A/C won't shut off when it reaches desired temperature

Probably the thermometer.

Mine is doing the same thing. If it still runs after checking the thermostat then your control board in the unit in your attic either has a loose or broken wire. This is not expensive to fix so don’t let them rip you.

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You need to have a competent tech troubleshoot the system an not just throw parts at it.

I’ll disagree that a control board is “cheap” by the time you throw in labor, trip charge, supply house run, and return repair time.

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somebody repairs HVAC units

It could still be the thermostat. Take the thermostat off the wall while it’s running. If the unit cuts off then it’s your thermostat. If it still runs like mine is then it’s your control board/relay switch.

You don’t have a bad control board it’s just the relay is defective or there is a loose wire. Sometimes you can just hit the relay and “unstick” it.

Thanks for all the responses

On wet days like this it's because the thermostat is frozen because the unit is sucking in too much moisture. Put a tarp over it and run it on high and once it thaws it will shut off

Had the same problem when I bought a foreclosure.Previous owner rewired it so the fan ran constantly when the board went bad.
Replaced the control board.
Bought on Amazon for $100
Easy install

And buy some spare capacitors