Contactors and circuit resistance

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Old 07-29-19, 05:58 AM
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Contactors and circuit resistance

I have a question about understanding what I should see with an installed contactor. I have a single pole switched unit in my Ruud. Across the terminals on the input side (with disconnect pulled out) I see an open circuit as expected, but on the output side I do not see an open circuit across those terminals. Am I supposed to see a non-open circuit across these points?
 
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Old 07-29-19, 06:26 AM
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You say installed contactor. If your wires are conneccted on the output side (T1, T2) you would be reading motor/compressor winding resistance. So no, you would not see an open circuit.
 
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Old 07-29-19, 06:59 AM
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Thanks. That's what I figured but I wasn't too sure. So it might be, for the motor, on the order of 110 Ohms or so.
 
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Old 07-29-19, 07:02 AM
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Hi, what is it your trying to accomplish?
Geo
 
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Old 07-29-19, 07:34 AM
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At this point, just looking to understand what I should be seeing here. I have my Ruud installation manual at home somewhere. I'm looking for it to take a look at the schematic, but I figured I'd ask in the meantime.
 
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Old 07-29-19, 04:45 PM
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Making resistance checks at the contactor doesn't tell you anything.

You measure for 240vAC to the input side of the contactor and 240vAC to the output side when the contactor is closed.

To check the fan..... you remove the wiring and check its resistance. Same thing for the compressor.
 
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