On Tuesday, June 5, 2018 at 1:12:29 PM UTC-4, Scott Frederick wrote:
Thanks for the info.
I'm still waiting for a repeat of the symptoms to do an actual voltage check.

When the compressor/fan wasn't running the thermostat was showing cooling on.
There's no compressor operation and no fan operation. Even after power cycling at the fuse box and thermostat (delay). I can look down on the unit condenser fan through a window within 5 seconds of the thermostat kicking on cooling.

But the air handler is running when this problem happens, right?
Just no compressor and condenser fan, right?



So most likely it's a contactor, since the thermostat has power without the batteries during the event, and is intermittent (cycles fine for hours or days before failure) right?

If the air handler is running, that's one possibility. But
it could be other issues too. You start with the simple, easy ones.