How to Test Whether a Thermostat Is Sending a Signal

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Things You'll Need

  • Screwdriver

  • Battery

Adjust the temperature settings to check if the thermostat is sending a signal.

During cold winter months, a properly working heater becomes essential. The preferred temperature is set on the thermostat device and if the temperature in the house drops or rises beyond that setting, the thermostat will send an electrical signal to either the heater or air conditioner. When the temperature is back within range, the heater or air conditioning unit will turn off. Before hiring an outside contractor to investigate problems with your HVAC system, check to make sure the thermostat is actually sending a signal. The problem might be as simple as a faulty thermostat or bad wiring.


Step 1

Turn the thermostat setting to "Off."

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Step 2

Take off the faceplate on your thermostat unit. Remove any screws from the front casing; otherwise, check the sides for a release tab or pull the case off directly. Check with the thermostat manual for specifics to your model if you cannot figure out how to remove the faceplate.


Step 3

Replace the battery in the device. A weak battery might be able to show the basic controls on the thermostat but not be strong enough to send an electrical signal. Once the battery is replaced, put the faceplate back on the device.

Step 4

Ask a family member or friend to stand next to the heating furnace. The furnace is usually located in the attic or under a crawl space, such as the space under the house.


Step 5

Turn the thermostat setting to "Heat" and put the temperature down lower than the current temperature reading for the house. For instance, if the thermostat shows a house temperature of 70 degrees, set the thermostat to 65 degrees.

Step 6

Slowly increase the temperature setting for the heat. As you increase the temperature, the heater will produce an audible noise, most often a clicking sound. If your helper does not hear any noise, the thermostat is not sending an electrical signal.



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