The screw is located in the center of a curved piece of thin metal inside the device. Turn the screw back and forth with the help of a screwdriver till you feel that the contacts have opened. Wait for a few seconds. Then turn the calibration screw again until the contacts have closed.
Use the manual to find the screw for calibration. Turn the screw to match the temperature of the thermostat to the room temperature. Turn the HVAC system and the power back on, and the power. Turn on the thermostat and wait a few minutes for it to adjust to the temperature.
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.
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.
If the temperature is set to 74°F but the thermometer shows 78°F, you will have to recalibrate the thermostat to account for this 4-degree deviation. Even with older AC units or furnaces, you might have to recalibrate your thermostat from time to time.
A dysfunctional fan can be why your thermostat won't change temperature. This problem prevents the furnace system from forcing heated air into your home. Solution: switch off the furnace, wait two minutes, then switch off the fan.
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.
If your thermostat is set to a temperature regulation mode or has an energy-saving program enabled, it might reset to conserve energy.
Clean the Thermostat. Sometimes, when the room temperature doesn't match the thermostat setting, the problem could be dirt buildup on its interior parts. A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings.
You can usually find the ECT sensor near the thermostat in the cylinder head or thermostat housing, while a second sensor sits on a different part of the engine or radiator. A bad engine coolant temperature sensor shows symptoms like poor mileage, hard starts, an illuminated check engine light.
Checking the calibration of your thermostat is easy and should be done once a year, generally in the fall. To do so, locate your home's thermostat and tape an accurate thermometer on the wall next to it. Wait 15 minutes and check the temperature reading on both devices.
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.
Fill a large container with crushed ice, and then add clean cold tap water until container is full. Stir. Place the thermometer stem/probe into the ice water. Make sure the thermometer is not touching bottom or sides of the glass Hold the thermometer by its top for 30 seconds or until the reading stays steady.
Access the Menu: Once the thermostat is off, press and hold the center button on the device. This will bring up the main menu. Navigate to Reset Option: Use the arrow buttons to navigate to the “Settings” option, then select “Reset” from the list. Select Factory Reset: You will see a few reset options.
To reset a non-programmable digital thermostat, you'll need to take the face-off and hold the reset button for five seconds. You can also try removing the batteries for five seconds. Both of these methods should result in a reset thermostat.
First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.
The calibration screw is typically located in a curved piece of metal. First, remove the control unit from the wall mounting and then locate the screw in the back. Turning it back and forth opens the contacts. Once you feel the setting is correct, turn the calibration screw again to close the contacts.
Once you set your thermostat (the main interface between you and your HVAC system), you likely assume it's guiding your heating system to warm your home to the set temperature. It may not be. Thermostats can lose calibration over time from being accidentally bumped or from dirt accumulating.
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.