A common oversight for a thermostat showing the wrong temperature is the state of its batteries. Dead or low-power batteries can lead to inaccurate readings. Simply replacing the batteries might restore your thermostat's accuracy and functionality.
Dirty or worn flame sensors, blower motor problems, clogs in the condensate lines, and electrical issues are some of the many problems that can leave your HVAC system failing to deliver the temperatures you've programmed in your thermostat.
That usually means that the thermostat sensor is faulty. You have two options. Change the thermostat, or simply ask for a higher temperature. So press the up arrow a few times to change the 74 to 78 and you should feel warmer.
Using an appropriately sized screwdriver, turn the calibration screw to open the contacts. Wait a few seconds, then turn the screw to close the contacts. This will reset the contacts and make sure a bad connection wasn't causing your thermostat to become uncalibrated.
Some of the most common thermostat issues include:
The thermostat is broken, not properly level, or dusty. The thermostat needs to be recalibrated. There is loose wiring causing a thermostat issue.
If your thermostat is not reading correctly, it might be due to a dirty or faulty sensor. A quick fix could be to gently clean the sensor with canned air to remove any dust buildup. However, if problems persist, replacing the thermostat could be the next step.
Clean your Air Filters, Vents, and Ducts – A clogged air filter will struggle to meet the thermostat's set temperature since the dirt and debris buildup prevents air from circulating through the vents. And as airflow into living spaces drops, so do comfort levels.
The Thermostat Has No Power
An unresponsive display is a sure sign of thermostat failure. A blank screen indicates dead batteries, a tripped safety switch or a major malfunction in the thermostat's components.
Inconsistent home temperatures and high energy bills are telltale signs your thermostat may need calibration. Thermostat calibration, as well as boiler maintenance, are essential components of HVAC systems. Properly calibrating your thermostat ensures more precise temperature control and energy efficiency.
If your thermostat is not reading correctly, it might be due to a dirty or faulty sensor. A quick fix could be to gently clean the sensor with canned air to remove any dust buildup. However, if problems persist, replacing the thermostat could be the next step.
For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.
One possible reason your AC is not reaching the set temperature is that the thermostat could be dirty. If dirt, dust, or other debris has accumulated within the thermostat box, it can cause the wires to heat up or other issues. Thermostats are cleaned during routine HVAC maintenance to help prevent this from happening.
Check the insulation in the walls and ceiling of the affected room. Adding extra insulation or caulking gaps around windows and doors can help improve insulation. Leaky Ductwork: If your HVAC ductwork has leaks, it can lead to inconsistent room temperatures. Inspect your ducts for cracks, gaps, or holes.
The Room Temperature and Setting Don't Match
If, no matter how often you set the thermostat, the setting and room temperature never match, the unit has likely lost accuracy. The cause may be a calibration issue. Or, the unit may have a wiring problem affecting its function and power supply.
If you're cold even though your thermostat indicates you shouldn't be, your furnace likely isn't the problem. In most cases, it's working just fine. It's your home that needs attention. Lack of insulation, severe air leakage, and/or unbalanced ductwork are frequently to blame.
One of the most common reasons that your thermostat is incorrectly reading your home's temperature is that the temperature sensor is malfunctioning or has failed completely. Replacing a temperature sensor can be very difficult, so there are a few things you should try before you schedule a replacement.
Locating the Reset Button
Remove the thermostat cover by either snapping it off or unscrewing it, depending on the model. Most modern thermostats will have a clearly marked reset button inside the panel. It's usually small and recessed, so you might need a pointed object like a paperclip to press it.
Standard thermostats: Enlist a friend or family member to assist, Position one person by the thermostat and one person by the furnace. Slowly turn the thermostat from off to heat and increase the temperature. Both the thermostat and furnace should make a sound.
First, replace the batteries in your thermostat as this is the easiest fix. Then, you should check that your thermostat is level and that all parts of your HVAC system are clean. In particular, look out for dirty air filters, which can be the cause of your thermostat reading the wrong temperature.
The Problem: Your air vents play a big role in keeping your home comfortable. So, if one room is always warmer than the rest of your home, the return air vents in the room could be blocked or damaged.
Your AC might not cool properly due to thermostat issues, an undersized unit, or extremely high outdoor temps—so check those first. Keep an eye on airflow—replace clogged filters every 3 months, and make sure vents and ducts aren't blocked for efficient cooling.