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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22515
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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We have a message on our Nest thermostat that says: "E23

Customer Question

We have a message on our Nest thermostat that says: "E23 wiring Report
No power to Rc wire detected." What does this indicate? I hear the fan running, but the air feels cool.
Submitted: 1 year ago.
Category: HVAC
Expert:  HVAC Guru replied 1 year ago.

Hello and thanks for using this service, if you have been waiting do not worry or get upset I am just one of the techs on here and I try to get to as many customers as I can and I just picked up your question now. Please give me time to respond sometimes I get your replies late so there may be a delay in my response.

That means that either you have lost the 24 volt supply or you do not have a wire connected to the C terminal on the unit. If you do not have a wire connected to the C terminal you would then need to charge the thermostat every so many days or that will happen. If you do have a wire connected to the C terminal at the thermostat, go to the furnace and get to the main board in the furnace. There should be a 3amp SLOT FUSE on the board in the furnace, if that is burned out that will cause that issue,

We are on the honor system for our time, all I ask is please rate my service using the STAR RATING LINK on your page before you leave. If you are not happy with the service please let me know before leaving a negative rating. This is the only way I am paid or credited through the site for my time. This will also allow you to get directly back to me for FREE follow up questions and tips are greatly appreciated! Thanks

Customer: replied 1 year ago.
Thank you, ***** ***** call the furnace repair people and have them check.
Expert:  BillyHvac replied 1 year ago.


The more realistic issue is that the furnace has run on limit or tripped a roll out switch. Limit is caused by lack of air flow, dirty filter, bad blower etc.

Constant fan (cool air) with no communication to thermostat is 99% tripped furnace safety. If you choose to move forward to check a few things I can help.


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