Nest Thermostat Saya Delayed? Do This!

Why Does My Nest Thermostat Say Delayed?

Why Does My Nest Thermostat Say Delayed?

Have you installed a Nest thermostat but it has been randomly “delaying” the air conditioning for some minutes to two hours. The causes of the delay are explained here.

1. Poor battery levels

Many programmable thermostats including Nest run on batteries. Newer models have built-in batteries that cannot the changed.

These batteries provide backup power during a power outage and are not designed for long-term use

The “Delayed” message on Nest thermostats arises low battery power.

The current voltage of your Google Nest thermostat’s internal rechargeable battery will fluctuate, but it should be higher than 3.6V when it’s charging normally.

If your thermostat isn’t receiving enough power to charge the battery and it falls below 3.6V, your thermostat will turn off Wi-Fi, delay software updates, and disable the screen to preserve
the battery charge and delay shutting down completely.

Note that 3.7V is required to install a software update and 3.6V is required for the display to turn on when you approach.

If your Nest is running low on battery, it will turn off the HVAC equipment so it can add some charge to its battery.

This delay mode gives the battery a few minutes to charge especially if you don’t have a “C” wire or Nest Power Connector and the heat or A/C runs for many hours non-stop….


  1. Charge the device.
  2. Detach the display,
  3. Find the USB port,
  4. Connect using a suitable charging cord.
  5. Charge until you see a red-light flash.

It may take anywhere from half an hour to two hours.

2. Reattach to the wall.

Conduct this process as many times as you can. This is a temporary solution.


Install a C-wire

The delay happens when the battery on the Nest is low and needs to be charged. The Nest can’t charge its battery while it is sending heat calls or AC.

When you need heat / cooling the most (hottest days or coldest days), the Nest is sending heat calls all day and not charging itself – as a result the battery gets really low and the Nest delays so it can give itself time to recharge.


Connect a C wire (view on Amazon) and it will constantly keep the nest powered.

Many Smart thermostats require a C wire, or common wire, for power. If you don’t have this wire, your new thermostat might cause your heating and cooling system to have glitches.

A C that is connected to your thermostat wire doesn’t control heating or cooling functions. It provides Wi-Fi thermostats continuous power for heating (e.g. furnaces) and cooling systems (e.g. Air Conditioning systems).

Older thermostats don’t necessarily need a C-wire to function. Yet, an unused C-wire may still be included in the bundle of thermostat wires tucked away in the wall.

To check, simply turn off your system’s power and open the front plate of the thermostat to see the current wire connections.

  1. Connect Common Wire to Nest and Furnace
  2. Switch off power to Nest and furnace
  3. Find the blue Common wire
  4. Connect Common wire to furnace motherboard at “Com”
  5. Switch on power to the furnace and Nest
  6. Confirm that the C wire is detected in Nest “Equipment” setting.

The C wire is installed because resolves issues

  1. strange noises
  2. systems that are continuously on
  3. Systems that frequently turn on and off
  4. Fans that run constantly
  5. Fans that recurrently switch on and off


Install a Nest power connector (view on Amazon) on the HVAC equipment.


You can get it to run longer by charging the nest via micro-USB cable for half an hour or more and it should last for longer hours.


Get help from the Nest Pro support

3. Furnace safety problems

Why is My Nest thermostat still delaying?

Does your thermostat indicate that the C wire is connected, and it shows a good battery voltage stays and yet even after the C-wire insertion it is still delaying?

The delayed message will be pop up if a safety in the furnace is tripped.

This commonly comes up when the Nest tries to draw power to run from the furnace but can’t get enough through the H wiring.

The most common safety that gets tripped when A/C is running is the Condensate line backup float switch.

The thermal trip in the air handler can also cause the thermostat to delay when the temperature in the air box exceeds the safety trip and going off, leading to a delay.

It’s delaying because it does not want ruin your HVAC system. Also look into other furnace pressure points.

A delay can also be imposed by the furnace controller due to being switched too much.

It could also be a fault with your boiler. If your furnace triggers an override then this turns off/cut power to the thermostat. Essentially what is happening is the boiler is cutting power to the thermostat for some reason but the thermostat determines that it still needs heat.

The Nest has a built-in delay to prevent short cycling so you will see a countdown until that delay is over and it calls for heat again.


Rewire it to use a common wire

A Common 24V will likely need to be hooked up to provide consistent power.


Leave your nest alone to resolve the issue on its own.

If it doesn’t self-correct check your furnace for a slow draining or clogged condensate line.

4. The thermostat is not properly installed, tired, worn out and overworked

Is your Nest 3rd generation Thermostat Delaying?

Your thermostat may be experiencing long hours of work, cooling very hot temperatures, wear and tear, or poor installation.

Extremely hot temperatures and long running hours may affect some components leading it to go into “Delayed” mode.

If you find that your air conditioner can’t maintain house temp at the 95+ outdoor temperatures and the thermostat shuts down and says delayed often then it is trying stop the wear and tear in the components.

Ask yourself the following questions to troubleshoot what could be the problem.

How long have you had the Nest thermostat? Is it newly installed?

Was it professionally installed or DIY installation?

Have you been running the air conditioning for long periods especially in the very hot summer months?

Did your thermostat shut off due to overwork?

Does the thermometer keep saying “delayed” multiple times in very hot weather?

Have you connected to a C wire?


A C wire connection could make a really big difference to your thermostat’s operation.

Make sure the thermostat is set up appropriately

You can also replace your thermostat with a newer one

You can also give the AC a break and go swimming or sit in the shade.

5. Power Cut

What’s going on with your Nest and how do can you make it stop “delaying?”

Delayed means that Nest senses that the power is cut and then comes back it on.

The Nest thermostat delay occurs when Nest sees power or a signal cut. This is generally due to a slow condensate drain or a refrigerant issue.

The HVAC system does not have enough air flow or your condensate line is clogged and is backing up causing the float to cut power.

The Nest thermostat detects this and goes into delay mode to prevent trying to turn it back on right away and causing damage to the equipment.

Do you have a “C” wire connected?


Clean out the condensate line and check to see if that fixes it.

See whether there are adequate levels of refrigerant.

Get a HVAC technician to check your air conditioning unit refrigerant levels and condensate pipes.

6. The Nest thermostat is not very intuitive

The Nest thermostat is not very intuitive or responsive to information from the components for instance does not recognize that cooling alert does not work.

It takes a while to alert you that your refrigerant charge is low and does not work quickly to shut down the cooling and heating components.


Responsiveness and intuitiveness are a user design and interface issue that can only be rectified by the manufacturers or software developers.

7. The Nest App drains the battery very fast

Having the Nest app open in the background on your phone means that it is still sending periodic pings to the thermostat, and this drains the battery further.

The battery in the thermostat is overworked. It is running so close the edge of its capabilities that it can either connect to the app or run the system.


Close or completely shut down the Nest app on all of your devices, computer, to reduce the frequency of the Nest thermostat delaying.

When you shut everything down, the battery is able to run the system.

8. Interference with the thermostat

A “Delayed” notice may crop up if the is interference in the components of the thermostat

If you have had your HVAC system serviced and the technician is not properly trained, he may touch the wrong components or turn it on and off too many times.

If your Nest was adjusted and the HVAC system shut off then the thermostat was adjusted again and then the technician tried to turn the HVAC system back on, the Nest thermostat will go into delay mode to prevent damage to the equipment

The HVAC equipment gets power cycled or the cover is removed and the Nest senses the cut in power and puts it in delay mode.

The Nest delay is a safety to prevent the system from short cycling as not good for the HVAC system. This can happen when you turn the system off and on too quickly or play with the temperature.

If you switch an old system off and back on quickly, you’ll notice it doesn’t start right back up, even with an old thermostat. It’s a safety feature for the unit.


Try to leave the Nest thermostat alone, don’t keep switching it off and on.

Use trained professionals for HVAC maintenance

9. The “Delay’’ is a normal inbuilt safety mechanism

If you see your Nest thermostat going into delay mode you should not worry. It is a completely normal part of its operations.

The Nest thermostat delay is actually a normal operation of some older systems as they weren’t designed for a digital thermostat.

Nest support says that the Nest thermostat’s minimum on-off times are five minutes for heat pumps and air conditioning systems and three minutes for conventional heating systems (like furnaces and boilers).

The Nest thermostat uses these minimum on-off times for all temperature changes in its schedule.

Many heating and cooling systems have a built-in delay to prevent excessive wear. Since there are moving parts, turning your system on and off frequently may shorten its lifespan.

Nest thermostats also have a built-in delay, like many other thermostats. This is to help save energy and also prevent system wear, especially for systems that don’t have a automatically delay turning on.


Use the heat wire to charge the internal Nest battery.


If the delay keeps happens you need to add a C wire. Easy fix if you have an extra wire already (typically blue).


If you have a conventional furnace, you will also have a C terminal on your control board. Connect both ends and it gives your thermostat a constant 24v to charge with.


In the short term you can pull your thermostat off and charge it for an hour or so with a micro-USB charger.

10. Dirty components

You have a common wire connected but you still experience this Nest thermostat delay occasionally.

Your Nest will try to communicate to you that there is an issue with your Nest thermostat that needs to be resolved through the delay message. If you ignore it for too long the thermostat will shut down.

The likelihood in this case is that the Nest thermostat delay is caused by system issues like low refrigerant, condensate drain overflow, and even indirectly by dirty coils or air filters.

You may have a clogged air filter or coil that you are not aware of. A poorly designed, outdated or clogged air filter inhibits optimal air flow. Bad air filters will trip the thermal safety.

Without airflow, your system will overheat and start short cycling because there wasn’t enough airflow.


Be sure to check when the boiler is firing, and not between cycles. It will turn on and then stop for a bit, show the delay message and then resume.


Your Nest may not display delay message during the overheat because of the slow intuitiveness and responsiveness


Make sure you review your emails from Nest. They will alert you to short cycling episodes.


Replace your problematic air filter with a new one to resume normal air flow.

Brady Klinger-Meyers is an experienced writer and marketer with who currently writes for Robodens as well as other popular sites like MakeUseOf and Techzillo. At Robodens, he focuses on general smart home advice with his interest being accessories and gadgets. Read our Editorial Guidelines and Fact Checking process.


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