A/C re-gas

[Ray Duffy]

After acquiring my H '91, 300sl a few months ago I knew I would need to treat it to some TLC. After fitting a new ragtop and updating the lights, I finally decide to get the A/C working. My Horror, the gas used in older cars is no longer available!

Any help would be greatly received

Regards

Ray Duffy


(Edited by Ray Duffy at 5:26 pm on Aug. 6, 2002)


(Edited by Ray Duffy at 5:27 pm on Aug. 6, 2002)

 

[Andy]

Hi Ray

Give me a ring on 0121 558-4848. From your profile you are in Warwickshire not far from us in B'ham.

We can convert it from the R12-R134a for you.

Regards

Andy @ www.mercedesservicing.com

 

[Richard Moakes]

I would suggest you contact an aircon specialist or a Mercedes specialist like Andy.

R134a is not the only option, you can use R406a which is a direct substitute for R12.

There are many options, all of which will cost you a reasonable amount of money and may have better or worse long term prospects.

How long do you intend to keep the car? If it is a long time, then I would change the receiver/drier and condenser to R134a specification, change O rings to the newer type compatable with the new oil and refrigerant, flush the entire system to remove the old oil, and then refil with R134a and PAG oil.

IF you resize the condenser properly, and make sure the auxilliary fans work properly then 134 can be almost as effective as R12.

Good Luck

Richard

 

[JR]

BE CAREFUL WITH R134, I HAD THIS DONE AND IT LEAKED LIKE A SIV, APPARENTLY IT HAS A MUCH SMALLER MOLECULAR SIZE THAN R12 AND THEREFORE LEAKS OUT PAST THE ORIGINAL SEALS.
I MANAGED TO FIND A FRIENDLY AIR CON MAN WHO GOT ME SOME R12 AND REPLACED THE R134 ALL FOR £30
TROUBLE IS I NO LONGER HAVE A NUMBER FOR HIM
ANYWAY BE CAREFUL .
I HAVE NO EXPERIENCE OF R406A SO CANT COMMENT.

REGARDS

JR

 

[MarkSL]

I had the same problem with my K plate 300SL !
I took it to an aircon specialist who checked out the system. The clutch was not engaging due to a wiring fault but the system was still charged !

15-20  minutes later the system was running ice cold again  - for £30  

 

[Andy]

Hi All,

I see there is a couple of missconceptions cropping up.

1. There is no other refrigerant that is legal other than 134a. There is no substitute for R12. What a lot of people do NOT take into account that some of these other substances have not been or have been tested in crash scenarios and have been found wanting. Ie, they help in certain conditions to proprogate a fire. It has been known for insurance companies to throw out a claim due to incorrect refrigerant being used.

2.In the vast amount of cases 134a dosn't cause a problem to any of the seals or condensor or evaporator.

The biggest problems that we face in the industry. Is that you the consumer. Decide not to repair the AC when it stops working. Then after its stood idle for a long period of time. Get said AC repaired. Then due to moisture getting in, things like expansion valve seizes,compressors don't work or are noisey. Then complain its going to cost a fortune to repair. The biggest enemy of the AC system is moisture. Thats the job of the receiver dryer. That bottle like thing with a window on it. This should be changed every four yrs or so. In practice it is never changed or not changed unless there is a specific problem. This acts like a sponge. So there is a limited life time. Do not get me wrong. A lot of the time the system is recharged and away we go. But sometimes I wonder if at times the system would be a little more responsive if this was changed.

Now for those wondering if your vehicle has the new refrigerant (gas to the layman!!!). The new refrigerant came in about 1992. So some Jreg cars will have it and certainly K reg onwards should have the R134a more healthy for the ole ozone layer refrigerant. The R12 was outlawed Jan of this year. We were one of the last countries to do so.

So don't let anybody fit any spurious refrigerant to your AC systems.

Also as a final recomendation. If you are having any work done to your AC system. Make sure they fit a Ultra Violet dye (UV) dye to the system. The main problems experienced is that after a couple of months the AC sytem stops working due to the loss of refrigerant. Then the argument starts. Since to find a leak the system has to be recharged. And who pays? We the UV dye fitted then there is a high likely hood that if there is a leak from the system, it will have pulled the dye out with it. Thereby making life a little easier when searching for the leak. If under the bonnet it should be easy to find with the aid of a UV lamp. If the evaporator is suspect (the AC matrix behind the dash) then there is a likely hood of the dye being washed out with the water (a natural by product of the AC system) through the drain hole over the tunnel area underneath the car.


I hope this helps with some of the frustration and confusion surrounding the AC system.

Regards

Andy @ www.mercedesservicing.com

PS. Make sure they fit a UV sticker under the bonnet to show somebody else its fitted. Then somebody else can check for leaks with out first recharging the system. Thereby saving YOU money!!!!

 

[simon]

Nice one Andy,highly educational & helpful, thank you
Ernest.Sidesman

 

[Richard Moakes]

I can't let this become a one sided discussion.

Firstly, R406A is not illegal, it is a HCFC which is currently legal for service in existing equipment, not for any new installations. Check DTI site for details of cutoff dates for use of HCFC's.

There has been much debate as to the US EPA approval for MVAC use of R406a, most of which seems to revolve around flammability. It contains 4% isobutane, is weakly flammable only after significant dilution, such as a long term leak which ought to be noticed by the user of the system.

If we have to debate the likely chance of an explosion following an accident, surely we have to take the flammability of petrol into consideration, which presents a greater risk of explosion than any leaking refrigerant.

I offered R406a as a cheap alternative for anyone who might not want to keep the car long term or spend significant sums of money on a retrofit.  Whilst it is true that a well designed system will offer reasonable cooling when converted to R134a, it is also true that there is a likelyhood of disappointing performance if the condensor is not upgraded and the higher head pressures are likely to find any weak points in an old system.

I don't want this to become a religious war, but statements about spurious refrigerants is a bit strong and it would be better to allow informed debate?

I know people who are charging systems with R406a right now, and who have very satisfied customers who whilst they may not know the intricacies of CFC/HCFC blends they are appreciative of a cost effective and safe alternative to R12.

Ask yourself this, when did you last see an article in a national newspaper or Watchdog about cars exploding due to 'spurious' refrigerants?

I can't agree more about lack of serving of A/C systems and the unwillingness of most people to change receiver dryers or go to the expense of UV dye in the system. In all my vehicles, past and present, I have always changed the receiver / dryer regularly which combined with the regular vacuum testing for leaks has undoubtedly saved me large sums of money by eliminating the need for replacement compressors.

Regards,

Richard

 

[dave elcome]

Richard.

You seem to know what you are talking about, but i would still recommend to the rest of the members to heed Andy's advice, after all he runs his own MB garage, and therefore by default, knows his stuff!!

One last thought................we have yet to prove him wrong!!!

 

[MarkSL]

Dave

Not wishing to disagree with anyone, I just say check out the system first. I automatically assumed that the compressor wouldnt engage due to a leak/lack of pressure in the system.

Having proved it was just a simple wiring fault, I now have nice cold aircon again, without draining or refilling the system or arguing which refrigerant to use

Mark

 

[MarkSL]

Dave

Not wishing to disagree with anyone, I just say check out the system first. I automatically assumed that the compressor wouldnt engage due to a leak/lack of pressure in the system.

Having proved it was just a simple wiring fault, I now have nice cold aircon again, without draining or refilling the system or arguing which refrigerant to use

Mark