Tried the AC a few days ago and got “y1 wire error e103” on my NEST thermostat indicating that there was over current on the Y1 wire used to turn on the AC.
TL:DR - I replaced the contactor in the outside unit and it fixed the problem.
I used my ammeter to connect Y1 and the Red 24VAC wire. The outside unit turned on and I measured 340ma on the circuit. After having the HVAC technician troubleshoot the issue, he determine it was a problem with the NEST thermostat. I replaced the thermostat that evening and it reported the same issue. I searched Amazon and found a contactor that looked similar and had the same ratings for $15. I installed it a couple of days ago and it has worked since.
The new contactor measures 340ma also. I’m not sure why the NEST thermostat had issues with the old contactor. Maybe the old contactor current spiked when initially activated - something that my meter wouldn’t catch.
Wires used on my HVAC
Previous contactor - worked fine manually but NEST thermostat reported over current.
New thermostat installed - NEST has no issues with it.