Your Nest thermostat can say delayed during a normal HVAC startup pause, but recurring delays can signal inadequate power or a wiring problem. Leave the temperature setting unchanged and allow the system to start. If the countdown repeatedly restarts or heating or cooling never begins, check the thermostat’s power information and connections.
Use the model-specific steps for your Nest Thermostat (2020), Nest Thermostat E, or Nest Learning Thermostat (3rd or 4th gen). The wiring, C-wire, and compatibility checks apply to compatible North American installations.
The short version
- Wait first: Some HVAC systems have a built-in startup delay of five minutes or more.
- Check recurring delays: Repeated countdowns can indicate inadequate power and need further troubleshooting.
- Match your model: Charging, battery replacement, and menu paths differ between Nest models.
- Fix the power supply: A C wire or compatible Nest Power Connector may resolve persistent power problems.
| Check or fix | When to use it | Model or condition |
|---|---|---|
| Allow the startup delay to finish | An ordinary countdown | All current models |
| Allow the compressor diagnostic pause | A countdown from 30 minutes | Compatible air-conditioning or heat-pump installations |
| Read equipment and wiring information | A delay accompanies a power alert | Nest Thermostat and Learning 4th gen in the US and Canada |
| Check battery and incoming power | Recurring delays or low power | Thermostat E and Learning 3rd gen |
| Inspect information in an app | You need battery or device details | Supported Google Home or Nest app models |
| Review operating history | Scheduling may explain the behavior | Use the app or device path for your model |
| Restore HVAC power and close the cover | A no-power alert or N260 after connector installation | Nest Thermostat and Learning 4th gen |
| Repair wire connections | Loose, bent, or corroded wire ends | Current North American models |
| Reseat the display | Accompanying power or startup trouble | Learning Thermostat and Thermostat E |
| Connect or repair a C wire | Recurring inadequate power | Compatible North American installations |
| Install a Nest Power Connector | You need an alternative to a new C wire | Compatible 24 VAC systems |
| Review the Power Connector product page | You need accessory and installation options | Compatible 24 VAC installations |
| Detect or enable a Power Connector | A connector needs testing or is disabled | Nest Thermostat only |
| Correct the app’s C-wire record | Recorded wiring differs from the installation | Supported thermostat and app combinations |
| Recharge the internal battery | Low-battery or power symptoms | Thermostat E and Learning 3rd and 4th gen |
| Replace AAA batteries | Depleted backup batteries | Nest Thermostat only |
| Restart through the menu | Malfunctioning controls | All current models |
| Force a restart | You cannot operate the menu | Use your model’s hardware procedure |
| Power-cycle the HVAC equipment | Recurring abnormal operation | Current North American installations |
| Test through Google Home | You need to check heating or cooling | Nest Thermostat and Learning 4th gen |
| Run an on-device equipment test | You need to check the equipment response | Thermostat E and Learning 3rd gen |
| Run the on-device power test | You need to investigate power | Learning 4th gen |
| Compare with the previous thermostat | You need to isolate the cause | North American installation with a compatible previous thermostat and wiring photograph |
| Check HVAC compatibility | Wiring or equipment compatibility is uncertain | Current North American models |
| Reset for W/R reconfiguration | A wiring-help-code procedure requires it | Nest Thermostat with incorrect W/R configuration only |
| Arrange maintenance or support | Failures recur or fixes provide temporary relief | All current models |
Let the startup delay finish
Keep your temperature setting unchanged while the countdown runs. Google says some HVAC systems have a built-in delay of five minutes or more. If the countdown repeatedly starts over or the equipment never begins heating or cooling, continue with the power checks.
A display reading Starts in XX:XX and counting down from 30 minutes can be a separate Compressor heads-up diagnostic pause on compatible air-conditioning or heat-pump installations. Allow that pause to finish. If a compressor alert follows, turn the thermostat ring to dismiss it and arrange HVAC service.
Read the thermostat’s power information
On the Nest Thermostat (2020), open Settings > Equipment and record any help code. On the Nest Learning Thermostat (4th gen), open Settings > Equipment > Wiring Info and record any help code. For these models in the United States and Canada, gray wires indicate missing electrical detection; if every wire is gray, check the HVAC power supply.
On the Nest Thermostat E and Nest Learning Thermostat (3rd gen), press the ring and open Settings > Technical Info > Power. Compare the available Battery, Voc, Vin, and Iin readings with the model-specific table in Google’s Nest thermostat information menu help page. Rechargeable-battery voltage should exceed 3.6 V during normal charging; that threshold does not apply to the Nest Thermostat’s replaceable AAA batteries.
On the fourth-generation Learning Thermostat, you can also access an on-device power test. Press the thermostat toward the wall, rotate to Settings, and press to open it. Open Equipment to inspect wiring and power information and access Power Test.
Check the HVAC power and equipment cover
For a Nest Thermostat (2020) or Learning Thermostat (4th gen) with a no-power alert, check the HVAC breaker, fuse-box supply, and system switch. Restore power if it was switched off. This check also applies when an N260 code follows a Power Connector installation.
Refit the furnace or air-handler cover completely, because its safety switch may prevent operation while the cover is open. On the Learning Thermostat (4th gen), an unlit baseplate level indicates no incoming power. If power remains missing, continue with the connection checks or have an HVAC professional investigate.
Inspect the wire connections and display
Switch off HVAC power at the system switch or fuse box before handling thermostat wiring. Remove the display and inspect each wire individually. Its exposed end should be clean, straight, and between ⅓ and ½ inch long.
Re-strip damaged wire ends only if you are competent to do so. Reinsert each wire into its correct connector so the connector button stays down, then reattach the display until it clicks and restore power. These North American Nest installations require solid-core copper thermostat wiring; stranded or otherwise unsuitable wiring needs professional adaptation.
For a Learning Thermostat or Thermostat E with accompanying startup or power trouble, check that the display sits properly on its base. With HVAC power off, remove the display, gently tuck protruding wires back into the wall, and press the display onto its base until it snaps into place. Incorrect mounting screws can also prevent proper seating. Restore power after the display is attached.
Resolve a recurring C wire power problem
Recurring delays can indicate inadequate power. In compatible North American installations, switch off HVAC power before checking and reseating an existing C wire. If that wire still has no power, have an HVAC professional verify its connections at both ends.
A spare conductor must connect correctly at the HVAC equipment as well as at the thermostat. If that cannot be done, arrange a new C-wire installation or consider a Nest Power Connector. The connector supports compatible 24 VAC installations with the Nest Thermostat, Thermostat E, and Learning Thermostat (3rd and 4th gen).
Review the Nest Power Connector and installation options, and consult Google’s Nest Power Connector support page for model compatibility and its Installation Guide. Switch off HVAC power and follow that guide for your actual wiring configuration. Install the connector at the furnace or air handler for a single thermostat, or at the zone controller for a zoned system. Use an HVAC professional when the equipment or wiring is unclear.
After installation on the Nest Thermostat (2020), set the thermostat to Off, then open Settings > Equipment > Power Connector > Power test. Select Done when the test finishes, then check Settings > Equipment > Power Connector > Power Status. If the connector is disabled, open Power status and select Enable, then Continue, then Done.
Correct the app’s wiring record only when its C-wire information does not match the actual installation. In Google Home, touch and hold the thermostat tile, then open Settings > Thermostat > Wiring. For supported Nest app combinations, open Settings > Thermostat > Wiring > Update wiring. Make the record match the actual connections.
Recover a depleted thermostat battery
When a Learning Thermostat (3rd or 4th gen) or Thermostat E is charging, allow up to an hour. To accelerate recovery from low-battery or power symptoms, remove the display and connect its USB port to a powered wall charger. Google says to use a wall charger, not a computer USB port, for this procedure.
The Learning Thermostat (4th gen) uses USB-C; older rechargeable models use the appropriate mini-USB or micro-USB connection. Reattach the display when prompted. Charging restores the battery but does not repair the underlying power supply, so recurring depletion needs further power troubleshooting.
The Nest Thermostat (2020) uses replaceable AAA backup batteries. Remove its display and replace both batteries with high-quality 1.5 V AAA alkaline batteries, matching the compartment’s polarity markings. Press the display back onto the base until it clicks.
Restart malfunctioning or frozen controls
A menu restart preserves your settings and can help with a malfunctioning thermostat. On the Nest Thermostat (2020) or Learning Thermostat (4th gen), open Settings > Restart; on the Nest Thermostat (2020), choose Yes to confirm. On the Thermostat E or Learning Thermostat (3rd gen), open Settings > Reset > Restart.
Use a forced restart only when you cannot operate the menu. A forced restart may lose unsaved information. On a Learning Thermostat or Thermostat E, hold the thermostat down until the screen turns off, approximately 10 seconds, then release it and press and release the ring. For a frozen Nest Thermostat (2020), remove the display, remove and reinstall both AAA batteries, then click the display back onto its base.
Restarting does not substitute for correcting inadequate power. If restarting provides only temporary relief, have the power supply and equipment investigated.
Test whether heating or cooling starts
For the Nest Thermostat (2020) or Learning Thermostat (4th gen), open Google Home, select Favorites or Devices, choose your thermostat, then open Mode. Choose Heat or Cool. Raise the heating target until the display turns orange, or lower the cooling target until it turns blue.
Check the system’s output after about five minutes. Radiant systems can require 30 minutes or longer, and testing may be restricted in unsuitable outdoor temperatures. Check the equipment’s actual response.
On the Thermostat E or Learning Thermostat (3rd gen), open Quick View > Settings > Equipment, then select Continue and Test. Choose an available option, Heating, Cooling, or Fan, and check the equipment response. Select Continue Testing if a slow system needs more time.
For recurring abnormal operation in a North American installation, switch HVAC power off at the breaker, wait a few minutes, then restore it. If the problem temporarily disappears and returns, arrange equipment maintenance. A heat pump blowing air at the wrong temperature may need reversing-valve or O/B configuration troubleshooting.
Resolve wiring errors and recurring failures
Use a factory reset only when Google’s wiring-help-code procedure calls for W/R reconfiguration on the Nest Thermostat (2020). This is not Google’s general remedy for a Delayed message. The removal and factory-reset procedure erases the thermostat’s configuration.
In Google Home, open Favorites or Devices > Climate > your thermostat > Settings > Remove device, then select Remove. On the thermostat, tap the right side and open Settings > Factory reset, choose Reset, then select Yes. In Google Home, tap Add and repeat setup with the correct wiring information.
Have an HVAC professional investigate recurrent shutdowns, power loss, or equipment failure, especially when charging, replacing batteries, or restarting provides only temporary relief. A clogged filter can cause overheating and interrupt thermostat charging. For thermostat wiring assistance, open Google’s no-power troubleshooting page and select Contact us.
Frequently Asked Questions
Can you check Nest battery information from your phone?
In Google Home, open Favorites or Devices > Climate > your thermostat > Settings > Device information. For the Thermostat E and Learning Thermostat (3rd gen), the Nest app path is your thermostat > Settings > Technical Info. Inspect the available battery and device information, but the apps do not necessarily show every on-device power measurement.
How can you tell whether scheduling is involved?
Review operating history to distinguish scheduling from equipment trouble. In Google Home, open Favorites or Devices > Climate > your thermostat > Energy dashboard, then choose Day, Week, or Month. For the Thermostat E and Learning Thermostat (3rd gen), open your thermostat > History in the Nest app and select a day. On the thermostat itself, use Quick View > History on Learning Thermostat (3rd gen), or Settings > History on Thermostat E.
Can your previous thermostat help identify the cause?
In a North American installation, you can compare operation with a previous compatible thermostat if you have a reliable original wiring photograph. Switch off HVAC power, remove Nest, and reconnect the previous thermostat using that photograph, then restore power and test. Trouble with both thermostats suggests HVAC maintenance; normal operation with the previous thermostat suggests Nest wiring or power compatibility.
How do you check whether your HVAC system is compatible?
For a current North American Nest model, open Google’s Nest thermostat compatibility page and follow Compatibility Checker. Switch off equipment power before exposing wires, then enter the existing terminal labels rather than wire colors and omit jumper wires. Have a professional assess incompatible or complex equipment.