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Carrier condenser unit, loud buzz on start

SlamDunk
SlamDunk Member Posts: 1,291
Hello All,
I noticed our 2011, 16 SEER, 3 ton Carrier condenser unit has an audible buzz on start up then it quiets down after 3 seconds. The buzz wasn't always there, just since last summer. I wouldn't be thinking about it right now if it weren't for the unit not starting on t'sat demand last night (neither fan nor compressor but I could feel fan trying). I replaced the start capacitor and everything fired right up and has been working fine since. Initial buzz is still present. Air temp out of vents is around 65-68 deg F.

It isn't the contactor or loose metal. It sounds like the compressor struggling to start. Is this normal with age?

Comments

  • mattmia2
    mattmia2 Member Posts: 5,562
    did you measure the voltage at the condenser and look at the terminations to make sure one of them isn't loose/burned?
  • SlamDunk
    SlamDunk Member Posts: 1,291
    Terminations look new and felt tight. No discoloration or evidence of burn marks. I didn't take any electrical measurements because it was just prior to bed time and large bugs were flying around my lantern.

    I will measure volts and current draw after work.
  • ratio
    ratio Member Posts: 3,187
    I might throw one of those 2-second acid tests on it also. If it is a start issue with the compressor, it may have gotten things too hot already.
  • SuperTech
    SuperTech Member Posts: 1,792
    If possible test out the dual capacitor if your meter can measure microfarads. You might need a hard start kit if your unit isn't equipped with a start capacitor.
  • SlamDunk
    SlamDunk Member Posts: 1,291
    2 second acid test?

    It can and I will. the cap didn't have any bulge to it. I do not know if it has a hard start kit. None was added after purchase. I have heard bad things about them.
  • ChrisJ
    ChrisJ Member Posts: 12,882
    edited July 2020
    How about a youtube video of it?

    Is this a 2 stage scroll compressor?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • SlamDunk
    SlamDunk Member Posts: 1,291
    I don't have one but this is comparable. Line set goes up 12 feet and over 8 ft.


  • ratio
    ratio Member Posts: 3,187
    https://www.johnstonesupply.com/storefront/product-view.ep?pID=B13-043.

    I try and always have a few of these on hand, to help me decide if I'm going to throw the digital manifold on a system, or not.

  • SlamDunk
    SlamDunk Member Posts: 1,291
    edited July 2020
    ratio said:

    https://www.johnstonesupply.com/storefront/product-view.ep?pID=B13-043.

    I try and always have a few of these on hand, to help me decide if I'm going to throw the digital manifold on a system, or not.

    I think I'll pass. That's above my ability.

    @ChrisJ It is not a 2 stage compressor.
  • ChrisJ
    ChrisJ Member Posts: 12,882
    SlamDunk said:

    ratio said:

    https://www.johnstonesupply.com/storefront/product-view.ep?pID=B13-043.

    I try and always have a few of these on hand, to help me decide if I'm going to throw the digital manifold on a system, or not.

    I think I'll pass. That's above my ability.

    @ChrisJ It is not a 2 stage compressor.
    How are the compressor mounts?
    All screws and bolts tight?

    Any tubing rubbing on something it shouldn't?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • SlamDunk
    SlamDunk Member Posts: 1,291
    I'll have to check compressor mount bolts in the day light. Negative on everything else.
  • unclejohn
    unclejohn Member Posts: 1,757
    Is it a Bristol compressor. Give complete model number.
  • SlamDunk
    SlamDunk Member Posts: 1,291
    Well, it sounds worse than I remembered. So much so that my wife was concerned enough to send me a video.



    Condenser unit is. 24ABC636A003

    Ill be home to dig deeper in an hour.
  • SlamDunk
    SlamDunk Member Posts: 1,291
    The video sounds worse than in person. Cant hear it from ten feet away. The cap died last night as measured <1microf. Volts 120 to ground, 240 ph to ph. Running load amps to compressor is 8A on each leg. Everything nice and tight. I'll add rubber pads under it. Sits direct on pad.

    I'm going to call it normal operation and move on to my next problem. Appreciate the suggestions!
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,024
    Contactor loose connections hard start kit
  • mattmia2
    mattmia2 Member Posts: 5,562
    What about maybe burned contacts in the overload from when it wasn't starting with the bad cap?
  • SlamDunk
    SlamDunk Member Posts: 1,291
    Contactor is fine.. actually, i replaced it a month ago for this buzz.. steady volts on top and bottom. The cap literally failed and found within an hour of failure