When your home is too hot or too cold, it’s all too easy to suspect an HVAC malfunction. But will a bad thermostat cause a heater not to work? Yes, thermostat issues are just as likely to cause heating or cooling problems and are often easier to troubleshoot and fix. Determine how to tell if home thermostat is bad with these telltale signs and troubleshooting tips.

When the Writing’s on the Wall:
How to Tell if Home Thermostat Is Bad

Even when it’s not working correctly, a thermostat can give clues that it’s malfunctioning. From a lack of power to an HVAC that doesn’t turn on, here’s how to tell if home thermostat is bad.

#1. Thermostat Has No Power

Wondering how to tell if your home thermostat is broken due to a lack of power? It will likely be unresponsive to temperature adjustments or other commands and have a dark display panel. If changing the battery doesn’t solve the problem, the thermostat may require replacement.

#2. Your Heater or AC Won’t Turn ON

While a broken AC fan or heat pump can keep a heating or cooling system from turning on, so can a thermostat problem. Usually a wiring issue within the thermostat will prevent the system from receiving the electrical signal it needs to start. When should I replace a home thermostat? If an inspection of the wires shows visible damage, the thermostat should be replaced.

#3. Room Temperature and Thermostat Setting Don’t Match

A room that feels hotter or colder than the thermostat setting is also how to tell if home thermostat is bad. While a home that’s zoned may have different temperature settings, a zone-free home should be the same temperature in each room. If some rooms in your house are warmer or cooler than others, make sure you’re using the best temperature settings. If the thermostat is set correctly and the room temperature still doesn’t match the setting, the thermostat is likely at fault. 

How to Test Your Furnace Thermostat

Wondering how to test a home thermostat to determine if it’s functioning? The following assessments can pinpoint a malfunction.

Step 1: Confirm Thermostat Settings

First, make sure your thermostat is set on “heat” during cooler months and “cool” during hot months. If either your heat or AC runs continually, make sure the thermostat is set to AUTO so that the system’s fan doesn’t run constantly.

Step 2: Adjust Temperature Settings

Raise or lower the thermostat’s temperature setting by 5 degrees. When the settings are changed, you should hear the system click on. You should also feel air blowing out the supply registers. If you don’t hear or feel these signs, the thermostat may be broken.

how to tell if your home thermostat is broken

Step 3: Check For Loose Wiring

Turn off the power to the thermostat at the circuit breaker and remove its cover. Make sure all wiring is properly attached to its screws and that all screws are secure. Tighten any loose wiring or screws before turning the thermostat’s circuit breaker back on.

Step 4: Clean the Thermostat

If you have a mechanical thermostat, dust that’s trapped under the cover can cause malfunctions. Use a small brush or cloth to gently remove any visible dust from around the thermostat’s wiring.

Step 5: Test Wiring and Connections

Wondering how to tell if home thermostat is bad if the above tips don’t solve the problem? If the wiring is properly tightened and connected, one of the wires may be faulty. A professional service should assess the thermostat to pinpoint the failed wire and determine if the thermostat requires replacement.

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