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John Beech
Prolific User
Username: jbeech

Post Number: 110
Registered: 10-2016
Posted on Tuesday, 06 December, 2016 - 06:58:   Edit PostDelete PostView Post/Check IP

In another thread, Omar (who lives in Dubai) wrote in part . . . "Our climate is hot and humid. I rarely drive the car in the summer as the heat is too much for both the car and me. The airconditioning cannot cope with ambient temperatures above 48 degrees, so I just park the cars up in the summer.

48C = ~119F and I certainly don't blame Omar for opting out of using the cars when temps reach those levels! Here in Central Florida we only rarely see +100F (38C) but humidity of 90% is common - like it is for Omar (and FWIW, I assumed Dubai was a desert climate until I looked it up on Google a little while ago). Meanwhile, my only exposure to very high ambient temperatures has been in the desert southwest of the United States (areas like Phoenix, AZ and Moab, UT) where 45C isn't outside the norm for summertime. There, however, the humidity is significantly reduced (like 20%) and when you open the car door the blast of heat feels like opening an oven. That's a totally different experience versus Florida's climate - and Dubai must be very intense because you have Phoenix-heat combined with Florida-humidity!

Anyway, older cars like Tootsie (SRX6816) have an A/C system based on R12 refrigerant. Back in 1992, the EPA ruled against the continued use of R12 and forced an industry-wide switch to R134a. However, while there are R12->R134a conversion kits, my understanding is the result are a significantly less efficient system with loses of about 30% of the cooling capacity - yikes!

Anyway, Tootsie's system is still cooling, but just barely, and thus, I am going to top up the Freon soon. I have been able to purchase two one-pound cans ($25 each and I remember when cans of Freon cost $3). Meanwhile, I have found a 30# (pound) bottle with a purported 12# remaining for USD$100. Since the going rate for 30# bottles is US$D$300, the 100 bucks seems fair. and I'm going to buy it. By the way, he's a private seller because otherwise I'd need to take the EPA609 exam (open book). The test costing $20 so it's more of a nuisance than anything. Of course, even 12# is FAR in excess of my needs but means saving my 1# cans for 'just in case'. Interestingly, I was chatting with an retired A/C mechanic the other day and he made a comment that caught my attention. Seems he tops up his 1959 Cadillac A/C system with propane - yes, propane! And FWIW, flammable coolant-replacements are illegal but apparently work just fine and are even more efficient than R12 (just as a point of conversation instead of intent).

Anyway, what's the group-think on R12 in our old cars? Has anyone switched to R134a and had good results? Am I on the right track sticking to R12 as long as I can find it? I saw where Brian has an equivalent drier part number to what's in Tootsie on the off chance my tech decides to vacuum it down instead of simply adding fluid.

John, who plans to stick to R12 but is curious what others have done/are doing.
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 742
Registered: 4-2016
Posted on Tuesday, 06 December, 2016 - 07:09:   Edit PostDelete PostView Post/Check IP


My car has been changed to R134a. It works very well, and I cant tell the difference between it and the R12 setup.

Whichever way you go, be sure to do a full service on the A/C system including the compressor & replace the receiver dryer.

Doing a full job is much better.

God knows how old the receiver dryer is in your car, and it is a major part of a good working A/C unit.

Also check all fittings & connections for damp spots. If there is any, replace the seal or O ring, don't just tighten as these will be to old to survive re tensioning.
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1216
Registered: 5-2015
Posted on Tuesday, 06 December, 2016 - 09:57:   Edit PostDelete PostView Post/Check IP

The R12 aircon system was very good in the Shadow so any slight loss of performance with R134a is not noticed.

If possible I would hang on till 2017 because there are some legal stuff in the pipe line concerning a new R gas that Mercedes have been checking out.

After replacing the bits and bobs get the system vacuumed down to 29 mmhg plus and held for 30 minutes to boil away any damp.

Its ok to pressure test with compressed air but the system must be vacuumed after.
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David Gore
Username: david_gore

Post Number: 2342
Registered: 4-2003
Posted on Tuesday, 06 December, 2016 - 20:19:   Edit PostDelete PostView Post/Check IP

Some hard won experience on aircon regassing in recent years from my well-worn Toyota 4WD R12 system:

1. R134A is not a reliable long-term substitute for R12 as the molecule size is much less than that of R12 and the R134A permeates through the flexible hoses and escapes to the atmosphere. I have had 5 gas replacements in as many years and the longest just survived our summer season before the vacuum sensing switch shut down the aircon system due to loss of vacuum from the refrigerant escape. My aircon recharger changed the compressor oil to one containing a UV-responsive dye to reveal any leaks and this failed to reveal any traces of a leak/leaks after the recharge eventually dissipated. We then did a vacuum hold test for 48 hours without any loss of vacuum so the system was gas tight for external Oxygen and Nitrogen molecules leaking into the refrigerant circuit. At this time, I was seriously considering replacing the flexible hoses with R134a compatible items although this was problematic as the hose connectors required to match the originals were no longer available.

2. On my last trip back to the NSW Mid-North coast I happened to see my aircon mechanic who told me he now had supplies of the new refrigerant for R12 systems and had been getting very good feedback on performance and longevity from owners of older R12 vehicles like mine. I immediately arranged for my system to be given a vacuum test and, if no leaks were evident, recharged with the new gas. So far including several days of high humidity [80/90%] and high temperatures 38+deg C, the system cooling has matched its performance with the original R12 refrigerant and significantly exceeds what was achieved with R134A immediately after recharging and before the eventual loss of refrigerant. A pleasant surprise was the cost being 20% less than the cost of regassing with R134A.

Unfortunately, I didn't get the local brand-name for the new refrigerant and this will have to wait till the new Year as I will be in Sydney for most of December and only going back for the Xmas/New Year holiday period.

There is a new refrigerant [R406? - Duracool 12A in USA/Canada] available for R12 systems which is compatible with the R12 hoses thus reducing the possibility of long-term leaks and would only require replacement of the receiver/dryer and possibly the R134A compressor oil, vacuum leak test and filling with the new refrigerant. I think this type of refrigerant is what has been used in my system

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Brian Vogel
Grand Master
Username: guyslp

Post Number: 2146
Registered: 6-2009
Posted on Wednesday, 07 December, 2016 - 01:41:   Edit PostDelete PostView Post/Check IP


Not that I doubt your testimony, but my own experiences and those of a number of others who've done R12 to R134a conversions suggests that yours is by far the exception, not the rule.

SRH33576 is an R12 to R134a conversion and from all appearances is using the original, or at least old, hoses. It's been running cold since I got her in 2006. I have also noticed no change in performance over the course of this season (only converted in July of this year) in my 1989 Cadillac which had been an R12 system.

Heaven knows, though, if there's something better than R134a for a conversion then I'm all for it. I'm just trying to keep AC systems that can be serviced as needed, and that rules out R12 as a viable option (even though I have at least one local shop that can still charge with R12 - that won't last for long).

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David Gore
Username: david_gore

Post Number: 2343
Registered: 4-2003
Posted on Wednesday, 07 December, 2016 - 07:39:   Edit PostDelete PostView Post/Check IP


I can only relate to Australian experience [we almost certainly use our car aircon systems more frequently due to our climate] and comments from my aircon serviceman. He did comment on the number of conversions he had done and the number of charging cylinder replacements he has had to order to keep up with demand [country people keep their cars longer than city people for a variety of reasons especially the large proportion of the older generation who live on Government pensions] once the news of new alternative refrigerant and its performance got around.

It would be interesting to find out if your flexible hoses between the compressor and car body were changed to R134A-compatible hoses with the conversion. As R12 is apparently still available in the USA but on a declining basis, the percentage of US conversions to R134A may have been a lot lower than they have been here especially where extreme heat is not a daily occurrence.

The fact a refrigerant supplier took the time and effort to develop an alternative to R134A suggests to me there was and still is a viable market for R12 system replacement refrigerant from car owners with a similar experience to myself.

I am stuck with my current station wagon style work vehicle with its drop-down tailgate as I need the ability to carry large bulky items such as refrigerators, stoves and washing machines as well as building materials. The alternative new vehicles on the Australian market with this configuration are single/dual cab open tray SUVs which have drop down tail gates but do not have sufficient space and security for the tools I always have to carry for property maintenance even when fitted with an after-market enclosure. The other alternative new vehicle available is the forward-control delivery van which I am very wary of because they are very prone to occupant injury in frontal impact collisions due to the limited crumple zone arising from this design. Unfortunately, the proportion of car/truck collisions here is high due to poor driving standards and pressure on contract truck drivers to drive in an unsafe manner if they are to make a living from their contracts which have very low rates of pay and late-delivery penalties.
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Omar M. Shams
Grand Master
Username: omar

Post Number: 936
Registered: 4-2009
Posted on Thursday, 08 December, 2016 - 03:42:   Edit PostDelete PostView Post/Check IP

Dear All,
pelase note that not all R12s are the same nor are all R134as either. There is crap 134a and great 134a. There is also a mish-mash of virgin and recycled gases. In particular the majority of R12 worldwide is not virgin. It is therefore mostly contaminated and can never be expected to operate at 100% performance.

When R134a was first introduced, the gases we were using (certainly in Dubai) were resulting in loss of performance compared to the previous R12. Not anymore. The quality of the modern 134a gas (if you buy the good stuff) is as good if not better than the R12s.

I have not experienced hose issues with my R134a converted cars.

The secret is - every time you open up the system, fit a new reciever drier (and always in the last 20 minutes of rebuild to minimise exposure to moisture) and then vacuum as hard as you can. If you are able to remove the condenser and flush out any accumulated oil then even better. You will be amazed how much oil ends up there that you cannot eject by simple blowing.

When you introduce gas and oil into the system you need to have the driest cleanest system ever. Then watch the fireworks - the best aircon ever.
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Unregistered guest
Posted From:
Posted on Thursday, 16 November, 2023 - 10:53:   Edit PostDelete PostView Post/Check IP

I know this is a very old thread, but for anyone else stumbling across this...

"Unfortunately, I didn't get the local brand-name for the new refrigerant"

Hychill Minus 30 sounds like what was being used. Many AC techs hate it because it's basically BBQ gas (propane/isobutane mix, but refrigerant grade so fewer/no impurities like regular LPG) and so they have to be a bit more careful with it, but those that regularly work with it say it's great.

There's also been a scare campaign over the past decade or so by VASA and similar organisations paid by Dupont to try to turn people away from cheap, effective refrigerants for the DIYer that don't require forking out cash for a license, but considering that it's been legal in Victoria for at least two decades, and Europe has been using HC refrigerants for a while as well, the fact that we don't hear horror stories on the news is interesting to say the least.

Personally, I regassed my car with the stuff and even though it's underfilled (couldn't fill it properly at the time), it still blows extremely cold. For old R12 systems, the stuff works great, better than an R134a retrofit. The molecules are apparently bigger than even R12, so losses via permeation will be even slower/less than R12.

(Message approved by david_gore)
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David Gore
Username: david_gore

Post Number: 4243
Registered: 04-2003
Posted on Friday, 17 November, 2023 - 09:49:   Edit PostDelete PostView Post/Check IP


The use of LPG as a refrigerant has been around a long period of time however its use in automotive air conditioning has always been frowned upon due to the claimed potential fire/explosion risks in the event of an accident.

Like you, I am aware of cars that have air conditioner conventional refrigerant replaced with LPG with excellent results and it is my opinion the fire/explosion risk in an accident is no greater than with conventional refrigerants and liquid fuel given the small amount of LPG used to charge the A/C system.

I strongly suspect this has been a ploy by refrigerant suppliers to keep this market and the associated profits for themselves. I am firmly of the opinion, the ban on LPG refrigerant is nothing more than a profit-protection measure by the refrigerant suppliers.

The fire/explosion risks of LPG in cars is most likely less than the same risks for conventional petroleum fuels as the amount of refrigerant in the A/C system is substantially less than that of the volatile petrol/gasoline fuels in common use for decades. I recall reading test data several decades ago that confirmed LPG fuel had similar risks to conventional petrol/gasoline and a slightly higher risk than less-volatile diesel fuel in accidents.


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