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Do you have reson to believe there is missing power to the unit?
Have you verified with a voltmeter that power is missing?
Basically the outdoor unit is doing nothing?
And is the indoor blower running?
If you listen very carefully to the outdoor unit, do you hear a hum?
At the indoor unit...do you know if there is a water safety switch that cuts power in the event of a plugged condensate drain.
Here is a boring speech....
There are 2 different power sources that make the outdoor unit run. 220v sits at a bridge (contactor) waiting to cross. The thermostat runs off 24 v to make things run like the furnace and ac.
The 24 v gets sent out to the ac unit to close the bridge for cooling...if the 220v is missing due to blown fuse or breaker there is commonly a buzz coming from from the closed bridge.
When no sound at all is heard it generally means the contacotr (bridge) is not closed.
I am afraid this will involve a voltmeter to see if the 24v is there, the 220v and start seeing where the issue lies.
The is a way to manually press the bridge down to test but it must be done with power on and 220v present.