1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Dear Guest, Official Club stickers are now available, if you have not already ordered some go grab them now! To order click this Link ----> CLICK ME Go get them whilst stocks last! To dismiss this notice click the cross to the right of this message.

R12 refrigerant conversion to what?

Discussion in 'Engine' started by Apial, Sep 24, 2004.

  1. Apial

    Apial Hardcore MB Enthusiast

    Messages:
    738
    Joined:
    Aug 20, 2004
    Car:
    300ce-24 sportline,BMW i3 Rex
    What is the current acceptable gas that is used as a replacement for systems running R12a? I mentioned R49 to one local firm and they said no to that one. They said they used R134a in conjuction with a special extra type of oil that sat on top of the standard oil. I was told that R18 and R49 gases would destroy the rubber seals if left in contact over-winter, and that they were no longer used.

    Is this true? Is £120 to convert a reasonable price?
     
  2. marcos

    marcos Hardcore MB Enthusiast

    Messages:
    1,299
    Joined:
    Oct 6, 2003
    Location:
    Hertfordshire
    Car:
    ML 320CDI W164
    I've just been studying refrigeration gases but I can't remember. :eek:

    I'll check on monday morning
     
  3. Andy W

    Andy W Hardcore MB Enthusiast

    Messages:
    401
    Joined:
    Jun 27, 2003
    Location:
    Stoke on Trent
    Car:
    ML 270 cdi
    I have been using R49 for 7 years now, no problems at all. You can also use RS24.
     
  4. marcos

    marcos Hardcore MB Enthusiast

    Messages:
    1,299
    Joined:
    Oct 6, 2003
    Location:
    Hertfordshire
    Car:
    ML 320CDI W164
    According to the charts R12a ( auto ) should be replaced with R134a.
     
  5. Andy W

    Andy W Hardcore MB Enthusiast

    Messages:
    401
    Joined:
    Jun 27, 2003
    Location:
    Stoke on Trent
    Car:
    ML 270 cdi
    You can "retrofit" an existing R12 system but you must do the following. Remove the compressor, drain the oil out, refit the compressor, rig up a run round pump to flush the mineral oil out, charge with syntetic oil, dehydrate system and recharge with R134a. Run the system for a few hours, reclaim the gas out of the system, remove a sample of oil and check the mineral content of the synt oil, if above recommended doseage, repeat the above again. You will also have to replace the filter drier twice as well as fitting R134a tap connectors over the existing 1/4" flare fittings. That is the correct way to do it and it is very labour intensive, I was retrofitting as early as 1993. The other method is to just recharge with R49 without removing the oil, this gas will work with mineral and synthetic oils and is now a good proven gas, I have used it daily in all aspects of refrigeration for years with no problems or noticable drops in performance. If you retrofit without carrying out the following you will destroy the system by blocking it up with sludge, and mineral oil and synthetic oil separates and one floats on top of the other like water on oil, I have seen many compressors destroyed by this.
     
    1 person likes this.
  6. Will

    Will Hardcore MB Enthusiast

    Messages:
    9,708
    Joined:
    Jan 21, 2003
    Location:
    Surrey
    Car:
    2004 S211 E55K AMG/1988 190E 2.3-16/1988 190E 2.5-16/2003 Porsche 911 3.6 Carrera 2 (345hp Powerkit)
    I also believe that by mixing R12 and R134a without following the correct evacuation procedure as described by Andy can cause over-pressurisation problems. Apparantly as the gases mix, it can cause anomylous readings on the pressure monitoring equipment, leading to damaged seals/other components as the extreme pressure tries to find an escape route! :eek:

    Watch out for the cowboys who just wanna make a quick buck filling your system for £50, without checking for leaks etc first! :devil:

    Cheers,

    Will
     
  7. marcos

    marcos Hardcore MB Enthusiast

    Messages:
    1,299
    Joined:
    Oct 6, 2003
    Location:
    Hertfordshire
    Car:
    ML 320CDI W164
    We have air-conditioning engineers fully trained working with us now and I'm just starting to learn about it, out of curiosity really. It is amazing the bad practices employed by some of these cowboys.
    As Will says just watch out for the cowboys, I've already come up against a few in the short time I've been studying it.
     
  8. OP
    OP
    Apial

    Apial Hardcore MB Enthusiast

    Messages:
    738
    Joined:
    Aug 20, 2004
    Car:
    300ce-24 sportline,BMW i3 Rex
    Thanks for the help!

    Thanks for your replies. R134a looks like a no-no for me. An engineer is recharging the system with a R12 replacement "drop-in" refrigerant that is happy to run with mineral oils and importantly my existing rubber seals. He might well be using R46, but I'll post back. Hopefully he will not find a significant leak.

    The car has only traveled 400 miles in the last 2 years, and I can see a gas/liquid mixture flowing through the inspection glass. Lost gas has probably leaked gas past the compressor shaft seals, and fairly slowly too, considering that there is still some left. Fingers crossed an evacuation/pressure test and recharge will be all that is needed.
     
  9. OP
    OP
    Apial

    Apial Hardcore MB Enthusiast

    Messages:
    738
    Joined:
    Aug 20, 2004
    Car:
    300ce-24 sportline,BMW i3 Rex
    Good news, the engineer says that due to the car being stood 2 years, the gas has leaked through the compressor shaft seal. The leak was tiny, and by using the car again it should reseal. He extracted 80g of R12 and replaced it with 990g of R49 and the a/c is cooling down to about 8C.

    He suggested that I should run the a/c in the winter by at least pressing in the demist button once a week for 10 minutes.

    Cost was £74 + Vat with a home visit.
     

Share This Page