Heating & Cooling

Troubleshooting Honeywell Thermostats: Why It’s Not Working

honeywell thermostat lg 1

Owners of Honeywell thermostats will know that these home thermostat systems are some of the best on the market. These systems effectively cool and heat a home, but what if something goes wrong with the system? You may be asking, why is my Honeywell thermostat not working?

From faulty or incorrect wiring, a broken fan, inaccurate calibration, a tripped circuit breaker, or a full drain pan, many things might cause a Honeywell thermostat to stop working. The source of the problem and how to remedy it will be revealed by troubleshooting the thermostat.

Honeywell thermostat systems are widely used, and they do experience their fair share of problems from time to time. Let’s examine some of the more commonly encountered Honeywell thermostat problems, how to identify them, and how to resolve them.

Why Would A Thermostat Stop Working?

If the house’s electrical system powers the thermostat, check the circuit breakers first. One of these may have tripped and turned off the thermostat’s power. Reset the circuit breaker. If this doesn’t work, the thermostat’s problem could be loose connections or other wiring issues.

Honeywell thermostats are reliable, effective, and have an extensive range of Honeywell thermostat systems to choose from to suit the needs of every home. 

These systems are not immune to problems. Owners of these thermostat systems have experienced some commonly experienced issues.

Let’s have a closer look at some of the problems that may arise with a Honeywell thermostat, regardless of the model:

Thermostat Not Heating Up

One of the most commonly experienced problems users experience with Honeywell thermostats is a lack of heat or insufficient heat to heat the entire home effectively.

If a thermostat is not heating a home correctly, it can make cold days and colder nights unbearable. This means that a thermostat that is not heating up is one of the most severe problems that could occur.

It is essential to quickly determine the cause of this problem to get it fixed as soon as possible.

Thermostat Cooling Not Working

Along with a non-functioning heater, another of the most commonly experienced issues is a Honeywell thermostat not cooling down or sufficiently cooling the entire house.

Several factors could cause this, but it is a very frustrating problem to have. A thermostat that does not cool the house is pointless. Unfortunately, this could be one of the most costly problems to resolve, depending on what has caused the issue.

This could also be an issue if the thermostat heating is not turning off. If the heating function is not deactivating, the cooling function will not work.

Before making assumptions as to why the thermostat is not cooling down properly, it is crucial to correctly identify the source of the problem to be resolved correctly.

Thermostat Fan Not Functioning

One of the essential components of a Honeywell home thermostat system is the fan. The fan is responsible for properly distributing the warm or cool air generated by the system throughout the entire home.

Without a functioning fan, a thermostat is very ineffective at both cooling and heating a home. A non-functioning fan is one of the more commonly experienced problems with any home thermostat system.

It is crucial to resolve this issue fast, as it could lead to more serious problems if the thermostat system is left running without a properly functioning fan.

Display Not Coming On

The most frequently experienced issue with Honeywell thermostats is a display or screen that does not turn on.

Without a functioning display, it is impossible to control the thermostat or change any of its settings. In most cases, the thermostat can not be turned on if the display screen is not working.

A non-functioning display screen is the most common problem encountered by Honeywell thermostat owners. It is also the problem with the possible causes.

To rectify this problem, it is essential to quickly identify which possible cause prevents the display from turning on and fix it so that the thermostat system is operational again as soon as possible.

How Do I Fix My Honeywell Thermostat?

To accurately identify the direct source of the problem, troubleshooting will have to take place before the problem can be solved and the thermostat returned to proper functionality.

Multiple root issues may cause each of these commonly experienced Honeywell thermostat problems. 

Let’s go over how to troubleshoot each of these significant thermostat problems to identify the cause of the issue correctly:

Troubleshooting Heating Problems

If your thermostat is not heating up as it should, the first step is to put your hand over the vent to determine whether or not there is any warm air coming from the vents.

If you feel nothing coming through the vent whatsoever, the problem may be with the fan rather than the heating system of the thermostat.

If the fan is not functioning, perform troubleshooting of the fan rather than the heating function of the thermostat system.

If air comes from the thermostat vent but does not get warm, the issue lies with the heating system.

The most common reason for the lack of heat coming from the thermostat system is a tripped circuit breaker switch. When the heat is not working, the first thing to try is to locate the breaker board in the home and check if the circuit breaker switch for the heating system has tripped.

If the switch is still up and has not tripped, there may be a more serious problem to rectify.

Another cause for this problem may be because the thermostat system is not calibrated correctly. If the thermostat is not calibrated correctly, it will not accurately sense the home’s temperature and, therefore, will not heat the house perfectly.

This can be identified by the temperature display on the thermostat control panel. If the room temperature displayed is higher than it should be, the thermostat should be recalibrated.

Incorrect wiring may also cause this problem, especially if there is cool air coming from the vents rather than warm air. This is most likely caused by wires within the system not being connected to their proper terminals.

The wiring may also be faulty, loose, or broken, which will also cause the system not to work correctly. If you suspect that the wiring is to blame, open up the face panel of the control unit to check the wiring.

If none of these issues is why the thermostat is not heating up, it is time to check the furnace unit itself. This may require the help of a certified thermostat technician to rectify.

If you have checked every area of the thermostat system that you can check on your own, consider the weather. If the temperature outside the house is too cold, the thermostat system may not be powerful enough to heat the home.

Troubleshooting Cooling Problems

Very similar issues often cause cooling problems in Honeywell thermostat systems as heating problems. After all, the same unit is responsible for both heating and cooling the home.

Poor, damaged, or incorrect wiring is a prevalent reason why a thermostat may not be cooling the house as well as it should.

The same problem may be experienced if the circuit breaker for the thermostat system has tripped.

If the fan is not running well, the system will not effectively cool the house down, and this is the fault of the fan rather than the cooling system within the thermostat.

A poorly calibrated thermostat can also be the source of this issue, as it lacks heating. Without proper calibration, the system will not correctly sense the home’s internal temperature, resulting in an inability to cool the house to the desired temperature properly.

Suppose none of these sources have caused the problem, and the weather is not too hot outside for the thermostat to cool the home effectively. In that case, the problem may be with the air conditioning unit, in which case it may be more complicated to rectify than a DIY solution.

Troubleshooting Fan Problems

A problem with a thermostat fan is straightforward to identify. If there is no air being blown through the thermostat vents into the home, whether warm or cool, the fan in the system is not functioning correctly.

There are many causes, but the first place to check is the wiring within the control panel of the thermostat.

  • If the wiring has been damaged or incorrectly installed, the fan will not function well, or it will not function at all.
  • If wiring is not to blame, the fan itself may have malfunctioned or be clogged or excessively dirty.
  • Locate the fan in the system to identify if these may be the source of the non-functioning fan.

If none of these supply a reason why the fan is not functioning, contact a professional to help perform diagnostics.

Troubleshooting Non-Functioning Thermostat Display

The most commonly experienced problem with a Honeywell thermostat system is a display that is not turning on. 

Fortunately, there are many reasons for this issue, and they are relatively simple to resolve.

This problem is easy to identify because the screen or the display on the thermostat control panel is not on and does not come on when you attempt to power on the system.

The first check to make to determine is if the electricity to the home is on. If there is no power, the thermostat will not function.

If there is electricity, then the control panel may not be turning on because of a more significant problem within the thermostat system. The control panel may require a battery change.

Most thermostat control panels, especially those that are not top of the range, require a pair of batteries to function. This is the most common cause for the screen not to turn on.

If the batteries are fresh, it is time to investigate other possible reasons why the screen may not turn on.

The display may not come on if the system has automatically cut off due to a blockage or a sensor in the system recognizing an overflow or collection of water.

Most thermostat systems either have a drain line that removes moisture from the home or a drain pan to collect the moisture that the system expels.

If the drain line has a blockage or the drain pan is full, the automatic cut-off switch in the system will activate and not allow the system to turn on.

If none of these causes are the root of the issue, the control panel itself may be faulty or malfunctioning.

How To Fix These Common Problems

We will be sharing tips on fixing a tripped circuit breaker, improper calibration, incorrect wiring, and more. Once you have completed troubleshooting the problem you are experiencing and accurately identified the true source of the issue, it is now time to begin working on a solution.

Here are some potential fixes for the common Honeywell thermostat problems: 

Resolving problems that result in a lack of heating from the thermostat depends on the issue at hand.

Tripped Circuit Breaker

If the circuit breaker that controls power to the heating system of the thermostat has tripped, locate the switchboard, identify the switch that controls the thermostat, reset it by pushing it down completely, and quickly flip the switch all the way back up.

Improper Calibration

If you have identified that the thermostat is not calibrated correctly, this is a simple fix. All you will need is the instruction manual for the thermostat system. Look up the calibration process for your particular system in its manual, and follow the steps to recalibrate the system. This should resolve the issue quickly and easily.

Incorrect Wiring

If you have opened the control panel and found the wiring incorrect, reconnect the wires to their proper terminals. A standard guide for this is that the signal wires in the panel should be ordered white, yellow, green from left to right.

Faulty, Loose, Or Damaged Wiring

If you have discovered any of these issues with the wiring in the thermostat system, it is safest to contact a thermostat technician to make the proper repairs to the system.

Malfunctioning Thermostat Unit

If the outdoor thermostat unit has malfunctioned, it is beyond the realm of typical DIY repairs. It is best to contact an appropriate technician to perform proper diagnostics and repairs in the outdoor unit.

Dirty Or Clogged Fan

If you have found the problem to be caused by a dirty fan, clean the fan blades, hub, bearing, and motor from any debris or grime that may be present. Liberally apply a lubricant such as WD-40 to the fan base, the bearings, and the hub to ensure that the rotor can move freely, resolving the problem.

If cleaning the fan does not help, then a replacement fan may resolve the issue permanently.

Flat Control Panel Batteries

This problem has a straightforward solution. Replace the batteries in the control unit to revive the thermostat display.

Empty Drain Line And Drain Pan

Thermostat units have automatic cut-off switches in case there is too much water in the system. To rectify this, drain the fluid from the drain pan, and use a shop vac to expel the water or any blockages from the drain line. This will allow the sensor to reset and turn the thermostat back on. 


The common problems experienced by Honeywell thermostat owners are usually a lack of heat, the thermostat not cooling the home down, a non-functioning fan, or a display that will not turn on even if there is electricity running to the thermostat.

These problems can all be easily identified by performing the simple troubleshooting steps above. If none of these steps yield any solutions to the issues, contact a professional to help perform diagnostics and make the appropriate repairs.


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.