Blog

Is your room temperature lower than the thermostat setting? If so, you may have a malfunctioning thermostat. 

This common HVAC issue can disrupt comfort and signal deeper problems within your heating and cooling system. Whether you're dealing with inconsistent temperatures or your system won't stop running, understanding the root cause is crucial for maintaining home comfort. 

Let’s look at some of the possible reasons why your thermostat won’t change temperature. We’ll provide troubleshooting tips you can try out to fix these problems as well as preventative measures you can use to avoid them altogether in the future.

Signs of a Malfunctioning Thermostat

When your thermostat malfunctions, several telltale signs can identify the underlying problem:

• Temperature Inconsistencies: If you notice your room temperature is lower than the thermostat setting, your system may be short-cycling. This issue particularly affects rooms farthest from your HVAC unit, creating noticeable comfort contrasts throughout your home.
• Non-Stop Operation: An AC or furnace that doesn't shut off upon reaching the desired temperature often indicates failed thermostat wiring or calibration problems. These issues can cause your thermostat to send incorrect signals to your HVAC system, resulting in inefficient operation and increased energy costs.
• Erratic System Behavior: Unusual sounds or irregular cycling patterns from your heating and cooling system may point to thermostat communication problems that require professional attention.

Possible Causes of a Thermostat That Won’t Change the Temperature

Below are some of the most common reasons for a malfunctioning thermostat:

1. Incorrect Thermostat Settings

• Thermostat Mode Mismatch: If the thermostat is set to the wrong mode — such as using the heating mode when cooling is desired — it can seriously impair home comfort. 
• Fan Settings Impacting Temperature Regulation: The fan settings on the thermostat can also affect the overall temperature regulation in your home. For example, if the fan is set to "on" instead of "auto," the fan will run continuously, which may lead to temperature inconsistencies throughout different areas of the house.
• Incorrect Scheduling or Programming: Many modern thermostats come with programmable features that allow homeowners to set specific temperature schedules. Incorrect scheduling or misconfiguration can lead to heating or cooling at inappropriate times, resulting in higher energy bills and discomfort.

2. Thermostat Placement Issues

• Impact of Poor Placement: Poorly positioned thermostats can cause cycles of overheating or overcooling, dramatically affecting comfort levels and causing the HVAC system to work harder than necessary. Over time, this leads to excessive wear and tear.

3. Dirty or Malfunctioning Components

• Dust and Debris: Accumulation of dust and debris can impede the function of the thermostat’s sensors, leading to incorrect temperature readings and inefficient system operation. Regular cleaning and professional HVAC maintenance are essential to prevent dust accumulation.

4. HVAC System Problems

• Insufficient Refrigerant: Cooling systems require a specific amount of refrigerant to function properly. A low refrigerant level can hinder the system's ability to cool effectively, leading to warmer indoor temperatures and potential system damage.
• Aging or Damaged Components: Over time, HVAC components can age and wear down, impacting their performance. Professional HVAC inspections and maintenance are important to identify and address any aging or damaged parts before they lead to significant issues.

5. External Factors

• Weather Damage: Extreme weather conditions, such as heavy storms or intense heatwaves, can damage HVAC systems externally. Make sure that outdoor units are regularly protected and checked for damage.
• Insulation Issues: Poor home insulation can greatly affect indoor temperature regulation. Drafty areas can allow heated or cooled air to escape, leading to discomfort and elevated energy expenses. Regular checks and improved insulation can promote better energy efficiency and comfort.

Troubleshooting Steps

Step 1: Check and adjust thermostat settings

Always ensure that the thermostat is configured to the appropriate setting for the season — “heat mode” vs “cool mode” and “auto” vs “on”.

Step 2: Inspect thermostat placement

The placement of a thermostat is crucial for accurate temperature readings. If the thermostat is located near drafts from windows or doors, in direct sunlight, or close to heat-producing appliances, it may not accurately sense the ambient temperature, leading to inefficient heating or cooling. Ensure the thermostat is placed in an area where it can accurately assess ambient temperatures.

Step 3: Replace or clean filters

Dirty air filters restrict airflow, causing the HVAC system to work harder and run less efficiently. This can lead to poor temperature control and increased energy usage. Replace and clean air filters regularly as recommended by the manufacturer.

Step 4: Test batteries and wiring connections

Low or dead batteries in a battery-operated thermostat can result in complete loss of functionality. It’s important to regularly check and replace batteries to ensure proper operation. Likewise, inspect the wiring for visible damage. Frayed or disconnected wires can lead to a loss of conductivity.

Step 5: Schedule professional HVAC maintenance if necessary

If you don’t know how to perform any of these troubleshooting steps or you don’t feel comfortable doing them yourself, call an HVAC professional. Especially in situations where you risk fire or electric shock, it’s important to rely on HVAC experts who possess the right training and equipment for the job.

Preventative Measures to Avoid Future Issues

• Regularly maintain your HVAC system
• Replace air filters as recommended
• Upgrade to a programmable smart thermostat for better temperature control
• Improve home insulation

When to Call a Professional

Professional HVAC technicians are trained to diagnose and repair thermostat issues quickly. If your thermostat is not reaching the set temperature, timely intervention can help prevent costly repairs down the road. That said, it’s important to know when to call on these professionals.

Some of the scenarios in which it’s time to call a professional include:

• Complete HVAC system failure
• Issues with electrical components
• Installing new batteries doesn’t help
• Cleaning and adjusting the placement of the thermostat doesn’t fix the problem

Conclusion

Now that we understand some of the common reasons why your thermostat won’t change temperature, it’s time to reinforce the importance of scheduling regular HVAC maintenance to prevent these issues from happening in the first place. If your thermostat won’t change temperature and the troubleshooting tips outlined in this guide don’t resolve the problem, contact T.Webber for knowledgeable thermostat solutions.

At T.Webber, we specialize in thermostat maintenance and repair. We know how to quickly identify and resolve issues, saving you from the time, frustration, and risk associated with DIY repair.