AC conversion... R12-R134a

[audiman]

Tonight was judgment night. I didnt know what to do about. Over the winter the R12 gas had leaked partially, and when I came to use the AC this easter weekend, it wasn't very cold. Compressor was cycling very quickly and the air was not very cold.

After a bit of research i decided to convert to the later style gas R134a, this is a non oxone depleting gas and is readily avaliable. As I seem to be forever taking the car apart and having to get an outside company to de-gas/re-gas the car each time i need to work on it.

The only problems I could find listed in AC books is that the gas molecules of R134a are a lot smaller than R12, thus it is prone to leak, through seals and also the walls of the rubber hoses.

The first thing to do is, if the system has gas in it, is to have it removed professionally, the refrigerant is not toxic, but it is highly illegal to vent it off to the atmosphere.

Secondly remove the slam panel and the aux rad (if fitted) the allows greater access to the top of the compressor where the hoses are attatched. You will need some large spanners, 27mm and 32mm.

Then remove the drive belt and the 4x 13mm headed bolts that hold the compressor to the mounting block. The compressor is heavy so be warned.

Next thing is to drain out the old oil that is in the compressor. This is then replaced with an Ester based oil which is compatible with R12 and R134a. This is due to the fact that the original oil wont mix with the newer gas.

Once drained, refill with the correct amount of fresh oil. (cant remember this off hand, but will look it up and post here at a later date). Then refit the compressor in reverse order. You will also need to fit service port adapters that allow the re-charging equipment to to used.

Once this has all been done have the system vacuumed and re-filled using 85% of the original charge.

DONT use the old refrigerant quantity, as this is too much and the system wont perform at its best. I used 850g of R134a and have found this to be about right, judging by the gauges, but 900g would be fine.

[audiman]

I will have to see what it is like in the summer but my initial findings are good. The system seems to be gas tight and it is operating well. Will have to wait and see. Fingers crossed as it was far cheaper than another R12 re-gas.

As I work in a garage the oil was given to me by a supplier and we have loads of the later style gas in stock! Cheers Dad, have a pint on me

[S2central.net]

Now I thought the normal oil found in R134a systems was wholly incompatible with seals from the R12 system. Did you replace the seals or is this oil you used *specifically* designed for upgrading from R12 to R134a ?

Why not go for the R143a solution (thats one four three) which alleges to be eco-friendly and miscible with R12 ? I must dig out the AC books again - its gonna be hot sometime soon and my damn AC still doesn't work cos of a leak that I haven't been arsed to fix.


Paul

[audiman]

From what I remember, the 143a has now also been outlawed due to its small content of R12. The Ester based oil is fine for use with both types of gas. R134a doesnt mix with the old oils and it sits in the system not lubricating it, causing possible compressor failures.

Im not saying that this conversion will last forever, but its cheaper than changing all the seals and rubber hoses. The only drawback is the increased chance of the system leaking.

I have spoken to several AC experts about doing this and also read books published in the US, where R12 has been banned for many years. They all say that this is one of better ways to convert the car.

If it causes problems with anyones car then im not to blame. Do this at your own risk.

I am prepared to give it a go.

[s2driveruk]

Tom,

What kind of cost are we looking at to make the switch? Mines running R12 still and I need to get the gas removed then update it with the same kind of fluid and gas.

Cheers,

David

[audiman]

Parts wise you are looking at about £15-20 plus the gas which retails at about £10 per kilo.

For the recovery and re-charge expect to pay about £80 ish varies alot around the country.

HTH

[APNess]

Good luck with that Tom. I had mine recharged a few months back and it was as ***** then as it is now, so I must have a leak somewhere too. I just dangle out of the windows and sunroof when the sun shines, and sweat my fat *** off.

Works for me, though wearing shorts then peeling your legs off the leather ain't so nice.

PJ

[audiman]

I have the advantage of if it does have a slight leak, then i just put more gas in, for FREE!! LOL

Plus i did all the work myself and this saves loads of money

[s2driveruk]

Cheers Tom...... I think i'll do that next after sorting my brakes out

David

[audiman]

Just an update..... I found that with only 85% of original charge it wasnt cooling enough on hot days. So I added some more gas until the discharge pipe was condensating. I placed about another 150g in the system taking it to 1000g around thatof the original charge.

I know what i said in the posts above about the charge level, but after reading some more information, in this country, where the humidity and temperatures are not as hot as the US, you need more gas.

System doesnt appear to be leaking loads and it works a treat.

[s2driveruk]

Tom, What oil is required for refilling the compressor do you have a part number/product name as I have found a local garage to de-gas the system for a £10.

Also how heavy is the compressor approx so i can brace myself when if comes off the car

Cheers,

David

[audiman]

Its only about 5kg or so, but it is heavier than it looks! The oil is called Ester oil, you will want about 0.5 litre of the stuff, about 290ml go into the compressor, then on gassing you may need to add a few ml. It comes in different grades. Just get the medium viscosity one.

[porkkis]

R134a is not that environment friendly as generally thought. It does harm the atmosphere. R134a will be replaced with CO2 in the future. Yes, that's correct, carbon dioxide.

R413a (and that is four one three) aka Isceon 49 is proper replacement for R12 and 900g is good amount.

[audiman]

413a is being outlawed too over here too It has a percentage of R12 in it Its a shame as it works really well.

[Stick Insect]

[QUOTE=porkkis]R134a will be replaced with CO2 in the future. Yes, that's correct, carbon dioxide.

QUOTE]

Will our systems manage CO2?. I think not. My system is working fine after it was charged in 1993. I have not run it for a year sometimes! Heaven knows why it's still working! It could possibly do with a top up. It never seems very cold, even back in 1993.

David