What to Do if No Power is Coming to the Thermostat

An air conditioner provides cool air. A furnace or heat pump keeps you warm and cozy. But it’s the thermostat that’s responsible for ensuring your comfort. Your home will quickly become unpleasant if it’s not working. One of the most common reasons for this is the unit isn’t receiving power. Below, we’ll explain what to do if there’s no power coming to your thermostat (many of these issues are easy to fix).

Check Whether the Thermostat Is On

If someone accidentally turns the thermostat off, your HVAC system won’t receive any signals to run. It’s not infeasible to brush against something and push a switch. If your thermostat has a touchscreen, it’s even easier to make a mistake. Take steps to turn the unit on and see if it lights up and your heating or cooling system kicks in.

Change the Battery

If you have a battery-operated thermostat and haven’t changed the batteries in a while, there’s no immediate cause for panic if it stops working. The controls and the display won’t have power if the battery is drained. Changing the batteries is simple. Remove the cover and refer to the user manual and symbols in the battery casing to properly insert the batteries.

Clean the Thermostat

Another simple reason no power is coming to the thermostat is it’s dirty. Dirt, dust, and virtually any other buildup can prevent it from working. Wipe down the outside of the unit regularly. To clean the inside, remove the outer cover and either wipe down the interior with a rag or use a can of compressed air. Reinstall the cover and see if the thermostat has power.

Check the Power Supply

You’ll have to look further if the problem still isn’t resolved. There should be something on the display, even if the thermostat is off. If the screen is blank, then the device isn’t receiving power. In this case, you’ll want to check for the following:

Tripped Circuit Breaker: The main issue here is not with the thermostat itself but with the electrical panel. Go to the breaker panel and locate the circuit breaker for your thermostat. If it’s off, try to reset the breaker switch. This will often fix the problem unless the circuit is overloaded, which will cause the breaker to trip again. You may then need to unplug some devices or have an electrician inspect the wiring, make repairs, or upgrade your electrical panel.
Tripped Safety Switch: The AC safety switch may trip due to excess moisture or a mechanical or electrical issue. This is the next place to look if resetting the circuit breaker doesn’t work or if the breaker is fine. When the safety switch turns off, the transformer will stop supplying the power that the thermostat needs. Call an HVAC contractor to inspect the safety mechanism.
Faulty Wiring or Equipment: Bad wiring can prevent power from reaching your thermostat. It can also increase the risk of a short circuit or fire. Check whether the thermostat’s wiring is frayed, broken, or installed incorrectly (the wires/terminals are usually color-coded). It’s also possible the transformer has gone bad. Thermostats have a finite lifespan as well; if your device has stopped working, consider investing in a programmable or smart thermostat that can be controlled remotely and help you save energy.

You can determine if the wiring is defective by turning the fan from the “Auto” setting to the “On” setting. The blower should start, which means your thermostat is getting power. Or, if the AC is on, turn the temperature down; if the furnace is on, turn the temperature up. The level must be higher/lower than the current room temperature. If the thermostat is receiving power, your HVAC system should start up.

There are also more complex tests that involve checking the wire connections, disconnecting them, or using a multimeter. Unless you’re familiar with wiring in general, it’s best to consult a professional.

Call NEXGEN If No Power Is Coming to Your Thermostat