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RTU 12 ton - Blower Motor Contact is rapidly clicking in and out.. & low volt transformer to hot

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There is on of two things happening...either the contactor is going bad (coil) and it is pulling too much current causing the transformer voltage to drop... or the transformer is going bad causing the contactor not to hold in because of low voltage...

Pull the wire from the contactor and check the transformer voltage...if it is a 24v transformer then the static voltage should be like 26-27 vac...then ohm out the coil and check that it is not shorted...

Also check incoming voltage to make that is not low... it could compound and cause a low transformer voltage...

Sometimes the easiest way to find the exact cuase is to either change the contactor... (I often just plug a new one in and see what happens before installing it) or the transformer... so you can see which one is the problem...


Posted on Jan 03, 2011


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