When you notice temperature inconsistencies in your home, you may struggle to find the immediate cause. Low output or efficacy in your HVAC system might result from issues with the thermostat, air filters, blower, ductwork, or other problems. To determine whether the thermostat might have faults, you can change the temperature setting and use another temperature sensor to measure the room temperature. If the numbers are noticeably different, your thermostat may not work properly.