Error E72 No power wires detected

[Dessertgirl25]

I received an error code E72 on my thermostat. We checked the wires and replaced the fuses in the AC unit. The AC still will not turn on. I can't even get to the regular screen to try and just cycle the heat on so I can make sure it on the AC. Do you think it can just be the thermostat or the nest wiring no good anymore?

[GBD]

Try checking for a stuck float / bad water sensor/ blocked drain in the condensate drain path of your AC unit. Many units will remove power from the thermostat if they detect a problem with this drain.

[luciaaa]

Hi, @Dessertgirl25,

Thanks for reaching out to the community. I understand the E72 error code on your thermostat can be frustrating. I'll do my best to help you find a solution.

To better assist you, I have some questions related to your thermostat:
 

• What type of thermostat do you have? 
• Would you mind sharing a photo of your wiring configuration?
• Do you have a conventional or a heat pump system?
• When did your system last receive a professional maintenance check?
• When did the issue start?
• Did you experience any power outages recently?

In the meantime, I recommend:

• Check that the power breakers are on.
• Check if your system’s drip pan or drain tube is full of water or has a clog.
• Check that all the wires are properly stripped and seated in the thermostat base.

Keep me posted.
 

Best regards,

Ana.