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If your HVAC system isn't performing the way you want, there might be an issue with your thermostat. Check out our list of common problems along with quick fixes to resolve the problem of your thermostat not working!

1. No Power

Firstly, check whether the thermostat display is on or not. If not, then the thermostat cannot communicate with your HVAC system. There can be several reasons why your thermostat isn’t getting power. It can be because of worn-out batteries, a blown fuse, a tripped breaker, or maybe the thermostat wiring doesn't fit tightly. 

If the batteries go dead, then you can simply replace them with new ones. The case is the same with a blown-up fuse; just change it. If the wiring is loose, you can tighten the wires and screws appropriately. For a tripped breaker, check the circuit breaker and reset.

Totaline Thermostat

2. Wrong Settings on the Thermostat

If you want to make sure your thermostat works accurately, you should learn how to program it. Consider checking the manual and programming the thermostat according to your preference. 

If the HVAC system isn’t cooling or heating as required, check the thermostat settings for the “Heat” and “Cool” options. Make sure that the switches in the circuit breaker for cooling and heating units are “ON.”

Moreover, keep the thermostat’s fan setting to “Auto” so that it only blows air when the furnace heats or cools the air. Also, ensure that the set temperature is within the range of 40° to 99° F. 

3. Corroded/Frayed Wiring

Poor wiring conditions can be a possible reason why your thermostat isn’t working correctly. A wire gets damaged if it is not correctly stripped off its insulation. To avoid this, use wire strippers that are specific for this purpose. 

The wires can corrode with time. In such a situation, the thermostat is unable to communicate with your HVAC system. It is recommended to change the corroded wires with new ones. 

In case the wires are loose, screw them tightly. It ensures a good connection between the thermostat and the HVAC system. For smart thermostats, make sure they are connected via C-wire. 

4. Low Battery or Battery Voltage Issue

Low battery problems can also affect the regular operation of your thermostat. Smart thermostats use a C-wire that connects the thermostat with an HVAC system and charges the thermostat’s battery. 

The thermostat uses battery power when the HVAC system is not running. Sometimes the thermostat faces low battery issues, or the battery is unable to charge. 

To handle this situation, ensure the thermostat is mounted correctly, and the connectors are lined up so that the power can easily flow. Some smart thermostats can also be charged via a USB cable as a quick fix.

Nest battery voltage

5. Change Thermostat Battery

The thermostat battery needs to be changed once a year. When the battery is low, the thermostat displays a “Low battery” warning. If this happens, you have to replace the old batteries.

Some thermostats use AA batteries, while some require AAA batteries. You can refer to the thermostat’s manual for figuring out the suitable battery for your thermostat.

You can change the batteries by removing the sliding compartment. Insert the batteries carefully, matching the battery polarity symbols. 

In case your thermostat doesn’t have a sliding compartment, remove the faceplate and take off the thermostat from the wall. Now you can change the batteries quickly. 

6. Reset Thermostat

Sometimes your thermostat may not work as desired. Such a situation can happen because of the inefficiency in following the programmed schedule. If this is the case, you need to reset your thermostat and program it again for better results. 

Other cases where you need to reset your thermostat include a change in the Wi-Fi network or some power failure. To reset the thermostat, you need to know the model number.

In case your Honeywell thermostat is not working, you can reset the device and configure it as required. Simply go to the menu and select “Factory reset.” After that, you can reset the Wi-Fi settings, programmed schedules, and HomeKit settings of your Honeywell thermostat.

7. Badly Positioned Thermostat

You may be surprised to know that your thermostat’s location has much to do with your thermostat’s efficiency. You should avoid placing the thermostat on walls where the temperature is not stable. 

For example, if you place the thermostat near a window or a door, it is affected by external temperature changes. Similarly, mounting the thermostat in a kitchen or near some heat emitting device may not be the right decision.

The best mounting location for a thermostat is somewhere in the middle of the house, where it can take accurate temperature readings.

8. Ensure Furnace Door Is Closed Securely

If your thermostat displays a blank screen, it may be pointing towards an open furnace door. There is a safety switch on the furnace door that pops out if the door is not closed correctly. It will stop the furnace operation.

In this situation, you need to fix the door in its position for the furnace’s normal operation. For this, switch off the power and wire a new safety switch on the furnace door. Make sure the switch closes the furnace door tightly. Now you can check whether your thermostat is working or not. 

9. Change Air Filters in Your Air Handler

Another reason for the thermostat not working may be a clogged air filter inside the furnace. In such a situation, when you turn on heating mode, there will be no warm air coming out of the blower. 

This is the time when you need to change the air filters. Take out the filter from the furnace and examine it. You can easily find out whether the air filter is clogged with dust and dirt. Now install a new filter according to the manual’s instructions. 

Generally, you should check the air filters once a month and change them after three months, depending on your area’s dust conditions.

10. Snapped Belt or Broken Blower Within Your Furnace

If your furnace is making squeaking and rumbling sounds, then this is an alarming situation. It indicates something is wrong with the furnace blower or the belt. Also, there can be an issue with the fire burner.

Your furnace will appear to be working fine, but these sounds indicate that you need an expert to examine the problem. A general solution is to oil the blower for smooth operation. You can also change a snapped belt with a new one. 

11. Dirty Mechanical Thermostat

Dust and dirt can also affect the thermostat’s efficiency. Dirt can accumulate inside the thermostat, affecting its ability to sense temperature changes. 

This is a particularly common issue if your old mechanical Honeywell thermostat is not working.

You can easily clean the inside of your thermostat by following the steps below:

  • Take off the front panel of the thermostat and clean the inside area with a brush. Gently move the brush to remove dust from the contact points.
  • If you do not want to get physical with wiring stuff, you can use a can of compressed air to remove the grime and dust inside the thermostat. 

12. Short Cycling

Short cycling refers to frequent or unusual turning on and off of the HVAC system. You can encounter this situation due to several reasons. A few reasons are mentioned below:

  • A dirty air filter can cause the furnace to short cycle. 
  • An old mechanical thermostat can also cause the HVAC system to short cycle. In this case, you have to upgrade to a new digital thermostat. 
  • Dirty vents can also cause short cycling. It is advisable to clean the ducts regularly. 
  • Other issues may include overheating, circuit board issues, dirty flame rods, etc. 

13. Turn the Thermostat Up or Down 5 Degrees to Test

There is another technique to troubleshoot a less efficient thermostat. You can try this trick and find out whether it works for you or not. 

  • You can set the thermostat five degrees higher than the required one in the winter season. 
  • You can try five degrees less than the desired temperature in the summer. 

After turning the thermostat five degrees up or down, wait to see if your HVAC system turns on and achieves the set temperature.

Thermostat Not Working? The Verdict

So there you have it! The 13 most common thermostat issues and solutions – hopefully they are helpful! In case none of the above troubleshooting ideas work, then leave a comment below!


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