A/C contactor help

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Old 07-29-17, 09:08 PM
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A/C contactor help

Central AC works fine but will not shut off at desired temp. New thermostat and the heat works fine so I do no think it is that. Someone mentioned the contactor switch so I think I will try that next. Can someone point me in the right direction for a replacement? The pic is what is in there now. Thanks in advance.

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Last edited by PJmax; 07-29-17 at 09:17 PM. Reason: reoriented picture
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Old 07-29-17, 09:20 PM
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Welcome to the forums.

Your picture was hijacked.

When the contactor is supplied with 24vac.... that center piece where the red arrow is gets pulled in to activate the condensor.

It doesn't look like it's engaged/in now.

You can carefully remove the slide on wire in the picture. If the contactor opens and the A/C shuts down.... it's not the contactor.
 
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Old 07-29-17, 10:34 PM
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Why not diagnose the issue, instead of throwing parts at it.
Do you have 24 V on the coil wires?
 
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Old 07-30-17, 08:17 AM
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'Made in USA' contactor. Have not seen that for a long time. Clean it up (use a blower, don't touch it, high V electricity there), spray some WD40, see if that work.
 
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Old 07-30-17, 10:18 AM
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"spray some WD-40" ........ Spray it where..... not on a contactor.
 
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Old 07-31-17, 06:35 AM
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with a little wd40, the contact button may pop up.
 
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Old 07-31-17, 02:24 PM
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Contactor seems to be fine as it engages/disengages. Starting to think it may be an inside the house issue as the fan continues to run when on auto and on. I have to shut the whole unit off to shut the fan off.
 
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Old 07-31-17, 03:28 PM
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Ok.... you posted the contactor so we assumed it was the outside condensor that wouldn't shut off.

If the inside blower won't shut off then it can be a thermostat issue or control board problem if it's the type with timed blower operation.

A make and model of the inside unit would be needed for further help.
 
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Old 07-31-17, 06:39 PM
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I thought it was an outside problem at first. I will get the other info tomorrow. Thanks for the help.
 
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Old 07-31-17, 06:51 PM
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Its a Miller, Model 901998
 
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Old 07-31-17, 07:28 PM
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That looks to be the part number for a replacement blower unit.

The actual air handler/furnace model number is needed.
It will be much longer and have numbers and letters in it.
 
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Old 07-31-17, 09:23 PM
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If inside blower does not stop, then contactor is not your problem. Did you say your thermostat is new ? and work fine only with heat ?? You may want to check to make sure it is wired correctly for AC. If thermostat is fine, then the only other problem that I can think of is going to be the control board. But check thermostat first, do one step a time.
 
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Old 08-01-17, 01:28 PM
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Thermostat was hooked up and running fine before this happened. I have another one that I tried and it did the same thing.




As far as the model number, they put a bracket over it and I can not move the bracket to read all of it. Serial number is fine, just the model # is covered.

Thanks again for all the replies.
 
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Old 08-01-17, 03:59 PM
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Removing the thermostat from the base takes it out of the equation. If the blower was running with the thermostat removed.... it's not the stat.

So if the ID tag is covered by a bracket then you have an A/C air handler.... not a furnace.

If you disconnect power and remove the wiring access cover..... you may be able to get the part number off the fan control board or relay.
 
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