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How to Tell if Your Home Thermostat is Bad

how to test a home thermostat

When the house won’t cool down on a hot day or warm up on a cold night we often blame our HVAC system. But the problem can also begin on a much smaller scale: the thermostat. We’ll discuss how to tell if your home thermostat is bad with simple signs like a lack of power or response to your commands. We’ll also provide a step-by-step guide for how to test a home thermostat and pinpoint the problem.

Signs Your Home Thermostat is Bad

When your home central heater isn’t working or your AC won’t turn on there are usually some clear indicators something’s wrong. But the mysteries of a thermostat can leave you wondering, “When should I replace my home thermostat?” Here’s how to tell if your home thermostat is broken and not your furnace or AC:

#1. Thermostat has no power

When the display is not lit and heat and cool air are unresponsive to your commands it’s likely your thermostat has lost power. If a battery change doesn’t restore power to your thermostat, it may have malfunctioned.

#2. Your heater or AC won’t turn ON

Will a bad thermostat cause a heater not to work or an AC not to turn on? Yes, if there is a wiring problem that prevents these signals from transmitting. Your thermostat uses wires to transmit electric signals to your heating or cooling system at your command. An issue with these wires can cut off communication to your AC or furnace.

#3. Your heater or AC won’t turn OFF

Similarly, you can tell if your home thermostat is bad if your heater or AC don’t turn off at your command. This can mean that the thermostat isn’t calibrated correctly or there is a wiring malfunction.

#4. Room temperature and thermostat setting don’t match

Your thermostat may be reading a room at one temperature but it can certainly feel different to you. You can tell if your home thermostat is bad if your measurement of the room’s temperature is different than the thermostat’s reading.

How to Test Your Furnace Thermostat

Our step-by-step guide shows you how to tell if your home thermostat is bad with some simple tests.

Step 1: Reset the thermostat lower or higher

Check to see if the heat or AC turns on if you set the thermostat 5 degrees higher or lower than normal.

Step 2: Make sure the thermostat is ON

As basic as this sounds, buttons are mistakenly pushed all the time. Make sure the thermostat is on and double check that your HEAT or COOL setting is selected.

Step 3: Check the wiring

Turn the thermostat’s breaker off. Open the thermostat cover and make sure all wiring is properly attached and screws are tight.

Step 4: Turn breaker back on

Observe if the thermostat turns on and functions properly after turning the breaker back on. If the thermostat doesn’t turn on or appears faulty, retest by turning the breaker on and off again.

Step 5: Reexamine wires

Make sure the breaker is off and examine the thermostat wires one more time. Locate red and green wires to turn on the AC and red and white wires to turn on the furnace.

Step 6: Wrap wires together

Remove either the AC wires or furnace wires from their port and wrap them around each other. Turn the breaker back on. If the AC or heat turns on, it’s likely that your thermostat is what’s causing the problem.

Knowing how to tell if your home thermostat is bad can save valuable troubleshooting time getting to the bottom of heating and cooling issues. If thermostat trouble still remains a mystery, call Dependable Heating and Air for the most reliable HVAC repair in Atlanta.

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