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High Side vs. Low Side Fittings on Compressor?

Discussion in 'Mondial' started by Albert Penello, Apr 1, 2020.

  1. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
    162
    Woodinviille, WA
    Full Name:
    Albert J Penello, Jr.
    Was going to try and put some refrigerant in my system to check the status of my AC. Unlike most old R12 systems I've seen, both fittings are on the compressor and both have the same sized threaded fittings.

    Does anyone know which of the fittings is High Side vs. Low Side? The "Upper" fitting (closest to the front) has as slightly smaller line so I assume that's the low side.

    I can't seem to find this specific number anywhere.

    Anyone who has done an R-134 conversion I'd love to hear.

    Thanks!
     
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  3. theunissenguido

    theunissenguido Formula 3
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  4. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
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    No it is not. The smaller fitting is the high pressure side. The larger fitting is low pressure side and is for charging.
     
  5. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
    162
    Woodinviille, WA
    Full Name:
    Albert J Penello, Jr.
    So both fittings/connections are the same size on my compressor. The hose going to the forward/upper fitting is slightly smaller diameter than the lower, larger hose.

    So be clear both fittings are the same, it's the hose sizes which are different.
     
  6. yelcab

    yelcab F1 World Champ
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    R12 system has same fittings. The smaller hose is the high pressure side.
     
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  8. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
    162
    Woodinviille, WA
    Full Name:
    Albert J Penello, Jr.
    Yeah even looking at the diagram, the image of the gauge (I) is a low-pressure gauge.

    I ordered some 90 deg R12 adapter fittings and will throw some refrigerant in and see what happens!
     
  9. theunissenguido

    theunissenguido Formula 3
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  10. spicedriver

    spicedriver F1 Rookie

    Feb 1, 2011
    2,601
    I would put a new drier in first. It's possible that material could come out of the old drier and clog the refrigerant lines.

    Also, refrigerant usually leaks out of O rings. If you're serious about getting the system working, you should replace all the O rings you can find. You can get these in a generic kit with a bunch of different sizes. Likely the old compressor is going to have seals that leak, and needs to be replaced. The system should be evacuated with a pump before you add refrigerant, and the correct quantity of oil.
     
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  11. Albert Penello

    Albert Penello Karting

    Jul 21, 2019
    162
    Woodinviille, WA
    Full Name:
    Albert J Penello, Jr.
    All good advice. I actually have a professional Robinair AC diagnostics and recharge machine. So recharging the system is basically free for me. Given that, my method for a car like this (based on many of my 30+ year mechanic friends advice) is to charge up the unit first before breaking old seals. This system has probably been unused for a decade and my have naturally leaked out over a time like that. So I pull a vacuum for 30min, let the system hold for 10min, then fill with refrigerant and dye. If those tests pass it will let me know the overall condition of the system faster then chasing down o-rings that I may have distrubed.

    If the system takes (and holds) the charge then I'll start a more thorough component change little-by-little replacing o-rings, driers. etc.
     
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  13. greatscott73

    greatscott73 Karting

    Sep 1, 2017
    233
    West central Florida
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    Howard Scott
    When I got my car a year ago, the A/C was inoperative. I knew the car had just had a belt service, so I assumed the compressor had been removed at the time, and no new charge had been added. I bought a few cans of vintage R12 off of ebay and filled up the system and it has worked fine ever since. I remember getting to the port was a pain. I'm pretty sure I had to do it through the wheel well access. IIRC, I attached the fill hose to the port with the larger hose, assuming it meant lower pressure. As you can readily tell, I'm not an A/C expert, but it has continued to work through one hot Florida summer. Maybe I just got lucky, lol.
     
  14. JLF

    JLF Formula 3
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    Sep 8, 2009
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    Anyone know where the ports are on a Mondial T? I can see the blue capped port next to compressor but I can’t find the red capped port.


    Sent from my iPad using FerrariChat.com mobile app
     
  15. FerrariJB

    FerrariJB Karting

    Jun 8, 2019
    62
    Netherlands
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    FerrariJB
    Thanks for the York Manuel. I now know how to check the oillevel
     
  16. greatscott73

    greatscott73 Karting

    Sep 1, 2017
    233
    West central Florida
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    Howard Scott
    This might help. It’s the fitting lowest and closest to the engine that I used. As you can see, it has”SUC” cast into it, so I assumed that meant suction. This is an 87 3.2.
    Image Unavailable, Please Login
     
  17. yelcab

    yelcab F1 World Champ
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    Next to the compressor, under the car. Yes, really accessible.
     

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