Aircon - R12 to R134a, worth it?

Justin_Elliott

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Apr 3, 2010
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When summer finally arrived I realised that my aircon has stopped working, so took it down to my local garage for a recharge and it appears its a little more involved... Firstly the system was Empty (a 'full recovery process' retrieved absolutely ziltch) and my system is R12 (its a '93, so about the time systems moved over to R134a).

So they've recommended I consider changing over to R134a as they believe, considering its age, they'd be doing the majority of work required anyway and a refill using a R12 compatible gas costs much more...

They recommend changing over the o-rings, compressor seals, schrader? valves, expansion valves and dryer along with a full flush of all the pipework prior to a nitrogen purge to check the system (including the only parts not 'meddled' with - condenser / evaporator) - so all in all the complete system then! They declined to give me a fixed price to do the whole lot but said it'll be 'considerable' :icon-rolleyes: - although by that point I'd pretty much decided to come away and do some homework/searching...

I agree that replacing all the o-rings in a 20 yr old truck sounds sensible and I was expecting to replace dryer and other 'minor items' but is the full conversion a good idea?

I've read a couple of detailed write ups which cover replacement of major components - and this does look doable - so considering the system is already empty, should I consider completing the majority of any work required myself?? I was thinking, with a little guidance, I could strip down, clean / flush and replace all seals/major parts and get the experts to purge/test prior to adding refrigerant... So what say you all???
 

AndycruiserguyLomas

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Nov 19, 2010
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I too would b e interested in feedback on this one as I intend to have the silver 80 regassed shortly. It hasn't worked for about 6 years but has only done about 4K miles bin that time.

Andy
 
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Steve Wright

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Mar 4, 2010
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When summer finally arrived I realised that my aircon has stopped working, so took it down to my local garage for a recharge and it appears its a little more involved... Firstly the system was Empty (a 'full recovery process' retrieved absolutely ziltch) and my system is R12 (its a '93, so about the time systems moved over to R134a).

So they've recommended I consider changing over to R134a as they believe, considering its age, they'd be doing the majority of work required anyway and a refill using a R12 compatible gas costs much more...

They recommend changing over the o-rings, compressor seals, schrader? valves, expansion valves and dryer along with a full flush of all the pipework prior to a nitrogen purge to check the system (including the only parts not 'meddled' with - condenser / evaporator) - so all in all the complete system then! They declined to give me a fixed price to do the whole lot but said it'll be 'considerable' :icon-rolleyes: - although by that point I'd pretty much decided to come away and do some homework/searching...

I agree that replacing all the o-rings in a 20 yr old truck sounds sensible and I was expecting to replace dryer and other 'minor items' but is the full conversion a good idea?

I've read a couple of detailed write ups which cover replacement of major components - and this does look doable - so considering the system is already empty, should I consider completing the majority of any work required myself?? I was thinking, with a little guidance, I could strip down, clean / flush and replace all seals/major parts and get the experts to purge/test prior to adding refrigerant... So what say you all???
Hi Justin

JUst to let you know, R12 gas is illegal and has been since 31-12-2009
 

Justin_Elliott

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Rob;

Thanks, I've read the post through and I was thinking the same thing... although as I've got a leak I might as well replace the o-rings prior to pressurising checking for the leak? They want iro £45 just to say where it probably is leaking from...
I got the feeling they sub-contract non r134a work out as it carries a much higher surcharge (iirc £100 + a higher recharge fee)...

I guess if I/they replace the o-rings and this fixes the leak it would be the cheaper route, but if I end up replacing major components I'd be better to do the flush/switch over...


Steve - Yep I'm aware of that, although IMO considering as you can still get R12 in many countries, making it illegal in this country (considering our relative size) will make absolutely no difference to the global effort to reducing greenhouse gases! But at least when we're sitting there with mediocre air con (R12 is far superior to R134a) we can feel satisfied that the reduction in global warming rates will make the few degrees difference irrelevant...
 

Towpack

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Rob;





But at least when we're sitting there with mediocre air con (R12 is far superior to R134a) we can feel satisfied that the reduction in global warming rates will make the few degrees difference irrelevant...
In what respect? The AC on my LC (R134) pumps out air at 4 deg C from the vents. I'd hardly call that mediocre.
 

Justin_Elliott

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Don't get me wrong, when a system is designed using R134a it can perform very well, but not as good as R12 could have for the same energy usage... So yes R134a systems do perform 'good enough' but change a system from R12 over to R134a it will be even further down the efficiency curve... It's one of the few facts which I can still recall from hours and hours of thermodynamics lectures - and tbh I had a hangover for most of those.

Edit: Should add - its been a while and I'm far from pretending to be an expert in the field! It didn't take many of those lectures for me to realise I wouldn't be exploring a career in Thermodynamics...
 
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Jon Wildsmith

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I think it's usually the condenser or dyer joints that fail although Frank had a perforated hard pipe along the bulkhead. If you can get some die in there and a UV torch off ebay you should be able to see where it's leaking. Toyota don't sell the o-rings on their own, you only get them when you buy the pipe they go on, so just get some from an aircon place. You may find some joints are corroded and just putting a new o-ring on isn't enough. I would only tackle the ones that show a leak or you are messing with to change other components rather than trying to do them all.
 

frank rabbets

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Mar 1, 2010
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Hi Justin

Take it all apart up to the bulkhead joints. A leak beyond this is unlikely. You will just need new "o" rings to convert from one gas to another. You must replace the drier as once used they have water in them. If the condenser looks old replace it. You've now covered the usual/vulnerable joints but split the others, check and change rings. Check all the pipes for signs of oily staining. The one on the bulkhead corrodes through. By this time you will know if your oil is green or clear. If green there is a dye and you can check, as Jon said, with a £5 UV torch off ebay. If there is no dye you'll have to take it to an aircon garage and ask them to charge it up with the dye in. Then they should check for old and new leaks.

This is a very easy job. Make sure the "o" rings are a definite tight fit and lubricate them with the oil first.

Frank
 

Dave

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Apr 6, 2010
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It's always best to convert to R134a as it's the industry norm - everyone can work with it, it's readily available, and it works.

Trying to take apart all the joints may be a problem as the steel screws and ally fittings are not a good combination. Let sleeping dogs lie is usually a good idea with old cars and old a/c systems. Swap the filter though, and maybe take off the compressor and see if you can drain any of the old oil out. With R134 you will need new oil, preferably an ester oil as this works with everything, and new fittings to convert the old valves to the new style. Whilst it's preferable to remove all the old oil, without taking everything apart it's next to impossible. It will sludge up and park itself somewhere in the system and shouldn't cause too many problems. Most will be in the compressor and drier anyway.

Bare in mind that having replaced the filter and removed some oil, you will still have a leak (or two) somewhere that will become apparent when it gets up to pressure (hence using R134 is it may need some return visits). You may also find that the sudden strain on an old compressor will be too much for it. You also need to make sure the fan is working properly and moving plenty of air.

To get to this stage shouldn't cost a lot of money, and will at least give you an idea of likely problems.

Many of the later R12 systems had R134 compatible components, so performance should be ok, as should existing O rings and hoses.

I gave up converting R12 systems some years back due to existing problem showing themselves after conversion. Despite explaining everything to customers, them paying to do a half decent conversion, and then having to charge them a bunch extra after their initial outlay to fix the faults, it was just a pain. I got tired of being accused of ripping them off, reported to trading standards etc. It was easier to either 'quote a go away price', or refuse the work and let some other chump have the aggro.
 

Geert

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Jan 13, 2013
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I just had my 92 ac converted to R134a.
They recplaced one aluminium tube that is running against the firewall. It is a common place for leaks beacuse the aluminium rubs against the steel...
I had one extra tube (second hand), that also had a leak. That part of the tube is the only part that is undeliverable now at mister T. I wonder why :)
I must say, I've been testing the ac for two weeks now, and ik works great. With a temp gauge in the air vents, the minimum temp was 3.8°c at first. Later on it even dropped to 3.1°c
Pretty cold :)
I went for the conversion because I want a reliable ac that can be repaired in most countries.

DSC_1137.jpg


DSC_1141.jpg
 

yogi

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:thumbup: I'd bet not many people knew about that Damjan.
Sadly that doesn't surprise me at all.

I personally think that any 'environmental improvement' attempts by our governments are either revenue generators, scams to make money for multinationals or placebos.

In the last 10 years or so the Irish government has promoted an EU funded programme called th 'Rural Environmental Protection Scheme' for us farmers. Its worth about 7500 a year to you.

To protect the environment you have to dig out all your drains (further reducing habitat), butcher most of your hedges and put up miles of electric fence. Animals are not allowed to drink out of natural water sources so you also have to lay lots of plastic pipe and put in a water supply. Furthermore youy can't overwinter stock on the land, you have to put them in a shed and generate as much slurry as you can.

Even more amusing is that if all you own is one big field of lets say 100 acres its cheaper to get into the set up than if you own 10 fields of 10 acres with the miles of associated hedgerow, so guess what people do before they join.....
 
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