Air Cond. Compressor Clackity Clack | FerrariChat
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Air Cond. Compressor Clackity Clack

Discussion in 'Technical Q&A' started by BOKelley, Oct 23, 2009.

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  1. BOKelley

    BOKelley Formula 3
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    #1 BOKelley, Oct 23, 2009
    The air conditioning compressor on my 86 Mondial produces a rather strange sound upon a cold start and then disappears as the engine warms up. At first I misdiagnosed the source of the noise, I thought is sounded much like the rhythmical crack of an arc from a bad spark plug extender to ground, only louder. But upon not finding any bad extenders on the front bank, I got to looking elsewhere and with my automotive stethoscope, found that the noise seems to be coming from the bowels of the compressor. The noise can be best described as similar to the slap of a leather strap (bringing back childhood memories of when I was a bad boy) and it is on a steady cadence, varying with rpm.

    To add a bit more info (and maybe some confusion), when cold, the noise is present with or without the AC turned on. When engine warms up with the AC off, the noise is absent until I turn the AC on whereupon it reappears. When the AC has run for awhile, the slapping noise again subsides.

    Any one else experience this phenomena? Is it as simple as maybe the drive belt slapping against a hidden support that is induced by the extra load from a cold bearing?

    Thanks,

    Brock
     
  2. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #2 PAP 348, Oct 23, 2009
    That is a strange problem you have there by the sounds of it mate. :):)

    How tight IS the a/c belt? Does it need adjusting maybe? :):)

    Id still say your compressor is ****ed, but I would confirm 100% before you order another one. :):)

    Noise in the engine compartment can be VERY tricky at times. You think you've found it, but then you realise its something else. Doh!! :p:p
     
  3. maurice70

    maurice70 F1 Rookie

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    #3 maurice70, Oct 23, 2009
    Its probably just the belt,either the A/C or alternator,,I had this on my GT4.It only made a noise on start up for a few minutes and after I replaced all belts it went away.
     
  4. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #4 PAP 348, Oct 23, 2009
    Did it make a 'squealing' noise or a 'clackity clack' noise like this fellow's Mondial? :p:p
     
  5. KKSBA

    KKSBA F1 World Champ
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    #5 KKSBA, Oct 23, 2009
    I had it once on my Mondial, same symptoms (clakety-clack goes away on warm up, comes back when you engage the AC). It was the belt that needed some adjusting.
     
  6. BOKelley

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    #6 BOKelley, Oct 23, 2009
    Thanks.....The belt seems reasonably tight and I cannot see that it is flopping around on the topside. No squealing either. I think I need to pull the wheel and have a look from the underside to be sure. And with that said, I could remove the belt and see if the sound persists...that should narrow things down a bit.

    Brock
     
  7. pippo

    pippo Formula 3

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    #7 pippo, Oct 23, 2009
    Try rubbing a bar of soap along the inside edges of those belts/suspected belts. This trick improves the sometimes whining/slipping/squealing sounds of belts.

    Now if it is slippage and not squealing, you can tighten. But if this still does no good, apply some acetone to those inner surfaces with a brush. This will help it grip beter, guaranteed, guys! Another trick.....
     
  8. BOKelley

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    #8 BOKelley, Oct 24, 2009
    ....went out this morning bright and early to re-evaluate the problem and decided that it would be simple to tackle the easiest route first. The V-belt tension seemed to be on the tight side so I loosened it to provide about 1/2" deflection. Started Miss Behave'n up and problem solved, no more slapping sound with AC on or off. Still a bit concerned as to why it was making the sound in the first place but will worry about that if she begins to act up once again.......

    Brock
     
  9. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #9 PAP 348, Oct 24, 2009
    Thanks for the update Brock! :):)

    So the belt had TOO much tension on it!! Interesting! :):)

    Glad you got it sorted mate. Enjoy! :):)
     
  10. KKSBA

    KKSBA F1 World Champ
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    #10 KKSBA, Oct 24, 2009
    I had no cold air on my Mondial so when I had the compressor replaced I had this clackety sound. Took it back and they adjusted the belt and it was gone. I think I remember it was too tight, rather than too loose.
     
  11. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #11 PAP 348, Oct 24, 2009
    Very good sir, an over adjusted belt seems to the cause of that noise here also. :):)
     
  12. tazandjan

    tazandjan Three Time F1 World Champ
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    #12 tazandjan, Oct 24, 2009
    Brock- Those belts' tension should be set using a tensiometer. That will ensure everything is correct with no guessing. Otherwise you can wear out bearings or belts very quickly. WSMs tell you how to do it, but you are better off having someone who knows what they are doing install and tension them. New accessory belts are not that expensive.

    Taz
    Terry Phillips
     
  13. pippo

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    #13 pippo, Oct 24, 2009
    Good point. However, I understand one can get by well without a tensiometer. You do need to know how much tension in pounds to apply to a point, say, with a scale/stick, then meanwhile measure distance with ruler of specified movement. Dunno about Ferrari shop manual, but my Alfa says it well. (hey, Enzo started at Alfa, eh??)
     
  14. BOKelley

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    #14 BOKelley, Oct 24, 2009
    Thanks Pap....BTW, I just returned from a business trip to Kalgoorlie in WA....my first trip to your fine country....I need to come back for some sailing!

    Cheers,

    Brock
     
  15. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #15 PAP 348, Oct 25, 2009
    Fantastic Brock! :D:D

    Glad to hear you enjoyed your visit mate. :):)

    Must have been something mining related I take it?? There is nothing else in Kalgoorlie! :p:p
     
  16. alberto

    alberto Formula 3

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    #16 alberto, Oct 25, 2009
    The noise you heard from your belt is likely due to the belt itself. They have some sort of plastic reinforcement in those belts and over time, the plastic hardens and makes the clacking noise. As the belt heats up, so does the plastic and hence the noise goes away after the car warms up a bit. Simple remedy is to replace the belt with a new one until it returns again.
     
  17. BOKelley

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    #17 BOKelley, Oct 25, 2009
    Thanks Alberto, sounds like a very plausible reason for the source of the sound....will find a replacement to see.
     
  18. BOKelley

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    #18 BOKelley, Oct 25, 2009
    Yes it was mining related....mining, mineral processing and extraction is my life :)
     
  19. PAP 348

    PAP 348 Ten Time F1 World Champ
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    #19 PAP 348, Oct 25, 2009
  20. moysiuan

    moysiuan F1 Rookie
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    #20 moysiuan, Oct 26, 2009
    I suspect the belt is a bit stale/old and while re-tensioning can make a difference, or putting some belt dressing as a temporary solution worked, after about 4 years, the plastic in the belt loses flex and it slaps/crackles?, quite alarmingly, mostly but not exclusively when cold. I change belts every five years (with car in cold storage four months of the year), but now do the a/c belt every two, and check the tension of the others while "in there". I use a krikit tensioner, simply device, push with a finger until a click, widely available, and when I had belts done professionally years ago, the tension per the clicker was accurate to the required specs, so it seems accurate and repeatable.

    http://www.midwayautosupply.com/pc-7821-221-gates-krikit-v-belt-tension-gauge-91107.aspx
     
  21. mike

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    #21 mike, Nov 3, 2009
    Had the Exact same noise on my 308 2v...it was the A/C compressor clutch...

    Best wishes,
    Mike
     
  22. Earthboundmisfit

    Earthboundmisfit Formula Junior

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    #22 Earthboundmisfit, Nov 3, 2009
    There was an AC unit on ebay for the 328/3.2 Mondial (listing 120476998253, over now). I contacted the seller, it was still available as of yesterday. It's off a 17k mile Mondial and was working when it was removed. Seemed pretty reasonably priced at $379.

    (I'm NOT affiliated with the seller, just thought it might be of interest to some here (maybe OP) because AC is frequently not working on our cars).
     

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