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e73 code with heat on

Jmicheal11
Community Member

‎12-04-2023 10:52 AM

Nest thermostat is a couple years old, doing some remodeling and turned off heat, the battery died on thermostat, I turned off breaker at main panel,charged using usb cable, and adapter and now get e73 message. Safety switches are clear and no water in them. Got power to unit but not to thermostat

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zoeuvre
Community Specialist
Community Specialist

‎12-07-2023 02:53 PM

Hi Jmicheal11,

 

Yikes! I'm sorry to hear that your thermostat is giving you E73 error code. Let's see what's going on. A few questions:

 

  1. Are you located in North America or Europe?
  2. What type of heating, ventilation, and air conditioning (HVAC) system do you have?
  3. What troubleshooting steps have you done before contacting Support?
  4. Who installed the thermostat?
  5. Do you use a single-wire or double-wire transformer? If single-wire: Is the thermostat connected to the heating or the cooling system?

 

Also, check on the following (take note to turn off the power breakers before touching any wire on the thermostat): 

 

  1. Go to the breaker box and check if the breakers flipped. If yes, reset the breakers.
  2. Check your system’s drip pan or drain tubes (skip this step if you only have a heating system).
  3. Check the condition of the HVAC fuse.
  4. Check if you have an energy savings box near the electric meter (possibly near their air conditioner).
    • Search for a small box with 2 lights on it (one light is red, the other is usually green). This box allows the utility company to cycle the customer’s air conditioner off and on during certain peak times of the day.
  5. Check your air filter.
  6. Gather the power readouts of Battery, VOC, VIN, and lIN of your thermostat.
    • Go to Settings > Technical Info > Power.
  7. Make sure the thermostat wires are properly stripped and seated in the thermostat base.
  8. If there’s a common wire connected in the C terminal, remove it.
  9. Move the RC wire to the unused RH terminal.
  10. If the previous thermostat is available, install it.

 

Keep us posted. We're happy to help.

 

Best,

Zoe

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