(Fixed) No Power to Rc Wire Detected e73 Nest

Here are effective solutions to fix the ‘No power to Rc wire detected’ e73 error on your Nest thermostat. Find step-by-step troubleshooting methods that work!

If you’re here because your thermostat is giving you a bit of trouble. You see, I’ve been around a few times when it comes to common issues like the frustrating “No power to Rc wire detected. Learn more at nest.com/e73” error. Nevertheless, I’m here to guide you through some solutions that might just save the day.

What Does e73 Mean on Nest Thermostat?

This little hiccup usually pops up when your thermostat isn’t sensing the electric juice flowing through your Rc wire. Here are possible reasons behind this error:

• Low Voltage on Rc Wire: The Rc wire might not be receiving sufficient voltage. This could be due to issues with the power supply or connections.
• Dirty or Clogged Air Filter or Drip Pan: A dirty air filter or drip pan can affect the airflow and overall system performance. This disruption might lead to power-related errors like e73.
• Clogged Drain Tubes: Blocked drain tubes could cause complications in the drainage system, affecting the thermostat’s power supply and triggering the e73 error.
• Burnt Fuse: A burnt fuse can cut off power flow and trigger the e73 error.

How to Fix Nest No Power to RC Wire Detected e73 Error

Inspect the Wirings

If your Nest thermostat is flashing that e73 error and saying it’s not getting power through the RC wire, here’s something simple you can do to fix it: Check the wiring. 

Here are the steps you need to follow:

1. Turn Off the Breaker: Start by turning off the breaker that powers your HVAC system. Make sure all related breakers are switched off.
2. Remove the Display: Take off the thermostat display to see the wires. Find the Rc wire and disconnect it. Don’t touch the other wires. Make sure your thermostat is set to heat only.
3. Check the Rc Wire: After removing the Rc wire, look at it closely. Copper should be visible on the wire, appear straight, and not painted or corroded.
4. Test the voltage of the wire: Use a voltmeter to check the Rc wire’s voltage. The voltage should be steady along the wire. If it’s over 24 VAC, the Rc wire is good. The issue might be with the system itself, which can be common during hot summers.
5. Put back the Rc wire: If the Rc wire is fine, put it back into the connector. Press down the thermostat’s connector button.
6. Check the Other Wires: You can do the same voltage check for the other wires. Turn on the breaker and reattach the thermostat. You have to wait until it turns on.

Check the Air Filter of the Thermostat

A blocked air filter often leads to this issue. Making sure that your HVAC system receives plenty of airflow is key to its performance.

When your air filter gets clogged, it reduces the airflow over the coils. This can lead to freezing on the cooling coils, potentially shutting down the system.

Here’s what you can do:

1. First of all, you need to locate the air filter for your Nest thermostat at the back of the grate,  near the walls or on the ceiling.
2. In the case that the filter is inside the furnace, start by turning off the breaker. 
3. Then, if you see a dirty or clogged filter, have it replaced. 
4. If the issue is frozen cooling coils, allow them to defrost naturally before using them again. 
5. Remember, change your air filter on a quarterly basis to prevent such problems from cropping up.

Check the Condition of Drain Tubes and Drip Pans

The drip pan and drain tube in your system work to remove frozen water. If they get blocked, water can build up.

When this happens, your heat pump or AC might shut down to prevent overflowing water. Consequently, your HVAC system won’t supply power to the Nest thermostat, leading to the Nest no power to Rc wire detected e73 error.

Here are the steps to fix the problem:

1. Turn Off the Breaker: Start by turning off the breaker to deactivate the HVAC system. If there are multiple breakers, make sure to switch them all off.
2. Locate the Cooling Coils: The next step is to locate the cooling coils on your thermostat. The user manual can guide you to their exact place. If the cooling coils are behind a sealed panel, avoid removing them. Doing so could cause problems with the system’s functionality.
3. Inspect the Drip Pan: Check if the drip pan underneath the cooling coils is dry. Moreover, ensure the drain tubes connected to the drip pan are not blocked. If you discover water, there could be a blockage within the drain pipes. If there’s no water but you see rust, it suggests there was water present that has dried up.

Refer to your HVAC system’s user guide for assistance in clearing water or clogs. This process can vary, so following the guide will help you navigate it correctly.

Check the HVAC Fuse

In the summer, when the temperature rises, your AC system goes into high gear. But sometimes, all that hard work can lead to a burnt-out fuse in your system. When that happens, power gets cut off to the thermostat from the HVAC.

Here’s what you can do:

1. Turn Off the Breakers: Start by switching off the breakers. The first priority is safety.
2. Locate the Fuse: Next, look for the fuse under the HVAC system’s control board. If you’re not sure where it is, consult your user’s guide for its location.
3. Inspect the Fuse: Check out the fuse closely. If you spot any weird marks or colors that shouldn’t be there, it’s time for a replacement.
4. Swap the Fuse: Once you’ve found the culprit, replace the fuse. Make sure you put back any panels you removed.
5. Switch On: Turn on the breakers again and let the cool airflow.

Contact Nest Customer Support

So, you’ve given it your best shot – tried all the solutions for that Nest no power to Rc wire detected e73 error, yet nothing seems to work. That’s alright. 

When none of the fixes seem to do the trick, don’t hesitate to reach out to Nest’s support team. If you speak with them, let them know what you’ve done so far. Share the methods you’ve tried to tackle the issue.

By sharing your troubleshooting steps, you’re helping the support team understand what you’ve been through. This way, they can give you the best guidance to crack the code on your Nest thermostat.

So guys, now you’ve got a bunch of handy tricks up your sleeve. These steps can help you get rid of the annoying no power to Rc wire detected e73 error on your Nest thermostat. 

If this article came to your rescue, don’t hesitate to spread the word! Share it with others who might be facing the same Nest thermostat errors. We’re curious to know which method did the trick for you, so drop a comment below.

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Frequently Asked Questions (FAQs)

What is RC wire on Nest thermostat?

The Rc wire on a Nest thermostat is a power-supply wire that connects to the cooling side of your HVAC (Heating, Ventilation, and Air Conditioning) system. It provides the necessary electrical power for the cooling components of your HVAC system, such as the air conditioning unit. The Rc wire is one of the essential wires that enables your Nest thermostat to control both heating and cooling functions, allowing you to maintain a comfortable temperature in your home.

Why is my Nest saying no power to RC wire?

Your Nest thermostat might display a “no power to RC wire” message because the wire isn’t properly connected. Another possible reason is that the wire was incorrectly entered in the app settings. In order to resolve this issue, ensure that the system wires are connected properly and securely. Remember, it’s essential to turn off the system before inspecting the wires to keep yourself safe.

How do I fix the RC wire on my Nest thermostat?

To fix the RC wire issue on your Nest thermostat, begin by checking the RC wire connection. Turn off the power to your AC unit for safety. Locate the HVAC air handler’s condensation drain line and the associated overflow switch. Remove, clean, and inspect the switch. Ensure the drain line is clean. Test and flush the drain line. At last, replace the switch and restore power to your HVAC unit.