Thermostat Says Heat On But No Heat – How to Solve it?

Why Thermostat Says Heat on but No Heat is prone to this problem? A thermostat plays a crucial role in a home since it controls the heating and cooling system’s decisions about what temperature to maintain there.

I attempted every fix suggested in the thermostat manual, but nothing appeared to work. I then used the remainder of the day to search the internet for solutions to the problem.

The most frequent causes of this issue include a filthy filter, a broken thermostat, a malfunctioning pilot igniter, incorrect settings, or a low battery problem. All you would need to do in this situation is clean the device, check the thermostat settings again, or change the batteries.

To fix this: Cleaning a dirty filter and the pilot igniter, changing thermostat batteries, checking the installation, making sure the sensors are operating properly, making sure no circuit breakers are tripped, and finally resetting the thermostat should resolve the problem.

Here is the Reason of Thermostat Says Heat on but No Heat

Filter Is Dirty          

  Thermostat Says Heat On But No Heat     

A clogged filter may be the most frequent cause of this problem. You would only need to glance at your filter. If the item seems unclean, the airflow is constrained and your furnace is unable to function.

A new filter should ideally be purchased every two months or so. By the way, you won’t go overboard since if the filter is unclean, it won’t be able to heat your home as efficiently, which will lead to larger expenses.

Dirty Pilot Ignitor

Another typical issue that could arise if your furnace is gas. Turn off the electricity and remove your furnace’s front panel if you’re comfortable working with various gadgets. Does the ignitor appear to be blocked and dirty? Then, it appears that you would need to contact a qualified team to address it.

The Power Source Is Cut Off To the Heater

To be sure that the electricity was not turned off, check your electrical panel. The following step might seem apparent, but make sure you check the power switch. Is the switch turned on?

Sensor not working

If the thermostat is not physically broken, it is conceivable that the sensor is malfunctioning and not delivering the proper temperature information.

The Thermostat’s sensors have a lifespan of five to 10 years, and replacing them can be rather expensive.

Weak Battery

Some residences feature battery-operated thermostats. If your analog thermostat is giving you trouble despite always functioning flawlessly, consider changing the batteries.

Even if you never see the “change bat” notice, it is still wise to routinely replace the batteries in your thermostat.

Thermostat Malfunction

Thermostat malfunction indicates too many problems.

  • The thermostat required re-calibration.
  • The settings on the thermostat are incorrect.

How to fix Thermostat Says Heat on but No Heat

Reset Your Thermostat


The first thing you do when this issue arises is to reset your thermostat, there are various brands and thermostat models, and each has its own resetting procedures. Get your thermostat manual guideline and reset them accordingly.

If the problem still persists then you need to go to the next section.

Avoid Setting Too High Temperatures

Your HVAC system may not be able to handle or deliver the temperatures you set. The most frequent reason why a Honeywell thermostat displays “heat on” even if there is no heat is this, the fix is simple.

For instance, if it’s freezing outside, you might set your thermostat to 80 degrees, but it can only go as high as 70.

Here’s how to fix the issue:

  1. Check your furnace and always be aware of its capabilities.
  2. Set up realistic temperatures for your heating system.
  3. If need be, upgrade the heating system to a bigger or more capable unit.

Cleaning A Dirty Filter and Ignitor

There should be a concern if dirt begins to build up on your furnace’s walls or fan blades.

Your HVAC system’s efficiency might be significantly reduced and fuel or energy wasted.

The HVAC furnace may have a tougher time heating your house if the filter is blocked. The filter system, blower, and motor, the furnace’s three main components, are vulnerable to clogging, especially when used regularly.

A screwdriver, clean rags, a replacement filter, a vacuum, and a toothbrush are required.

How to clean the blocked furnace components is as follows:

  1. To access the blower or to reach the front of the furnace, remove the outside panel from your furnace or air conditioner.
  2. Slide the fan unit out after unscrewing it with a screwdriver.
  3. Remove any debris from the motor casing, belts, blower assembly, and pulleys.
  4. To clean each fan blade and remove any dirt from between the blades, use your toothbrush.
  5. To avoid heat accumulation, remove any dust and debris from the motor housing’s inside and exterior.

Establish That the Furnace Is Turned On and the Cover Is Closed

Make sure the furnace is turned on before setting the thermostat to “heat.”

Additionally, make sure the furnace’s breaker is set to the ON position.

In some circumstances, if the furnace lid is open, the thermostat won’t pump heat.

Therefore, totally close the furnace door when setting the thermostat.

Tripped Circuit Breakers


Circuit breakers are built into HVAC systems to guard against overloading and damage.

Your thermostat won’t pump hot air if these circuit breakers are off.

In order to determine whether the circuit breakers are in the “OFF” position, just access the electrical panel if your thermostat won’t turn on the heat.

If so, turn it to the ON setting.

The sensors are Not Working

Your thermostat won’t adequately pump heat if the temperature sensor is broken.

Use a thermometer to measure the temperature in the room and compare it to the temperature your thermostat is showing to determine the state of your sensor.

You can presume that the sensor is broken if the temperatures are not the same. The sensor will then need to be replaced.

Incorrect Installation

When it comes to poor installation, there are two scenarios:

You installed the thermostat without a technician’s assistance (either by yourself or a handyman). In this situation, mistakes might include incorrect wiring, thermostat misalignment, etc.

Check the wire connections when opening the thermostat panel and consult the thermostat manually.

Leave it to a professional if you are unsure of what to do.

The thermostat was put in a location with airflows, such as next to a window or an air vent. The approaching wind in these areas will have an impact on the temperature measurements. As a result, your room won’t be appropriately heated or cooled by the thermostat.

This problem can be fixed by moving the thermostat to an area with a little breeze so that it can properly monitor the temperature.

Replace Worn Out Furnace System

The furnace system includes various elements that, like all household electronic systems, gradually lose efficiency over time.

Although certain parts are more effective and survive longer than others, professionals in the field recommend replacing them every ten to fifteen years.

In the majority of instances, it begins with refrigerant leaks, followed by valve leaks that can last a very long time. Even though your Honeywell Thermostat is perfectly OK, if your HVAC system is not serviced, it will undoubtedly fail to fulfill the purpose for which it was designed.

The following describes how to replace a worn-out furnace system:

  1. Verify the pressure of the HVAC refrigerant.
  2. Verify the refrigerant pressure fits the specifications by checking the HVAC system specifications.
  3. To determine the proper values for the head and tail pressures of the compressor unit, see the manual or HVAC covering.
  4. Run the compressor and check the pressures at the head and tail.
  5. If the compressor has to be replaced because the head-to-tail pressure ratio is too low.

Honeywell Thermostat Heat Not Working On Auto

If the problem with the heat turning on has been fixed but a new problem has arisen—the heat not functioning in Auto Mode—try the following. Here’s what to do if this happens to you, to help you feel less overwhelmed.

Contact Support:

If nothing works or replacement is required for a worn-out furnace system then you need to contact an expert technician or contact the HVAC or thermostat company support service center.

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