E73; E74; 1. Turn off the main power to your HVAC system at your breaker. Your HVAC system can have multiple breakers so make sure to turn them all off before moving on. Once the power to your whole HVAC is off, check your furnace and fan. Make sure there are no lights that might indicate your system still has power.

Troubleshoot thermostat power issues during hot weather (E3, E4, E23, E24, E73, E74, or E195 help codes) 5 of 10 Troubleshoot a "No power" alert on a Nest thermostat (E298, E448 or M20 help code)

Troubleshoot thermostat power issues during hot weather (E3, E4, E23, E24, E73, E74, or E195 help codes) 5 of 10 Troubleshoot a "No power" alert on a Nest thermostat (E298, E448 or M20 help code)

These steps cover the following help codes: E3, E4, E23, E24, E73, E74 or E195. If your Nest thermostat suddenly started showing one of these codes during the hot summer months, visit the following link to learn how to help fix it: Troubleshoot E3, E4, E23, E24, E73, E74 and E195 help codes; Troubleshoot Matter issues

Note: The instructions in this article apply to heating and cooling systems common in the United States and Canada.

Note: If your thermostat won’t turn on, or if your Nest Thermostat E or Nest Learning Thermostat (3rd gen or earlier) is having power issues, learn how to troubleshoot when your Nest thermostat won’t turn on.

Estos pasos son aplicables a los siguientes códigos de ayuda: E3, E4, E23, E24, E73, E74 y E195. Si tu termostato Nest empieza a mostrar uno de estos códigos durante los calurosos meses de verano, consulta cómo solucionarlo en el siguiente artículo: Solucionar problemas con los códigos de ayuda E3, E4, E23, E24, E73, E74 y E195

To fix unconfigured or unspecified wires: In the Home app, go to your thermostat Settings Thermostat Wiring Update Wiring or Wire Configuration.

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