Thermostat not working correctly: causes, solution.


  1. Thermostat is misplaced
  2. The temperature sensor is out of order
  3. Thermostat is working but there is no heating
  4. Thermostat turns on but there is no heating icon on the display
  5. Honeywell thermostat not working
  6. White Rodgers thermostat not working
  7. Nest thermostat not functioning


Thermostat is misplaced


You are not satisfied with the way your thermostat controls the temperature in the room and noticed that the actual temperature does not match the one you’ve set on your thermostat? Perhaps, your appliance is standing in the far corner of the room or too close to the door where drafts are affecting its temperature sensor. Likewise, your thermostat can wrongly interpret temperature information if you place it too close to a radiator or under direct sunlight. The solution is quite simple: you need to take it to a place where its temperature sensor will have no temperature impact.


The temperature sensor is out of order

If you want to make sure that the temperature sensor works fine, you need to disconnect the device from the power supply, dismantle the thermostat, disconnect the wires of the temperature sensor connected to the corresponding terminals on the rear panel. Terminals are marked by the word “sensor” and can be located separately from the main terminal unit. After disconnecting the sensor, you can check its resistance. The resistance of different temperature sensors may vary and is usually in the range of 5-15 KΩ (Kiloohms).

If the resistance of the sensor is within its normal values than poor contact in the terminals might be the reason why thermostat not working correctly. You can once again carefully connect the sensor wires to the appropriate terminals. The thermostat should start working.

If the sensor resistance differs from the normal value by more than 20% – the temperature sensor must be replaced.


Thermostat is working but there is no heating

In this case, it is most likely there was a break of the heating core of the cable to the heating source.

The break can diagnosed be as follows: disconnect the wires leading to the heating system from de-energized thermostat and measure the electrical resistance between them. If the resistance tends to infinity and / or shows Mega-Ohm values, then unfortunately, the heating core has broken.


Thermostat turns on but there is no heating icon on the display

In this case, you need to set a higher temperature by rotating the knob of the thermostat or by setting the temperature on the display that would be higher than the current temperature in the room. If, in this case, the thermostat does not send a signal to heat the room, it is likely that the thermostat needs to be replaced.


Honeywell thermostat not working

Troubleshoot Your Analog Thermostat

There are several models of analog thermostats, and they differ in shape: they can have a square or round form. Most of them can be set to COOL, HEAT or OFF modes. The fan has two positions: AUTO and OFF.

  1. Switch on the COOL mode at the thermostat’s top and the AUTO mode using the fan switch. Set the lowest temperature (60 degrees F) using the temp switch or dial. Make sure that cool air begins to come in. If you hear it kick in, it is ok.
  2. If you are testing the unit for heat, switch on the HEAT mode. Set the highest temperature (e. g. 80 degrees F). Wait a few minutes to ensure that the furnace has activated. If you hear it kick in or feel that warm air is coming in, it is ok.
  3. If neither the AC nor heater kicks in, check the colored wires under the cover and make sure they are not loose or damaged. Use the color-coded diagram in the user guide. Most likely, you need to fix the low-voltage wire connections to get the unit to work again.
  4. If there are no problems with the wiring, there has to be a more serious issue, or your unit has reached the end of its service life. Install an advanced programmable thermostat.

Troubleshoot Your Digital Programmable Thermostat

There are several models and types of digital programmable thermostats featuring keypads or touch screens. Also, there are ones featuring a function enabling you to control them from a PC or mobile device (smart phone, tablet, etc.)

There are several common issues, which occur in these digital units, as well as solutions to them.

Most users face an issue when they see no indication on the digital display. The most common causes of it are:

  • The unit’s door is not closed properly. Advanced units feature digital door latches, which won’t let the entire system work unless the door is closed. When the door is shut, the latch takes a position to close the circuit and provide power supply for the rest of the thermostat.
  • If your thermostat is equipped with batteries, check them: not unlikely, they are dead. Check the battery alert, if your unit has it. If the batteries are bad, there will be a message indicating it. Replace the batteries, if necessary.
  • If your home has a dedicated circuit for your thermostat or AC (as it may be required by your building code), check the circuit breaker: it could have gotten tripped. If it has, flip it to the OFF, and then back to the ON position.

Operation Failures

If your thermostat is not controlling temperature as is should be, and the display is functional, check it for the following issues:

  • Low-voltage wire connections are loose or not positioned correctly. They should connect the heating unit to other components. If not, the unit will not work. There can be a different number of hookups depending on the unit’s model and number of components featured in it. Check the color-coded chart in the user’s manual and see if any of the wires need to be reconnected or reinstalled.
  • In programmable thermostats, improper time and day setting can cause breakdowns. Not unlikely, the time-of-day and day-of-week clock is not set properly. Usually, it gets off the track due to power shutouts. Although the battery should keep the clock functioning correctly in case of power loss, oftentimes it does not. Please, check the clock and make sure the time and day are set correctly. Check with the user’s guide and see how the clock should be set with your model.
  • Remove the cover and check the jumper settings. Your model may require that you adjust it to a particular type of AC, heat pump or furnace. There are Honeywell thermostats with the jumper needing to be in the HE setting for electric furnaces and in HG for oil or gas furnaces. Please, see what type of those you have. Once the jumper is set properly, the fan will start in an automatic mode.

Faulty Furnace or Air Conditioner

It should be noted that the problem is not necessarily in the thermostat. It is advisable to check the AC, furnace, humidifier, or any other piece of equipment installed in your home. To check that, please, do the following:

  1. Be sure that your thermostat is in the COOL mode: press SYSTEM and set the temperature to the lowest position; be sure that the fan is set to the AUTO mode. Wait for several minutes until the unit switches on.
  2. Do the same thing for heat and be sure that the fan set to AUTO. Press SYSTEM and hold it until HEAT appears on the display. Set the highest temperature. Wait for several minutes until the unit switches on.
  3. If none of these works and neither the furnace, nor heat pump, nor AC comes on, the problem is in another part of your HVAC system. It is definitely so if you are using a brand new thermostat with a fully functional and correct wiring.


White Rodgers thermostat not working

Common Issues

  • Ensure that your house/office is getting electricity and there are no power outages in your area. Check your HVAC system. If nothing is working, check the fuses and circuit breakers.
  • Be sure that your thermostat is currently in the HEAT mode. It should heat up a little and produce a clicking sound when the system starts. If it does not, check the batteries. Most likely, they are dead.
  • Before removing the batteries, disconnect the wires at the R and C terminals. Check with the White Rogers troubleshooting department to avoid confusion and remove/replace batteries properly.
  • Set your thermostat to the COOL mode. Lower the temperature by a few degrees and wait until you hear a click. If there is no click, most likely, you need to replace the batteries.
  • The problem could have been caused by a short circuit. Check the wiring for burns and make sure there are no bare ones. If there are, take steps to isolate them. Contact the White Rogers and apply for professional help: dealing with this kind of issue requires a bit of skill and experience.

Troubleshoot the Furnace

  • Check the furnace’s filter: most likely, there is dust on it, which is blocking the flow of the air. This problem must be treated immediately to eliminate the carbon monoxide hazard.
  • Use every chance to check the inside of the thermostat. For example, when replacing batteries, you can also clean it from dust and debris.
  • Make sure that the furnace’s switch is in the ON position; not unlikely, the furnace was switched off accidentally. Be sure that the breaker box is on. Try switching it on and off several times and see if it works. If it does not, contact White Rogers.
  • Check the flame in the furnace: it should be blue. If it is not, the furnace is not ventilated well. Call the White Rogers troubleshooting department.
  • There is a problem with the gas valve or the pilot light. If there is no flame, try to ignite it again. Check the owner’s manual and follow the procedure as described in it.
  • Make sure that the front panel is set correctly. The furnace may stop working if it is not.
  • Check the supply and return grills in the vents are not blocked. Make sure they are not obstructed by furniture or items stored on top of it.

Emerson Electric produces White Rogers thermostats and offers valuable help in troubleshooting, maintenance, adjustment and programming. There is a comprehensive manual for all White Rogers thermostats available all the time. You can choose to refer to Facebook and other popular networks, where the company has posted tons of FAQ stuff and attracted a good-sized community of users. There you can get answers to all questions concerning your thermostat and related HVAC components.


Nest thermostat not functioning

If your area is out of power, your thermostat will switch to the energy saving mode with wi-fi and the screen not working. This mode should help prolong the battery’s life.

Before troubleshooting, please, note the following:

  • Nest thermostats turn on automatically once there is power again and when they are connected to systems.
  • A blinking red light in the upper part of the display means that the battery is not fully charged. Please, wait until it is charged before using the thermostat.
  • As you use your thermostat, its screen may go down after a period of inactivity. However, it should turn on once it senses someone being close to it or once it is activated through an app.
  • Batteries are charged by the voltage, which your Nest thermostat gets through the system’s wires. In case of an unexpected blackout, the battery will keep the device working for a little while. However, it will switch to the energy saving mode with most advanced features turned off.
  • If there is a fault code or a wiring report on the screen or in the app, check the error code list.

Do not be in a hurry to troubleshoot. Do so only if your thermostat does not respond to your pressing on the screen or turning the ring.

Red light blinking

If you see a red light blinking in the upper part of the display, the battery is low and being charged. Please, note that troubleshooting depends on the situation, in which you see the red light flashing.

Green light blinking

If you see a green light blinking in the upper part of the display, your thermostat is starting, restarting, or the software is being updated. This lasts a minute or so. When it is over, the thermostat will start automatically. If it continues for longer, please, do the following:

  • Remove the display by gently pulling it off its base. Check the pin connector to ensure it is not damaged and all pins are straight and lined-up. Place it back into the base until it sits firmly.
  • If this does not work, push on the thermostat’s display and hold it for 10 seconds or so. Release it and wait until the unit restarts.

No indication on display

If there are no lights blinking on your thermostat’s display and the buttons are not responding, the battery is low, and the system needs more power.

Check the connection between the display and the base

If the connection is poor, the thermostat won’t start, and the battery will remain uncharged.

  • Disconnect the display and gently pull it straight off.
  • Be sure that there are no cables sticking from the base and not letting the display sit properly. If you see any, press on them.
  • To reconnect the display to the base, press straight down on it until it clicks and sits firmly.
  • If the blinking red light appears, the battery has started charging, and the unit will start working once it has fully charged. If the battery is very low, you may need to wait for about an hour.

Check the system several times to ensure it is getting power

  • Turn the circuit breaker on and off several times. Be sure that the switch goes all the way to the On position.
  • If there is a fuse box, make sure that the fuse is functional. If it is blown, replace it.
  • If there is a blinking red light, the battery has started charging, and the unit will start after a little while. If the battery is very low, you may need to wait for about an hour.

Take compatibility seriously

Please, double-check your systems for compatibility! If you try to connect your Nest thermostat to a system, which is not compatible with it (a millivolt, proprietary or high voltage system), the unit either will not get enough power to charge the battery, or it will get too much of it and receive damage

Check the wiring

  • Be sure that all wires are connected well. Prior to checking, cut off power to avoid electrocution or damage to the system and/or thermostat.
  • To remove the wire, push on the wire connector button. Check the wire.
  • Once all the wires are inspected and reconnected, fix the display on the base and plug the unit back in.

Blown fuse

If the fuse is blown, most likely, there’s been a power surge, which would otherwise damage your thermostat.

Check your Nest thermostat for damage

Damage could result from connecting the unit to an incompatible system, due to a power surge, or a short circuit. Please, use every little opportunity to check the wiring and isolate exposed wires, if any. Turn off the unit before doing any work on it.