A/C won't turn on

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Old 03-20-20, 01:35 PM
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A/C won't turn on

First hot day of the year and my spouse call down from upstairs that the A/C isn't working. Did some startard troubleshooting. Not an expert, Just trying to figure out what is happening.
First check was the capacitor, a 30/5 which seems to test fine. It is only a couple of years old.
I have AC power at the relay but nothing after the relay so relay isn't opening when A/C demand on.
Checked 24V to the relay it is 0V. Just to be sure, I check the 2nd AC unit and as expected when AC demand is on I have 24V.
So no 24V from the controller in the furnace. This is the AC in the attic so haven't sen everything up there yet but I do know the blower is running. Assuming I don't have a cut wire (unlikely) what would be the troubleshooting steps on the controller board to figure out why I am not getting 24V out to the compressor?
I am going to continue to dig in on this but wanted to get the question out there in case I found nothing obvious.
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Old 03-20-20, 02:46 PM
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Will I was able to figure it out. It wasn't a cut wire but the the wire from the thermostat for Compressor on (in my case yellow) was broke off at the terminal strip. Knock on wood, I think my spouse will be happy.
 
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Old 03-20-20, 03:43 PM
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Good find.

I was going to add more troubleshooting steps.
 
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Old 03-21-20, 04:47 PM
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I won't claim any special knowledge. I am lucky that I have 2 very similar A/C units So I was able to do voltage comparison at the compressor, thermostat and controller board in the furnace. Once I got to the controller board,I was lucky that the wire was clean broke off so I could see that the wire was loose.

Honest the DoItYourself forums are my go to place for help!
 
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