Top 5 Ways To Fix No Power to RC Wire Detected E73

No Power to RC Wire Detected E73

Google’s Nest Thermostat Program is undoubtedly one of the top programmable thermostats available in the market. Suppose our E73 Nest Thermostat does not receive any power to the Rc wire.

It can also be caused by low voltage from the RC wire to the air filter and a clogged drain tube. First, we need to check that there is at least 24 VAC voltage on the RC wire. No Power to RC Wire Detected E73 Because our wiring, air filter, and HVAC fuse are not all working properly.

If our Nest Thermostat RC is showing no power to the wire and an E73 error is detected. We can replace it with a clogged air filter or drain tube and drain any water into the drip pan. Setting up and using the Nest Thermostat is a very simple process. Most problems that are easily solvable can be fixed.

The problems with the Nest Thermostat look like this. The Nest Thermostat turns off automatically, the screen appears black, and the air conditioner does not cool the house. If the E73 Nest Thermostat does not receive any power from the RC wire. This could also be due to the low voltage in the RC wire.

The most common cause of no power in the E73/RC wire appearing on the Nest Gen3 display is due to the AC outdoor unit/compressor shutting down, which in turn shuts off power to the Nest Thermostat.

What Is Error E73?

At first, an E73 error can seem like a pretty serious problem because it brings our Nest thermostat down completely, rendering it useless until the error is fixed. Because of this, our Nest Thermostat does not cool down. And we have to face severe weather like summer.

Simple problems like checking the AC breaker box and checking that the AC breaker is on should be tried to solve on our own. Materials like cooling coils and drip tubes in ACs are quite difficult to test, so it is suggested that we take the help of an expert.

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RC Wire Not Getting Power Due to E73

When the Nest e73 detects that there is no power in the RC wire. So there is less voltage in the wire. There may be a clogged air filter in the system, or there may be water in the drip pan.

After draining the water from the drip pan, replace the clogged air filter, and we need to check if there is a high voltage in the RC wire. If our Nest thermostat shows something wrong, there could be many reasons. Some of these reasons are given below.

  • Low voltage on RC wire.
  • The presence of water in the drip pan.
  • Clogged drain tubes.
  • The fuse is burning.

Replacing a Nest thermostat or any other HVAC system can be very costly. So you should try to troubleshoot as much as you can. If we fail to find a way to troubleshoot an issue, please let an expert do the work for us.

Check Your Thermostat Wiring

Check Your Thermostat Wiring

The most common Nest Thermostat problem that causes an E73 error could be an improper or insecure connection. There are some steps you can follow to check your wiring.

  • Turn off your breaker first.
  • Then disconnect your HVAC system from power.
  • There may be multiple breakers throughout the circuit of our HVAC system, so it is important to know that they are all off.
  • Then in order to reveal the wires connected to the breaker, we need to detach the Thermostat’s display from the base.
  • Switching the Thermostat to heat-only mode while retaining all other wires disconnects the RC wire.
  • Then check by removing the RC wire.
  • It has to be checked that it has 1mm of copper open, and the copper should not be crooked. It is also necessary to know that the wire does not rust.
  • By using a voltmeter, it is necessary to test the RC wire as it has to be checked whether the power voltage of the RC wire is equal or not.
  • A 24 VAC voltage decides whether our wiring is correct or not. And the problem occurs only near the AC unit. This is normal as many AC units fail due to hot temperatures during summer.
  • Then make sure the connector button is pressed down as the wire needs to be inserted back into the Nest connector.
  • In order to be fully processed, we can perform similar checks on other wires.
  • Then turn your breaker on again to bring the power back on.
  • Then insert the Nest Thermostat back into the base and wait for a while for it to back up.

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Check the Air Filter Connected to Your Nest Thermostat

Check the Air Filter Connected to Your Nest Thermostat

There can be another common problem with the Nest Thermostat, and that is a clogged air filter. Maintaining proper airflow is essential for our HVAC systems to function properly. A clogged air filter limits the speed of air coming through the cooling coil so that it can exit the system.

Here are some steps below to check your air filter, and we can use them.

  • The first thing to do is locate the air filter on your system, which is usually mounted behind a mesh along the walls or ceiling.
  • The air filter may be inside our AC, so we should turn off the power at the breaker.
  • If the filter is clogged with dirt, it should be replaced with a new filter.
  • When the problem is with clogged cooling coils, do not reuse the coils. If you want to use it again, it is best to defrost it first.

It is recommended to change the air filter once every 80 to 90 days to prevent this type of problem.

Check the Drain Tube/Drip Pan for Your HVAC

Check the Drain Tube/Drip Pan for Your HVAC

Sometimes, a clogged pan or drain tube that is thought to be carrying dirty water to an HVAC system can clog the Nest thermostat, allowing water to be backed up.

When this happens, our AC or heat pump turns off to prevent water overflow, causing our HVAC system to stop sending power to the Nest Thermostat, and it displays an E73 error. No Power to RC Wire Detected E73 Because our wiring, air filter, and HVAC fuse are not all working properly.

Below are some steps to check the drain tube/drip pan for your HVAC.

  • First, turn off the breaker and also turn off the power to the HVAC system.
  • If there are several more breakers in the system, check that they are all turned off.
  • Then find the cooling coils.
  • If the cooling coils are placed next to a closed panel, do not remove the panel yourself, as the device system may not function properly without a seal.
  • The drip pan is always found under the cooling coil, which is attached to a plastic drain tube.
  • It is important to check if dirty water has filled the pan and that the drip tube is not clogged.
  • If we get water, it signals that there may be a blockage.
  • We need to look for any signs of water damage, such as rust which first indicates the presence of water.
  • You can get help cleaning clogged drip tubes online or by using your HVAC system water guide.

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Check Your HVAC Fuse

Check Your HVAC Fuse

If seen, the AC has to work harder in the summer season. Sometimes running the AC for a long time can burn the fuse. This can cut off the power supply from our HVAC system to the Nest Thermostat. And the AC can be turned off. No Power to Rc Wire Detected E73 as this may have caused a power cut from the HVAC system to the Nest Thermostat.

To solve this problem, follow the steps below 

  • First, the breaker must be turned off, and the power to the HVAC system must be cut off.
  • Then we need to locate the HVAC fuse on the HVAC system control board.
  • If we disagree on finding a solution to this issue, we need to refer to our owner’s manual.
  • Then we need to check the fuse.
  • If the fuse burns out or fades, it is damaged and needs to be replaced.
  • After replacing the fuses, check that we’ve reattached any panels you removed before turning the HVAC system back on.

Contact Nest Support

Contact Nest Support

Well, the E73 error can be fixed with the help of the above steps to fix it. But if none of them work for us, it indicates a problem with our Nest thermostat. In that case, we would have to think about contacting Nest customer support and telling them about your problem.

It is important to check whether all the various troubleshooting steps we have mentioned have been implemented. This helps the Nest customer to get a better understanding of the problem they are facing. And they allow us to get the help we need so much.

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Frequently Asked Questions

Frequently Asked Questions

Why Does My Nest Say No Power to RC Wire?

The loose connection of the wire is mainly responsible for this happening. This can also mean that the connections made by you in the app are incorrect. Check that the system wire is properly inserted or not, and always turn off the system while checking the system wire; otherwise, any kind of damage may occur.

How Do I Fix Nest Error E73?

The reason for this error on your Nest Thermostat is that the RC wire is not getting any power. To fix this problem, check your wiring, air filter, drain tube/drip pan, and HVAC fuse to ensure they are all working properly.

What Is the RC Wire on a Thermostat?

If there is no Rh wire in your system, then the RC wire works as a power wire for both of you. Heating and cooling systems. If you have RC and Rh wires, the RC wire is your power wire.

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