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How to tell what refrigerant is in the 308GT4 A/C system

Discussion in '308/328' started by Ian Bishop, Sep 25, 2018.

  1. Ian Bishop

    Ian Bishop Karting

    Dec 3, 2017
    156
    Forgive my ignorance on this one - I'm sure there's an obvious answer and I've tried scanning prior A/C related posts to no avail.

    I have never topped up / recharged the A/C in my 1975 GT4 since purchasing it. But it doesn't feel quite as cool as it did in the past, so time for a top up. In California all the top-up cans are r134a. I gather the car originally came with r12, and that the oil used within the system would be different depending on the refrigerant used. The A/C system has had the more current adapter affixed (see photo) but how do I know what is in there and if still the older r12 how do I obtain some as obsolete? Old service records show 'recharge' and 'affix A/C adapter' but these are as detailed as I can find. Not sure if the picture helps!



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  3. thorn

    thorn F1 Rookie
    Silver Subscribed

    Aug 7, 2012
    2,884
    Tallahassee, FL
    Looks like r134 connectors. R12 is threaded on the outside. So I'm going to bet the system contains 134.
     
  4. absostone

    absostone F1 Veteran
    Silver Subscribed

    Jul 28, 2008
    5,627
    Yes depends on the connections
     
  5. Ian Bishop

    Ian Bishop Karting

    Dec 3, 2017
    156
    I assume you recharge / top up via the "Suction" side / drain side. The blue safety cap does screw on - would it be helpful to post a picture of that attachment without the safety cap or would that not change your guidance?
     
  6. thorn

    thorn F1 Rookie
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    Aug 7, 2012
    2,884
    Tallahassee, FL
    The r134a system is refilled from the low pressure line. I can't quite tell from your photo (can't see your tubes), but in my car the low side has the blue cap. (However, you don't go only by the cap color.) The definitive way to choose the low side: it has the larger tubing.

    Having said all of that, I don't recommend this as a home-DIY. A professional shop will have the proper equipment and techniques to get the best results; using a can of refrigerant from NAPA isn't. I had mine done for less than $60 at a local mom/pop AC shop, and am happy with the result.
     
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  8. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Rossa Subscribed Owner

    May 4, 2001
    31,328
    Birmingham, AL
    Full Name:
    Tommy
    It did have R12. It was "converted" to 134.

    Simply charging it with 134 after fitting different connectors is not a proper conversion. As time goes by you will continue to leak the 134 so be prepared for that.

    If that were my car I would just buy a can from AutoZone and recharge it myself based on where you are with it now.
     
  9. Steve King

    Steve King F1 Rookie

    Feb 15, 2001
    4,366
    NY
    1st I ASSUME that it was converted based on the quick connect fitting adapters that are shown in your picture. Un less you jury rig a hose set you couldn't put R12 into those fittings. But not knowing the history of who filled it I would take it to an AC shop where they have a freon tester kit which will tell them what freon type is in the system. Now if you assume it is 134 then put a set of AC gauges on the system and check pressure when running. Read the AC pressures vs temperature and fill to the correct pressure. Put an AC temp. gauge in your center duct with system on full fan and take a reading. It should be somewhere around 40*.
     
  10. Ian Bishop

    Ian Bishop Karting

    Dec 3, 2017
    156
    Thanks everyone for your input. I was actually able to track down the Dino specialist who original did the work on it & with the guidance / comments from this forum I was able to ask the correct questions. They confirmed it had been fully converted to r134a - system drained, refilled oil/freon, connectors changed etc... So I went ahead and use the AC PRO system - easy to do - had pressure gauge (with pressure range set by ambient temp).. process was easy to do and A/C is now blowing much cooler. Followed instructions fully - including use of safety goggles and gloves.. necessary because the can does get cold! Total time about 15 mins.

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  11. DonB

    DonB Formula Junior
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    Nov 11, 2003
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    Florida
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    Don Bartz
    Nice looking engine compartment. Good for you!
     
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