AC compressor noise | FerrariChat

AC compressor noise

Discussion in '308/328' started by Iain, Sep 19, 2013.

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  1. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,257
    UK
    I was driving down the motorway a few days ago & it was hot so after a while I stopped & put the roof back on & carried on with the intention of running the AC. The AC on my car works reasonably well & behaved as its supposed to, cutting in & out.

    I've put additional sound deadening (dynamat) in the car over the last couple of years so sometimes I find myself hearing things that seem different. On this occasion every time the AC clutch engaged I could hear a whirring noise which stopped when it disengaged.

    Beginnings of a bad bearing in the compressor or just the normal noise the compressor should make when its running?
     
  2. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,257
    UK
    Try the question a different way :)

    When you run the AC in your 308/328, can you hear the compressor running? ( assuming a std exhaust!)
     
  3. Steve King

    Steve King F1 Rookie

    Feb 15, 2001
    4,367
    NY
    I never hear it running but I know when its on due to the drag on the motor. Also I find it interesting that your compressor "cycles" considering how poorly the system functions. To do that implies you reached the level of cooling that is set on the AC knob. I have never seen that happen even with a freshly charged system. Usually a cycling compressor is a symptom of an under charged system.
     
  4. spirot

    spirot F1 World Champ

    Dec 12, 2005
    14,501
    Atlanta
    Full Name:
    Tom Spiro
    mine cycles too... thougth it was charged properly... it gets nice and cold!
     
  5. jfrazar

    jfrazar Karting
    BANNED Rossa Subscribed

    Jun 26, 2004
    223
    Savannah, GA
    Full Name:
    Joe Frazar
    Cycling in normal and the noise you are hearing might be normal. My mondial and 328 have a slight noise almost like a very muted compressor noise when the clutch is engaged. Normal based on location of compressor and the cockpit. Ac that does not cycle is not working correctly. AC System that is function correctly will eventually freeze the evaporator. This is why it needs to cycle off and on. If the ac system is not working correctly, IE Lazy expansion valve ect. the compressor will never cycle.

    Joe Frazar
     
  6. andyww

    andyww F1 Rookie

    Feb 7, 2011
    2,775
    London
    #6 andyww, Sep 20, 2013
    Last edited: Sep 20, 2013
    Mine (328) was cycling even when driving in record temperatures we had in the UK earlier this year, nice and cool. When the compressor is running there is a sound which reverberates down the pipes so its not really coming from behind but from everywhere. Its a faint whirring kind of noise.

    On the subject of noises, I would guess our RHD cars sound quite different for the driver to LHD cars. There is probably more of this A/C sound. There is also more intake noise which is great. Another sound very prominent especially at certain revs is a gear whine which is (I think) the cam belt lower pulley drive gears. I would think this is louder for the drivers on a RHD car.
     
  7. FasterIsBetter

    FasterIsBetter F1 Veteran

    Jul 22, 2004
    5,844
    NoNJ/Jupiter FL
    Full Name:
    Steve W.
    On my 328 (LHD), the simple answer is yes, but it's not very noticeable. Have you lifted the engine lid and listened to the AC compressor cycle on and off up close and personal? That would more likely tell you whether it is functioning properly or starting to have problems. You should hear the click when it turns on, and the sound of the clutch engaging, and then the compressor working. If it is really loud or is making any odd sounds, you might want to have an AC professional take a listen. Some noise is normal. Too much noise is not. Without actually hearing it, it is hard to say if yours is normal or showing signs of problems.
     
  8. pippo

    pippo Formula 3

    Sep 25, 2005
    1,913
    FL
    Full Name:
    pippopotemus
    Joe,

    Im sure you mean the above for ferrari comps. Not strictly true for all compressors. Variable speed comps do not cycle at all. Just different design.
     
  9. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,257
    UK
    Thanks for all the replies, a good consensus seems to be that it probably would/should be audible.

    Ran it again today & its more noticeable at higher engine speeds - which is hardly a surprise. It doesn't sound bad, I guess I just never noticed it before but I don't use the AC that much so maybe not a surprise.

    It definitely should cycle in & out, mine does about 15-20secs on & about 30 secs off - depends on engine speed and air temp. Its working pretty well really.

    When it doesn't cycle is an indicator of low gas levels in the system IME. Eventually the LP switch will stop the compressor cutting in at all ( and there will be lots of bubbles in the sight glass on the drier).
     
  10. pippo

    pippo Formula 3

    Sep 25, 2005
    1,913
    FL
    Full Name:
    pippopotemus
    iain, tip- try to run the ac at least once a week. Winter or summer. If, like you said, you hardly run it, thats not good for the system. Gotta run it once a week! prevents the freon from oozing out, and keeps things /seals lubricated.
     
  11. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,257
    UK
    Good advice & indeed I do run it every time I drive the car for the exact reason you mention- but only for a couple of minutes usually just to keep everything moving. Same with the heater valves, vent flaps & electric windows - in fact anything with a motor in it (even the ariel when I remember!)

    I reckon the best upgrade that's been made to my AC system to stop it leaking was a pair of brass valve caps with rubber seals in them on the hi/low ports instead of the usual plastic ones. Since those went on its stayed pretty much full as far as I can see.
     

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