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Are there orings in the air conditioning gas hose from evaporater to compressor

Discussion in '365 GT4 2+2/400/412' started by Dazanz, Mar 6, 2019.

  1. Dazanz

    Dazanz Karting
    Silver Subscribed

    Jan 24, 2015
    83
    New Zealand (Queenstown)
    Full Name:
    Daren
    The gas has leaked out and I have lost pressure in my air conditioning system.
    I have recently refitted the evaporater unit under the dash and the regasing only lastest a week.
    I did the fittings up nice and tight and didn't see any orings but my air conditioning expert is saying that all modern cars have them
    If there's no orings should I add Hylomar non setting joint and gasket compound or the something
    Thank you for any help
    Daren
     
  2. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,820
    Austin TX
    Full Name:
    Brian Crall
    O rings yes.

    Sealant no.
     
  3. raemin

    raemin Formula Junior

    Jan 16, 2007
    318
    Lyon (FR)
    Full Name:
    R. Emin
    I am on the same boat... My car was refiled with R134a and the proper fluorescent stuff, and even if the pressure remained quite acceptable, one could notice quite a few small leaks here and there. So if you are not on the stock gas, be prepared for some "reasonable" leakage. The double air-conditioning (such as featured in the 412 and optionally installed on the older models) is even more delicate.

    To answer your question, roto-locks connectors (without o-rings) were widely used in R12 AC systems, these have been discarded as the connectors with o-rings do provide a better seal for thinner gas (such as 134a). In our cars there is a mix of fittings: the compressor and condenser do rely on roto-lock fittings (so no o-tings), but my dryer has o-rings. I have not disconnected the evaporator yet, but the fittings do look like roto-locks (no o-rings).

    Whenever the fitting do have an o-ring, fixing a leak is as easy (replacing the o-ring). For roto-locks, an o-ring cannot be retrofitted, but a sealant (such as "leak lock") can be used sparingly. Unlike modern parallel flow condenser, the serpentine condenser is less prone to be clogged by a sealant, same story regarding the "piston" compressor. So if things go wrong this will not be as bad as in a modern AC system.

    If I were to use sealant, this would be as a last resort, and I would replace the dryer after a short while (the dryer filters the debris). This is a cheap part (reportedly the same unit as used on early Saab 900 8valves)
     
  4. Dazanz

    Dazanz Karting
    Silver Subscribed

    Jan 24, 2015
    83
    New Zealand (Queenstown)
    Full Name:
    Daren
    Thanks for the reply raemin. I really don't believe I saw any orings so I will remove the centre console and unscrew the hoses from the evaporater to confirm and I guess my only choice is to sparingly use some pipe joint compound.
     
  5. raemin

    raemin Formula Junior

    Jan 16, 2007
    318
    Lyon (FR)
    Full Name:
    R. Emin
    There is also some sort of connector on the firewall between the cabin section and the engine bay. For know I could not figure out whether this is a split or rigid connection (does not look like roto-lock though). You could give it a look and report...

    Regarding sealants, if pipe joint compound does not do the trick, you could also try sealant additive. These can be very nasty, but the ones that are supposed to rejuvenate rubber could be worth a look. By contrast the moisture / polysiloxane / "solid seal" variants can clog the system and most AC shops will not touch your car for fear of clogging their own system, so better to avoid these types of sealants. There is an old paper on the subject :

    Leak Sealers PART1
    Leak Sealers PART2

    You should also ask your air conditioning expert for the UV additive, at least you will now for sure where the leak is. They can even refill the system without cooling gas (some sort of cheap nitrogen instead), so you can test the system without leaking 2kg of harmful 134a in the environment...
     
  6. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,201
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    My '84 400i is stock A/C and all connectors I have seen have o-rings. Just FYI.
    Ken
     
  7. Newman

    Newman F1 World Champ
    Professional Ferrari Technician Owner Consultant

    Dec 26, 2001
    13,254
    Canada
    Full Name:
    Newman
    Dont forget to use the R134a compatible pipe dope.
     

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