Thermostat Not Reaching Set Temperature: 7 Causes + Fixes

The thermostat setting is quite simple: Set a temperature, and AC or furnace will reach the set temperature. That’s the theory at least. In practice, we experience a problem of the thermostat not reaching the set temperature quite often.Here are just a few ways how homeowners express this temperature setting problem:“Why does my thermostat not match my home’s temperature?”Why is digital thermostat reading higher than setting?” This is primarily a problem with the AC thermostat setting (cooling).“AC not reaching the set temperature. What’s the issue here?”“Furnace is not racing the set temperature. Am I missing something?” This is primarily a problem with the furnace thermostat setting (heating).To illustrate practically what is happening, here is what many folks are experiencing in the summer and in the winter.Thermostat not reaching temperature set temperature in the summer (AC and cooling problems):Start indoor temperature is 80°F.You set an air conditioner’s thermostat to 75°F.After...