AM

Hey Im6y, did you lose a relative on the Hindenburg? The danger is much less than you think. Besides, there is only one pound in it and it is distributed over probably 80 feet of tubing. Look at your condenser. It is not constructed like a radiator. The flow is all in series, not parallel as in a radiator. Therefore, there is no large volume of gas anywhere in the system. My condenser has about 20 passes, each being over two feet long. I suspect the evaporator is somewhat similar. Then there is all the piping in the system. The gas is distributed over all this volume.

It cannot blow up with no oxygen in the system. Any gas release due to a wreck would be a relatively slow release of the vapor. That could ignite but R12 also burns with one of its products of combustion being phosgene. Incidently, phosgene is what was used as poison gas in WW1.

A UK study has predicted the odds of an ignited passenger compartment leak to be 3 in about 10 million. Any leakage is immediatly noted by the mercaptan odor. Mercaptan is the stenching agent put in natural gas and propane so the slightest leakage is easily detected.

lm6y · 06-15-2005, 03:57 PM

Lawrence, What are your high side pressure readings? I haven't used any type of hydrocarbon refrigerant, so I have no idea what pressures they run at.

I have personally witnessed a MINOR front end collision, and have seen the "cloud" of refrigerant that was released almost instantaneously when there was a collision caused rupture of the condensor. With most refrigerants running around 190 to 275 psi on the high side, there won't be a gradual release of pressure.

There will be a concentration of gas on the high side. It is compressed. From the compressor outlet to the expansion valve is where the bulk of the refrigerant lies. There "should" be a small amount of liquid refrigerant in the beginning stage of the condensor due to the pressure, and the temperature.

If there were no compression, then the pressures would be equal, and there would be no cooling. That's the only time the gas is distributed equally in the system.

I'm not sure what the Hindenberg reference is about, but it does prove that even if the risk is slight, it can happen.

What refrigerant is it you use? I would like to do some more research on it. I remember you said it was cheap ( anything is cheap compared to R-12 these days!), and you had good results with it, but I can't remember the name of it.

AaronM · 06-15-2005, 04:08 PM

Quote:

Originally posted by lm6y
A flammable substance under pressure, under the right circumstances, can be very dangerous. [/B]

Yeah. Because there's no gasoline under compression in the front end of the car to worry about. *rolls eyes*

At the most the LP refrigerants will make a tiny little ball of flame that lives for about 3 seconds.

Gasoline will burn just a wee bit longer.

Being worried about an LP refrigerant when there's that much gasoline is like singlehandedly moving a grand piano up three flights of stairs, and then refusing to move the bench because you're afraid of hurting your back. The term that comes to mind regarding your worries is "ass-backwards".

Aaron

Eldorado · 06-15-2005, 05:04 PM

gasoline is a liquid, and not under the high pressures that the coolant is at.... and therefore would only burn and not explode.

also, gasoline is not as volitile as, say, compressed propane.

you can get a bucket of gasoline and throw a match into it, and the match wont even be enough to light the bucket aflame...

AaronM · 06-15-2005, 05:16 PM

Quote:

Originally posted by Eldorado
gasoline is a liquid, and not under the high pressures that the coolant is at.... and therefore would only burn and not explode.

also, gasoline is not as volitile as, say, compressed propane.

you can get a bucket of gasoline and throw a match into it, and the match wont even be enough to light the bucket aflame...

Assuming you somehow get gasoline with no vapours, yes. However, unless you have a gigantic movie studio wind machine following your car at all times to disperse the gasoline vapours in the case of an accident, they'll be there and they'll ignite.

The point is this: Even if the propane ignites (unlikely given its tendency to disperse in air to the point of being at a non-flammable concentration) it will ignite in a 1 to 3 second "flash" with no persistant flame. Gasoline will leak and the vapours, being, unlike propane, heavier than air, will remain at the scene and not disperse, making extremely flammable concentrations of fuel/air mixture around the car. When those ignite, they will burn continuously because the increased heat from burning the vapours causes more of the liquid to evaporate, generating more vapours, etc.

The flash from the propane will do, at most, enough to singe your eyebrows and leave no burns. The gasoline fire can cremate you. You tell me, which is the larger concern?

Aaron

pokey · 06-15-2005, 06:07 PM

Propane IS heavier than air, as well. CNG is lighter, though.

89AZ944 · 06-15-2005, 06:59 PM

What about some of the R-12 subsitutes?
FreeZone
http://www.heco.net/Whatis.htm

AutoFrost
http://www.bloomington.in.us/~atc/autofrost.html

Anyone have luck with those?

Eldorado · 06-15-2005, 07:21 PM

an "R-12 Substitute" is generally what we're talking about here - a hydrocarbon pressurized gas... they work, but depending on who you talk to (going by this thread apparently) there are safety issues..

and I agree with you as far as the propane example goes... ever left the lid on a BBQ too long with the gas running before lighting it? big ball of fire, no real damage... but a story to last a lifetime.