Contactor Bouncing or Hammering

Hello,

I have looked at a few units in the past where the contactor for the compressor has constanly bounced when power is applied to the coil to bring on the contactor. I have changed the contactor in the past and this has cured the problem. But sometimes it hasn't and the PCB has been faulty or the compressor What causes the contactor to bounce? Is it the coil no longer producing the same pull or can the current passing the contactor somehow effect the coil? The power to the coil has not been fluctuatiing on my testers.

Any help is greatfully received.

in general, if the coil is causing the contactor to chatter, it usually means, in the absence of controls fault, that the coil connections are loose/corroded. sometimes i have found dry connections on pcbs that only show up on visual checks and do not show as voltage fluctuations.

Quote:

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Originally Posted by charlie dart

The power to the coil has not been fluctuatiing on my testers.

Any help is greatfully received.

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Have you also looked at the neutral connection?

Contactors invariably chatter if the supply voltage drops below the pull in threshold, or the neutral connection is loose/corroded. (Assuming mains voltage) The volt drop can be caused by various things, one of which is loose connections.

Contactors 'buzzing' while pulled in is a sign that dirt/swarfe has found it's way into the inside of the coil.

Quote:

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Originally Posted by frank

Contactors 'buzzing' while pulled in is a sign that dirt/swarfe has found it's way into the inside of the coil.

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Learn something new every day!

There was me thinking that it needed hitting with something till it stopped buzzing :confused::D

Next time i get the chance i'll take a buzzy one apart and see what gotten in there.

Jon :)

Careful Jon, in your case it just might be cow s**t!! :D

Thanks guys that has helped. I shall look forward to my next chattering contactor and take a good look at it

Thanks again.

When the contactor is energised by LP pressure control, check the contacts. I have seen this a few times and it was caused by bad contacts in the pressure control.