R12 Replacement

To do a good switchout.. Replace all hoses, the r12 hoses will not hold 134a, 134a is smaller molecule and will leak out of original hoses or hoses older that 20 yrs, very important change out the condenser, the replacement condensers have more piping and fins to cool down 134a which 134a requires. Finally go with the Sanden compressor, most of the old original compressors are just wore out.. no new have been manufactured since 1979 so they all have lots of miles on them. Mine throws cold air like original now.

I was putting aftermarket A/C units into cars back in the 60s, and was Card Carrying HVAC serviceman for a couple of years in the 70s.

I now only do A/C service on my own home and cars, and help out a friend ever once in a while.

Every used 2000+ Ford I have had has suffered "THE Black Death" where the compressor fails and the system is full of black oil.

These all take a new compressor, and new condenser, unlike the old ones were they were serpentine tubing the new ones are more like radiators, so you cannot flush them and get them clean, and new receiver dryer, orifice tube, and a dual system get a replacement expansion valve on the rear evaporator, and a full flush of all lines and evaporators, I have done four of these.

My Van was/is a 93, right at the change over point, so I have run R12 in it. Here is a point: R12 runs with less head/high pressure, and is a better coolant.

The newer propane refrigerants are being endorsed in Europe for their even lower head pressures and thus lower cost to run (pumping loads) and they can do the same in a car, lower pressure can mean a little more MPG and less strain on the overall system. Also oddly the comportments of propane is larger than the Refrigerants, and thus are less likely to leak out.

I my 60 years of driving and servicing A/C units both home and car I have NEVER seen a evaporator LEAK.

Just about the only leaks happen at the compressor's shaft seal, and they need a slight leak to lube that seal so a little lost of refrigerant is a need by product of these systems.

At this time my 02 Ford explorer is running a Propane gas, and it is the coldest system when compared to a 03 Explorer with 134A and a 03 Crown Vic with 134a.

Only my 93 Van when last running match or beat it with R12 and in a dual system.

There is a slight problem with these new gases, NEVER use a standard recovery system that use s self contained vacuum pump, ones that had a electric motor inside the case, like a refrigerators, they can ONLY be pumped out with a true BELT Driven vacuum pump, recovery by a belt driven pump.

And they are consider environment save so venting them into the air is AOK.

I cannot prove rather this gas with its own oil will prevent "The Black Death" as claimed, but considering the cost of a complete rebuild, out of my own pocket, around $600.00, or at a shop $2 to 3K, I am working to convert my other systems to it.

As for a under the hood fire risk, many of us drive fuel injected cars and trucks with injector pressures of 30PSI up to a couple of hundreds of PSI for direct inject systems, a TINY little leak can fill an engine compartment with very explosive gas fumes in seconds...yet we drive these everyday.

I consider that a greater risk that a few OZ of propane.

My 2 cents worth

Rich

If I want to step back up to R135:

It was and may still be suggested to replace all the old “O” rings with new green r134 o rings.

Then Flush the entire system, then install new orifice, drier/accumulator, and add 8oz PAG oil, suck it down to -29" for at least 1 hour (overnight is better) and shut off the vacuum pump and see if it holds vacuum. If it does, then add the appropriate amount of 134A. If you don't eliminate the Ester oil, you'll fight it the rest of your life.

Note if you have a case of Black Death black oils then replace the compressor, condenser as well.

My 93 will charge with 68oz of R134a, and 11oz of PAG 150. That is 4.25 lb of R134a (that is 85% of old R12 charge)

So I need 15% over the R134 more to be at 100% so that is 78 OZ of R12, or 78.2\12OZ cans = 6.51 or 7 cans.

This should be valid even for a van that has had the rear AC added on after leaving the factory. The van conversion place isn't going to reinvent the wheel, it will use stock parts to add on rear unit if they have any sense at all.

If you believe that the rear AC conversion is something different, you should contact them and find out what the coolant capacity is, and how much oil you have to add.

Even with this large of a system more than 1 can over the capacity of the stock system is likely to cause liquid to be deposited onto the low side of the compressor.

If you heard the compressor struggling since the shop installed it, it is likely that they put too much oil into the compressor before putting in the R134a. You would need to drain the compressor of all oil, then all oil out of the system and flush out all lines - then you could install the compressor with no more than 3oz of oil in it, 5oz of oil in the main accumulator, and an additional 3oz in the rear accumulator.

At this point you have probably slugged the compressor, so you will probably have to replace it. You should also replace the pressure sensors while you are at it. You have WAY TOO MUCH R134a in your system, enough so that there is liquid passing through the compressor. You have liquid on both the low and high side, which is a bad thing.

You can't keep adding R134 until the system low side pressure gets to where you want it.

IT DOESN'T WORK LIKE THAT.

If you put too much R134a into the system, the low side pressure will start to drop - instead of what people think will happen, which is that they assume it will keep going up. This is a result of the pressure switches kicking out the compressor, the compressor shuts off before low side pressure can build to 50 psi.

If you have less than the recommended R134a in the system, the low side pressure will be too low.

If you have the right amount of R134a in the system, the low side pressure will be roughly 50 psi or so.

I work with the temps, 35/40 Degrees low side and 50 Degrees above the air temp I am working in, RPMS around 2000.

Note most good gauge sets show THE TEMP as well, I look for a 40 degree split, 40degrees over the outside air temp and 40 degrees on the low side, lower like 32 or lower can freeze any water at the valve and shut down the system.

If you put too much R134a into the system, the pressure will start to drop again from the correct 50psi it should be.

You then need to open up as much of the system as possible to evacuate ALL the coolant from the system, or have the system pumped down by the local shop. You have to clear out all lines with AC solvent to insure that you have gotten all the oil out of the system. You have to clean the entire system out - so that you know exactly how much refrigerant and how much oil is in the system.

If you believe there is a restriction to the rear AC, then you should check the lines going to the rear for an obstruction. It may require removing the lines and replacing them to insure that any restriction has been taken care of.

Rich

With a factory R12 systems, either pay the premium for actual R12 or just do a 134a retro fit. There are some factory R4 compressors from the the mid ‘90s that used 134a from the beginning, so it’s very much possible. Just ensure that all the O rings are replaced with the correct style, the system is flushed, new orfice tube, pressure switch is adjusted or replaced with a new style one, and that PAG oil is used instead of linseed oil. Also try to measure your charge carefully. 134a operates at much different pressures than R12 ever did, so it’s easy to overcharge, if you are not careful.

As for someone who says they've never seen evap leak,they don't happen. I've never known anyone that had AIDs does that mean it doesn't exist.
Lots of other people have seen them,including me, Google it,see how many shops,people,etc are talking about evap leaks. I can't remember if we got two of them in seems we did. Anyways the one I remember is 2001 dodge town and country. Evap leaks do happen. And the point about cars and their gas tanks in the garage,true never thought about that,but IMHO fuel system leaks are nowhere near as common as A/C leaks.

All I can say is what I have seen in some 60 years of driving A/C cars and some 28 old used cars as i never bought a new one, so I owned older cars and drove them in Phoenix AZ were we use the A/C about 6 months each year. NOT one ever had a leaking evaporator, leaking condensers yes and most often from someone working on the car. And my friends who also work on cars one nearly his whole life never once said "Guess what I need to take a dash out to replace the A/C coil," heater cores all the time.

You are right,this never happens.

OH I see those, and of course they seem to mainly start with newer cars, newer that my 03s.

And nothing will surprise me with the newer computer engineered to fail cars, I just said I have never seen a leak, nor heard of a leak in any of my cars and any of all my friends, who's newest car is a 2015 Toyota.

OH BOY have I hears ton of horror stories about newer cars, and worst bad replacement parts...I fear that I cannot get good new parts so I am trying to have a spare copy of a good running mate to what I am driving...so I have a privet stock of good used parts to repair my cars.

I rather run a old god used part that a new crappy new part.

As my junk yard friend used to say when asked "What a USED PART?" he would say "So how new is the rest of your car?"

Even my 03 Ford Explorers (a 02 and a 03) have parts 100% doomed to fail, like HVAC Doors with FLEX hinges, I mean where plastic is bented back and forth every time you turn on the A/C or heat, doomed to fail some day and yes both did have these failures, and the glove department, and the center console has flex hinges....so sooner or later they too will fail.

And every Japanese car (3 so far) we have had has lots of failing rubber (CV joints boots) plastic radiator tanks, zip tubes (tube between the air filter box to the throttle body) just fell apart, even a plastic thermostat HOUSING just broke...wiring problems from bad wire coverings, seems the Japanese figured to make plastic with a 15 to 20 year life span...

We have a 68 VW Bug that its similar parts are still good and was up until about 2000 when we were given a 626 by my mother in law.

And of course I have not see any kind of plastic and rubber parts failing and rotting away on my 78, 87 G20s, Both in storage and used as storage and 93 Chevy van and that is in the AZ dry HOT weather...

Most of my cars have been at least 10 old or older, most nowadays come with a fir amount of miles on the, the Toyota has 150K, my 93 135K, my 02 Explorer 135K my 03 Explorer 220K and my 03 Crown Vic 185K. Most have started life with me with 70k on the or more...

I have seen a lot of failures, and yet...

Rich

Got more feedback from a friend who is full time serviceman:

You've never seen an evaporator leak? Boy are you in for a treat with the new 1234yf systems! The pressures on these are close to what the 134a systems are, and the components (except for the service ports) are the same between the two.

However, 1234yf is flammable and it's also corrosive and WILL eat through an evap core given enough time and the lack of proper lubricants. Both 134a systems and 1234yf systems use the same PAG 46 oil (in most cases, some GMs run a heavier viscosity PAG oil like 150), however they do make a PAG 46 for 1234yf systems which somewhat mitigate this risk. You can use the 1234yf PAG in a 134a system if you want, but you can't run straight 134a PAG in a yf system.

MORE of the make sure the cars will not last...and note 1234yf is flammable!!!!

Rich

PS More:

I asked him: “Have you seen a evaporator leak before??”

He said: “ Yes I've replaced two.”

I asked: “In what cars and year of the cars??”

He replied: “2015 Chevrolet Camaro, 2019 Jeep Grand Cherokee, both were 1234yf systems.”

I've seen literally hundreds of evaporators leak. The largest majority of them were the '96-'01-ish Chrysler minivans. There's probably not a single one of those evaporators that survived and didn't ever leak. There were several other vehicles of the time that were problematic as well, but not to the same degree as those minivans.

bucket said:

I've seen literally hundreds of evaporators leak. The largest majority of them were the '96-'01-ish Chrysler minivans. There's probably not a single one of those evaporators that survived and didn't ever leak. There were several other vehicles of the time that were problematic as well, but not to the same degree as those minivans.

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I had an 07 Dodge Ram 3500 that I had to change one twice in, and 98 Dodge Ram 1500 that I had to replace once. I think the only reason I had to the 07 twice was because I made the rookie mistake of reusing a drier. The majority of other leaks I’ve dealt on all other vehicles are almost always a result of either rotten/torn rubber lines or a damaged condenser. I know that the 2014-2018 “K2” GM trucks tend to leak on the drivers side corner of the condenser. I have also seen some 2016 2500 trucks with evaporator core leaks, though these were fleet trucks that spent all day being left idling with the AC on in rather harsh environments.

fast 99 said:

Certainly, changing over to 134 has been done for 20 years at least. There is a lot of information on how to do it successfully. Refrigerant oil is different, seals, drier, orifice tube, replacing hoses and flushing is sometimes needed. Most of the work could be done in the backyard environment then get a shop to recharge it.

Using some unknown refrigerant is questionable at best. If that stuff is indeed flammable, how would you feel as a tech having a system catch fire? As a shop owner it might ruin a refrigerant recycler or contaminate it. 134a is still available in most places.

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I would be afraid of flammable refrigerants. What if it started leaking into the car, and you lit a match? KA BOOM!

J. B.

Well you could be unable to buy any car made after 2023 as all now use the new
1234yf is flammable and it's also corrosive and WILL eat through an evap core given enough time. Progress is killing used cars.

Rich

peats said:

R-12 usually sells for $25 a can of Craigslist. Sometimes it sells even cheaper when the person doesn't know the value. I buy it when it's reasonably priced.

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Yeah, I have been looking on Ebay. I have come to the conclusion I will find out how much it costs to do a conversion and weigh that against buying some cans of R12 to recharge the system AFTER it is leak tested. I am sure it will be cheaper than a conversion, and I KNOW it is cheaper than a new system from someplace like Vintage Air.