exactmetal

R12 is not "dead." It is readily available with a 609 cert. which is very easy to get. $30 a pound is a bargain when you consider all the other expenses either immediately or within a few years of most conversions.

i agree,,,,,,,,r-12 is avail. and really 134a should not be sold over the counter to any body without an e.p.a card.....this is why most a/c systems fail,,,lack of know how and most of all the so called leak sealer instant orfice colgger.......r134a conversion will eventualy lead to comp. failure...

pmihaltian

So what about the A/C specs for the 86, 87 & 88 models? Does anyone have the definitive & correct specifications?

MBDiagMan

My 88 Factory Service Manual and most charts on the internet show 44 ounces, for an 88 of course. I was about to proceed based on that info a few weeks ago before SunCR saved my A$$. He pointed out that it was only 2.25 pounds(36 ounces.) He said to look for a sticker on the evaporator. He might have said the evaporator blower motor. Anyway I looked for the sticker on the evap box and never found it. It's a good thing it wasn't a snake because it was right there on the blower motor when I was looking around this morning.

I am confident that all 88's take 36 ounces, and I fully expect that 87's and 86's do too. Look for the sticker. If it isn't there proceed with 36 ounces of R12 or if you are converting, 26 ounces of 134 worked perfect in mine. That does not mean that I promote changing to 134. I changed mine in the late nineties and I've just never bit the bullet and changed back.

Good luck,
Doc

jhammons01

In advance, I apologize......

See what I said??? Most do not like what I state.

I especially like the tact of someone telling others not to convert over cause it wrecks his machine....that one is rich....

For the Guru's here what is it about 134a that might lead to early failures in systems???

I should wait to see if there are any single answers...but for the sake of expediency....

R12 Has Fluorocarbons..(dichlorodifluoromethane and in few years the HCFC R22 chlorodifluoromethane)......Highly corrosive stuff to the Ozone and other materials it comes in contact with.

If it is contained in an closed loop system with JUST ITSELF the molecule is very stable....however allowed to become a "free" molecule (as in purged into the atmosphere) or if the molecule is allowed inside a system refilled with 134a...then it becomes corrosive to anything it touches.

The "Fomblin" or PFPE oils used (laymen use mineral oil as a term) will be completely contaminated with the Fluorocarbons from the R12. There is no real way to completely scrub that R12 from the PFPE.

So now we have a system that has R12 (nasty stuff) permeating through a refilled 134a system and guess what???

It leaks after a while.

The only way to get "the nasty stuff" out is to take apart the system and clean it out.

And as I said before, How much are you going to dump into a $4000 car??

The experts weighed in with correct information.....absolutely correct albeit with lack of understanding why or what is occuring.

The guy in OC that's been to Corvette Mikes is a prime example. His system has a leak...they fill it with R12, charge him and off he goes....until next week when the gas has leaked out and into the atmosphere. abildgren, your system is not over filled rather it leaks down and the pressure sensor kills the power to the compressor. Your situation is unfortunate as there is no cheap fix. You have to find the leak.

For anyone else, at this point, I still say if you have a slow leak...go away from the R12...there is a reason we outlawing it and moving to much safer gasses. and bottom line...it is just a gas of one sort or another. You compress it and gets hotter....run it through a heat exchanger to cool it back down to ambient...then allow it to expand and a strategic location...say where a fan is blowing and WALA!! it gets really cold....

that is all there is too it...no voodoo magic

Stick a gas in there and let it cool away.

I'll finish with.....if the system was in good shape to begin with...why would anyone consider converting it??

I'll tell you why......cause it wasn't in "good shape"....the system already developed a leak....it was broken to begin with...else you'd be leaving it alone and riding in cool temps....

...So blaming 134a for systems "failing" is flawed to begin with. Who takes a perfectly good working system and just out the blue decides to convert it over???

No one.

mako41

If you have a leak, Fix It!!!!!!!

Don't convert to R134a because you have a leak!

Fix your leak, and recharge with R12.

It's the refrigerant your A/C system was designed for, from the factory!

It works better, and is more efficient than R134A to cool your vette!

It will be much less expensive and much less of a hassle to use than converting to R134A!!!!!!!!!

End of story!

MBDiagMan

BC632,

I'm just curious. How many of your converted systems did you see and follow up on, three or more years later. Did you have a lot of repeat business?

Just curious,
Doc

MBDiagMan

I don't know who you are directing your comments toward, but I will respond.

R134a conversion, in and of itself does not necessarily cause problems "down the road." Poor conversion practices, causes problems. I have seen plenty of improperly converted systems have shortened compressor life as well as rotted condensors and evaporators. I will let YOU, determine what is and is not a correctly converted system.

Mixed oils can easily lead to less than optimum compressor lubrication. Many conversions end up with inadequate oil. Improper evacuation allowing moisture to combine with the refrigerant creating an acid is a worse problem with R134a than with R12.

I have done a number of conversions, some of which were done thoroughly (flush lines and compressor, replace o-rings and r/d, correct amount of Ester or PAG and a THOROUGH evacuation) that still seemed to have more trouble than properly repaired R12 systems kept on R12.

I do NOT recommend conversion because of a leaky system, that would result in leaking a less expensive and so called less dangerous refrigerant. I strongly recommend that in a leaking R12 system, that you CORRECT your leaks, do your best to have the correct amount of oil and recharge with R12. I emphasize FIXING THE LEAKS!

As far as R12 being harmful, I handle it as if it were. I reclaim, recycle and am very dilligent in finding leaks, and I NEVER knowingly release ANY refrigerant. I'm very dilligent in taking care of reclaimed refrigerant and preventing it's contamination. That said, I still don't buy into the Chicken Little, Sky is Falling thinking about R12.

Doc

SunCr

I agree with you Doc and everything you've posted. Unfortunately, a 4000 Buck Vette probably isn't going to get what it takes to make it right as it will cost 1/3 to 1/2 as much to put it there - and it'll still be a $4000 car. Hopefully, you can at least keep it safe; ie, don't mix gases or gas with air as that can trip the high pressure limit. If it's broken (or worse yet, jumpered), something can blow up. And staying away from the flamables should be obvious, but the Laws governing that stuff all go to the end user, so they're easy to come by and people buy into the hype.

MikeC4

Fleet cars !!!! We don't drive no stinkin' Fleet cars here !! I can just imagine what upper management said to the AC technicians: "OK fella's, let's get this done as quickly and cheaply as possible, just empty the old stuff out and dump in the new stuff. It's a govt. mandate and this is going to cost money" ........

Bad advice to put on a CORVETTE Forum. No doubt, the above method would work temporarily, but for how long ? I am sure that those Fleet cars are sold every couple of years or so, and I feel sorry for the consumer who ends up buying one of these...

Note to self : Never buy a used Fleet car

jhammons01

And you'll get no argument from me on everything stated as being true. (only exception I'll take is with the Fluorine Molecule being the basis of R12....very very nasty stuff)

That being said who is going to do this to a car that is probably within a few years of being towed to the reclamation center itself?

Your advice is for the man that has his car listed with the Corvette Registry.......My advice is for the guy that has a broken A/C and would like to patch it up well enough to last for the next three years. Should my client fall upon the winning Lotto ticket, He'll no doubt bring his 100K mile C4 to you for a complete overhaul of the A/C system, or trade it in on a Z06...whichever comes first....

As I said before, YOU are right.

No really, I am being serious, you are correct in what you state.

If I had a shop and I were a businessman with a reputation to maintain, I wouldn't say anything that I say in this thread. That being out there.......Where is the alternative to what can be done for the poor guy sitting in summer heat, bumper to bumper traffic with his windows open and a glowing catalytic converter directly under his seat heating the entire cabin???

$50 bux and 30 minutes has that guy sitting in luxurious cold temps the very next day......

Just for kicks....the Celica I had two cars ago.....it would shoot small ice crystals out of the center vents on 95° days....My friends would get a kick out of it.

Rocket22

I had a very small leak in 1992 ford mustang convert. and figured I would try the $20 repair on this summer only pos. The system was professionally evacuated and one of the $20 conversion kits with stop leak was added and 60K miles later it was working fine. Same with my parents 1990 caddy.

The cost of repalcement was not an option as each car was north of the 150K mark so it was worth the quick fix attempt. In the worst case I was going to end up with no a/c which is what I had anyway and had suprisingly good results.

On that note one of the reasons I bought a 1994 is I wanted the 134a system (and the second airbag).

onedef92

The original poster is seeking to repair his a/c in a proper and responsible way. IMHO, the BEST way is to find the leak, repair it, make sure the drier is okay and the correct amount of mineral oil is in the system and then charge with R12.

Amen! That's what I did when I decided to convert BACK to R12.

SunCr

All of this must be why the EPA's current study/proposal includes outlawing all DIY a/c work. For the curious, more is here:
http://www.epa.gov/cppd/mac/service/
Make sure your representative or SEMA is aware of your objections.

BBC632

This is a reply about R134 conversions and "Fleet" cars. R12 was deemed harmful to the environment years ago and it's use was prohibited. EPA rules outlawed the sale of R12, the City of Los Angeles was NOT about to continue it's use. That being said, in operation all AC systems are the same, the function of a refrigerant, R12, R22, R134A is to remove heat, plain and simple. We also recycled R12 and reused it. If you can afford the $5000.00 recycle unit and plan to use it a lot?? that's fine.

But, R12 has it's place, it will work, but is harmful. R134A is the replacement now, it functions the same as R12, very similar properties. "Fleet" vehicles include all City vehicles, Police, Fire, Rec & Parks, Heavy Duty Construction- Cat, GMC, Mack, Peterbilt, you name it, if the City had it, we fixed it. Also City Government vehicles, Councilmen, Mayor, staff, etc.

Of course they didn't drive Corvette's at the taxpayers dime. But to say a "fleet" vehicle is somehow different and my experience is not worth anything? is the reason Corvette owners have a bad rep. Just because someone choose to own a Vette doesn't make them any better than the next guy. It's just a car, much like many others.

The window of time we did R134A conversions was small, most fleet vehicles are replaced every 10-12 years (7) is the alloted time, but that didn't happen. Plus to think working on a $167K Peterbilt or GMC General is below you, think again.

The fact that a person wants to know more about any subject, whatever it may be, is reason enough to give advice, if you have any. Some may not agree, but most vehicle systems work very much the same, AC being one of them. If you don't understand the principals of heat exchange and the use of refrigerant?? You should read up on it.

Brain tease for Vette members... EV1 & Electric S-10 use diesel fuel, any idea why? Also, how do you heat the pass compartment of a electric vehicle?

I have over 35 yrs of experience working on Cars & Trucks & Equipment, all types. I worked with Frank Pisano, Pisano Bros Funny car team, SCTA President Don Carr and his Blown Alcohol Hemi Lakester, Don Carr & Barry Kaplan, you can look them up.

The R134A conversions can cause problems, but my own personal car has been running it for 10 years and no problems. I have all the tools to convert a car or truck, so it's easy for me, I can read the gauges & outlet temps and know what's happening. If your high dollar Corvette is having a problem, just remember, it's just a car. The City had lawn mowers that costs more.

I am building a 638" BBC now, Dart tall block, 4.625 bore, 4.75 stroke, Dart Pro 1 355 CNC heads, may use a Procharger or go NA. Can go to 1200-1400HP easy. Experience helps. I didn't work at the City for fun, it paid very well, but Hot Rods are my passion.

MBDiagMan

BC,

In many cars the conversion to 134 is indeed feasible IF that particular system has enough reserve capacity. Most Vettes do NOT have such reserve capacity. That's what makes them different. It has nothing to do with the attitude of the average Vette driver.

I'm sure that a refrigeration expert like you understands that the capacity of the system is largely determined by the size and capacity of the condensor. There is no room to add a larger condensor in most Vettes and I expect that there are some models for which a PF is not available.

As for your belief that R12 will melt the Polar Cap, it is your right to believe that this is fact. It is also the right of others to believe as they choose.

Doc

SunCr

Why not leave the science to the Engineers who design mobile systems? They understand things like the Perfect Gas Equation/Enthalpy/Dalton's Law (well maybe a DIYer should know this one because the old guy figured out that the total pressure of combined gases equals the sum of the individual gas pressures with each gas acting as if it occupies it's own space - don't combine gases!).

The DIY'er should know a few things: 1. The compressor does the work; first by increasing the vibration of the gas molecules which increases their temperature and then pushing it into the Condensor. 2. At the Condensor, air flow causes the gas to give up it's heat and as the molecules slow down, it condenses becoming a liquid (heat transfer). The compressor continues to push that liquid into and through a metering device (dropping it's pressure) and onto the Evaporator. 3. In the Evaporator, the liquid boils returning to a gas. The energy for that boiling is provided by the surrounding air so it gives up it's heat and you get cold air (heat absorption) 4. The suction side of the compressor brings it back and it all starts over, though along the way, it flows through an Accumulator which dries any moisture in the gas (that's generally left from the Factory due to the 10 minute and pump/dump it got on the Line ) BUT it also traps any liquid that didn't boil - like the process in you engine, it's going to quit if it trys to squeeze a fluid.

The most important things to know: 1. Common refrigerants R12 and R134 at a pressure of 30/28 psi have a saturation temperature of 32 degrees. This is your low side goal - achieve this at anywhere from 70 to 80 degrees and it should at least pump 60 degrees out of the vents when it's in the desert (100 plus - a nice 40 degree delta) 2. R12/R134 are really cold at normal atmospheres (that's the pressure of the air around you) -22/-15 degrees - wear gloves/protect your eyes when working on any mobile a/c system! As I said earlier - keeping it safe matters as much (if not more) as cold air.

MikeC4

You missed my point entirely. A PROPER R134a conversion requires a complete FLUSH of the the system to remove the mineral oil and and any debris. R134a and mineral oil have compatability issues, so leaving the old R12 oil in the system is NOT recommended. The mineral oil left behind will not mix with the R134a refrigerant. That is why you need to replace with correct PAG Oil. The PAG oil will mix with R134a and lubricate the system components. The mineral oil just finds a low place in the system, where it stays, until it is removed at some later date during future maintenance or repair. The mineral oil does no good, but it does no harm. The "O" rings should be replaced with either NBR or HNBR replacements, as these are made of denser material and will create a tighter seal to help better contain the R134, which has a smaller molecular size than R12. Also, it is always a recommended to replace the accumulators/receiver dryers in a R134 conversion.

I wasn't questioning your competence as an AC tech, just the half azzed methodology your shop used on conversion of the FLEET vehicles !! It's obvious that the method you described was done in a manner to incur the least cost per vehicle. That's just politics.

MBDiagMan

BBC,

The REASON that I point out the limited size of the Vette condensor is that a 134 system requires roughly 20% additional condensor size to provide the same cooling performance as the same system charged with R12.

The vast majority of cars have enough reserve capacity, meaning a little extra condensor size such that conversion to 134 is still within the capabilities of the system. Some cars, many Vettes being among them as well as many German cars of the 70's and 80's, BARELY have a large enough condensor to function with R12. Changing them to 134 puts them on the edge.

In a mild climate such as LA, even these cars may very well have adequate performance after 134 conversion. On an August day in Texas, however, it is often a different story.

Doc

fxr4

I worked in a shop years ago and they had an old refridge compressor that we used to pull down a/c systems, and it worked good. It would pull vacuum down to -29 lbs on the low side, but I don't have access to it anymore. So when I replaced the compressor and dryer on my 86 the other day, I thought, wait a minute, I've got a "vacuum pump" right here on the car. Bypassed the switch to get the compressor going, opened the high side only, and let it pull itself down. It easily pulled almost -30 lbs vacuum. Let it run for about 20 minutes, closed the high side valve and let it set to check for leaks. Works great. While it may not be textbook, it seems to be a great way to evac the system using its own pump...the compressor.

desertmike1

Wow.....