R12 to R134a conversion.

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DavidRutherford
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R12 to R134a conversion.

Post by DavidRutherford » Thu Feb 23, 2006 2:18 pm

Considering the number of people on here who have done this conversion on a BX, it's well worth asking about....

The TZD's aircon system is of course almost completely devoid of gas. R12 is simply not an option. When I re-did the aircon on my 405, I had the old R12 system filled with R413a, which is a blend of R134a and isobutane, which means you don't have to change all the seals, and it's compatible with the old compressor oil.

But.. R413a isn't well known, and wasn't that cheap either.

To convert "properly" to R134a, my understanding is that all new rubber seals are needed, and the oil in the compressor has to be changed for one that is compatible with R134a. The TX valve will be OK, and a new receiver-drier will make sure the system stays moisture-free.

Am I missing anything... and where have people got their seals etc. from?

I've built new fridge plant in the past, so have no problems with doing the bits needed, just don't want to miss something that's BX-specific.

As an aside.. I also have another compressor (from a 405, hence will fit) which is an R134a one. Is it worth changing the BX R12 one for this one? I'm thinking probably not.
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Post by mat_fenwick » Thu Feb 23, 2006 3:09 pm

I got all my seal from an air con service company (Mitchells in Gloucester), for nothing on the agreement that they would recharge it afterwards.
I think the BX compressor prefers the R12 compatable oil, but can be used with the modern stuff with a shorter life.

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Post by AlanS » Fri Feb 24, 2006 6:54 am

THe black seals have to be replaced by green neoprene ones, the receiver dryer has to be replaced with one with a 134a compatable dessicant (something "9" from memory) I can search it out for you if necessary, oil in the compressor MUST be changed to a PAG oil if not, it's on par with running Dot4 brake fluid in an LHM system, totally incompatable and will cause compressor failure amongst other nasties. This is advice from Sanden who make the compressors fitted to the BX.
T/X will go either way R12 or 134a and don't be surprised if the leak in the system is on the T/X valve as this is a common fault with them.
If you have a 134a compressor and it will fit a BX, use it as it will save a few hassles long term.
To see if it's exactle the same except gor thre gas used, check the model numbers of both and they should be identical apart from one extra digit on the 134a compressor.
The main problem if different is whether the suction and discharge lines are in the same place as they are expensive to replace and if different it could cost more than it's worth to get hoses that will fit.


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Post by Way2go » Fri Feb 24, 2006 1:19 pm

I've been quoted £58.64 for a R12 to R134a conversion then £75 to test the system with Nitrogen plus a recharge. Pump oils etc are included in the conversion.
They say it is not necessary to change the receiver dryer and this is an expensive part (£38.12 from CAF).
They also say that the treatment used does not reqire seal changes but I think this is a wise diy precaution prior to their conversion.

I am puzzled about the conflictory info about this receiver/dryer and I think we both could do with finding out more on whether and why it should be changed if the aircon experts are saying that it doesn't need to be. I would have thought that they would welcome adding this to the bill if they could justify it.

Although I have this factory fitted aircon, I am still wondering if all these costs justify returning it to operation. :roll:
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Post by Way2go » Fri Feb 24, 2006 1:21 pm

Just re-read my post. The £75 INCLUDES regassing.
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Post by DavidRutherford » Fri Feb 24, 2006 2:00 pm

Way2go wrote:Although I have this factory fitted aircon, I am still wondering if all these costs justify returning it to operation. :roll:
I spent about £220 getting the aircon working on my 405 (new condensor, receiver/dryer and a charge of R413a) and it was worth every single penny in the summer.

But then I suffer from terrible hayfever, and cannot drive for about 6-8 weeks over the summer if I don't have a pollen filter fitted. Of course, to use the pollen filter, you have to have all the windows closed, which then makes Aircon essential. :?
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Post by Way2go » Fri Feb 24, 2006 2:42 pm

Sorry to hear of the hay fever. My aircon worked originally but if it was a nice day it was my preference to adjust windows for good throughflow which is easy on the BX with all electric. Plan works for sole occupancy but if passengers they may object and then aircon wins.
I found the only time aircon was of major benefit is when humidity was high or you are stuck in town traffic.
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Post by mat_fenwick » Fri Feb 24, 2006 11:30 pm

I would definately replace the R/D - it contains a dessicant to remove moisture from the system which loses its effectiveness over time. £38 isn't a great deal of money anyway.

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Post by AlanS » Fri Feb 24, 2006 11:31 pm

Way2go wrote:I've been quoted £58.64 for a R12 to R134a conversion then £75 to test the system with Nitrogen plus a recharge. Pump oils etc are included in the conversion.
They say it is not necessary to change the receiver dryer and this is an expensive part (£38.12 from CAF).
They also say that the treatment used does not reqire seal changes but I think this is a wise diy precaution prior to their conversion.

I am puzzled about the conflictory info about this receiver/dryer and I think we both could do with finding out more on whether and why it should be changed if the aircon experts are saying that it doesn't need to be.
I would have thought that they would welcome adding this to the bill if they could justify it.

Although I have this factory fitted aircon, I am still wondering if all these costs justify returning it to operation. :roll:
I'm afraid your "Expert" air con man is proving to be a defined 'expert' (Ex = 'has been' and spurt = 'drip under pressure')

Speaking as a fully qualified refrigeration and air conditioning mechanic who did a 5 year apprenticeship, gained extended qualifications and worked as a system design engineer and installation overseer for one of the largest contractors in Australia for a while, I can tell you this guy is 100% wrong in what he is saying. You cannot take shortcuts with refrigeration equipment at installation time but more so when conversions are done or whatever you save on the merry go round, you'll lose on the hirdy gurdy and then some.
I "may" be able to scan and send you detailed information from the distributors and manufacturers but it is in very small print and is a weird sized page so I don't know how easy it will be to read, but to condense it into easy to follow steps it basically says:

There are 2 viable options for retrofit: R134a and R401C (Suva MP52)
134a requires a more comprehensive retrofitting procedure which "may" require some component replacements compressors/pressure switches etc.
MP52 or equivalents are less involved to do the change over to due to not running at the high pressures used in 134a. MP52 however will possibly mean a change to nylon barriered hoses due to its high permeation rate.(Loss through pores in the hose.) Nitrile hoses on older cars are likely to be useable with 134a but are unsuitable for the MP52 and varients. Some of these hoses can be very expensive.
Desiccant receiver dryer R12 systems have desiccant XH5.
R134a systems use either XH7 or XH9. Desiccant XH9 is compatable with 134a, MP52 or R12.
O rings: R-12 use NBR (Nitrile)
134a and MP52 High grade Neoprene W or HBNR
O rings to be changed whenever they are disturbed.
Lubricant. PAG used by OEMs for 134a (Some have developed specific PAGs to suit their compressors.
POE - Recommended bu oil suppliers for retrofits. Poly Ester oils whilst compatable with mineral oils used in R12 systems it is still necessary to not only drain the system but to flush it several times. These oils are also highly hygroscopic and extreme care is necessary to prevent moisture contamination of the system.
AB oils require only a small amount to be mixed with the existing R12 oil if conversion is to an MP52 conversion.

To have a system open for any reason and particularly one that has been out of gas for any length of time, a new filter dryer is a necessity not an option more so if it's not one with XH9 desiccant. Running black rubber "O" rings is on par with running engine, gearbox oil or LHM through plain rubber hoses; they rot, then leak.
The dryer's job is to rid the system of any moistre that may have got in. To put this into perspective, I've seen a spot of water the size of a pinhead stop a large butchers coldroom, so in a car air/con it is critical especially when you remember that a car is operating a lot of the time in a polluted and or wet environment.
We buy receiver/dryers out here for around A$65, but if the dryer is incorrect or has been moisture saturated, then to correct the fault, which will possibly show up as an intermittent fault, will again cost you the price of the dryer, plus fitting, plus evacuating the system, purging through with Nitro, drawing into vacuum, leak testing and recharging to rectify it, which makes the cost of the dryer pale into insignificance.
Oil has to be compatable with the gas and components used. Oil in refrigeration/air con systems isn't like it is in a car; it doesn't lie in the sump and make things all slippy. It circulates with the gas and if it is incompatable, then again, it can create all kinds of mystery problems that cost more than the few pence saved when it's converted. Note also, that by leaving the existing dryer in the system is akin to also leaving traces of the incomaptable oil as well as the old gas in the system thereby polluting the entire system when it's commissioned due to the fact that the oil impregnated gas continuously passes through this receiver/dryer, so again it is not only bad policy, it is contrary to good trade practice for several reasons.
I'm afraid with air/con, it's a case of do it right or don't do it.
Personally, I couldn't exist out here without it. I have been having problems accessing equipment to service my 16V so without air/con I just don't drive it in Summer. So much so it has a flat battery now, but in context, a few weeks ago I was in a region in the Xantia where the dash thermometer showed between 42 and 50 degrees for the 10 hours of the journey. Had I been in a car that had been converted using this guys recommendations, I doubt the 5 of us would have survived the trip and it is in extreme conditions such as this where these kinds of shortcuts will find you out.
Whilst I realise you don't get those kinds of extremes over there, even on a 30 degree day, they will still catch you out.
Speify the job is to be done right; if he disagrees, get someone else to do it.
That's professional advice I've detailed above,not heresay and rumours.


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Post by fridgedoc » Sun Mar 19, 2006 7:31 am

Hi DAVID &all

If you have not been convinced by Alan, I can only say "I agree with him 110%" (SEE USER NAME!)

I personally would go down the R413a route, I have converted 100's of R12 systems, thankfully with very few problems, if the job is done properly you should not need to worry about your a/c for a long time and R413a is readily available, the nice thing with R413a is ....................... NO need to change O rings or OIL, and PAG oil is horrible stuff !!

You say "To convert properly", converting to R134a is NOT converting properly it's converting to R134a the same as converting to R413a is just that, converting to R413a ! and as long as the conversion is done properly they both are as good as each other, the big difference is COST, as Alan points out, on the R134a conversion done properly you need to remove compressor drain oil and then flush the WHOLE system, and again as Alan states "the oil does NOT lie in the sump" it mixes with the refrigerant and is present THROUGHOUT the system, APPROX 30% of the oil in the system will be found in the receiver drier, condenser and pipe work, and just to add a little spanner to the works, you should add 10% of the systems oil to the system when you change the drier or condenser something that is quite often forgotten, especially if the system had a leak and lost 10% and the drier is changed 10%, now you are 20% down,
oops!

Listen to Alan........ He knows what he is talking about.

Hope this helps, a/c is great when it's working, and it's amazing the amount of abuse it will take, but there is a point where it will take no more and then it becomes EXPENSIVE.
Bonne Chance

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Post by Way2go » Sun Mar 19, 2006 1:18 pm

Hi fridgdoc, Welcome to the forum & thanks for input.

Are you saying if you use R413a then the conversion cost is not incurred as for R134a. As posted earlier this was not for o rings (not included) but the necessary pipework alterations and additions.

There seem to be high costs associated with this work, can you say whether it is feaseable to do all of this work as a DIY project much more cheaply. Perhaps individually or perhaps if a few of us got together to get the advantage of numbers?

Currently the best costs professionally for R134a have been £75 + 58+ 38+ VAT= over £200 and some DIY pre-work is needed in replacing o rings and the receiver dryer.

What do you think the is cheapest and best way to acheive a working result and how much would you expect it to cost us?
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Post by DavidRutherford » Sun Mar 19, 2006 1:45 pm

As I mentioned earlier, and as re-iterated by mr fridgedoc, R413a is a "drop in" replacement for R12. No need to change oils, no need to change seals, and no need to change receiver drier (unless it's already saturated, which if the system has been open, it probably is)

My charge of R413a in the 405 cost me £70, which was a vac-down for about an hour, and measured re-fill. It's been in for 2 summers now, and about to be used for a third.

My only concern now is that when I got my aircon working, I changed both the condenser and the receiver-dryer, but DIDN'T get any more oil put in to replace what would have come out with those components.

Whilst the system works, and works well, I am now a tad concerned that the system is running a touch low on oil. Mind you, I have a whole R134a system here as spares, so if I do knacker it, it's not the end of the world.
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R413a

Post by fridgedoc » Mon Mar 20, 2006 10:58 am

Hi All

R413a is a "Drop-in" .....NO component changes.

The R12 in your a/c (if there is any) is reclaimed, at this point any repairs should be carried out and it's a good idea to change the receiver/drier, evacuate the system and recharge with R413a, sometimes the tev my need a little tweak to get optimum performance and that should be it !!!
NO draining, NO flushing, NO new "o" rings, NO oil change.

If you paid £70 +vat and you took the car to him, that's a good price, if he came out to you then that's a great price, I know some people think it's a lot of money which it is if the guy does not know what he is doing, if he's a good engineer it's CHEAP...... by the time you take out the cost of the refrigerant his overheads, premises, phone, van, rates, rent, insurence etc he will be lucky to be getting £10 per hr before tax and N.I.

Hope the above helps
Bonne Chance

Stephen

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Post by fridgedoc » Mon Mar 20, 2006 3:21 pm

Hi David

have just re-read your last post, it may be an idea to get the oil topped up,will only take 10/15 mins, should not cost a great deal.

you don't say where you are?
Bonne Chance

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Post by Way2go » Mon Mar 20, 2006 11:09 pm

I spoke to the aircon place that quoted me for the R12 to R134a conversion and asked them about R413a. Guy said that they have to do the conversion so you cant put R12 into it which is illegal. I said yes but do you do R413a which can be used as a drop-in replacement for R12 with same oil type etc?

He got really shirty, said R134a was the only way to go, they don't do R413a and there are not enough R12 cars about to make it worth them considering R413a when they can be converted to R134a. I said OK, lets leave it there...............

I think Alan was right about the definition of expert in relation to this feller.

(Will have to start ringing around to find someone else re R413a)
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