The clicking of the thermostat before the AC turns on can be a comforting sound, reassuring us that cool air is on the way. So much so that if you hear the clicks with no result, it can be a cause for alarm. Fortunately, there are some simple ways to troubleshoot when the thermostat clicks but AC does not turn on. From checking the air filters to assessing the capacitor, here’s how to solve the problem.

Thermostat Clicks But AC Does Not Turn On? Try These Troubleshooting Tips

Usually, the most common reasons your thermostat clicks but AC does not turn on have simple fixes. Our troubleshooting tips can help determine if some basic maintenance or a professional repair is needed.

Replace the Air Filters

Clogged air filters are one of the most common reasons a thermostat clicks but AC does not turn on. A filter cleans the air before it circulates throughout your home, trapping dirt particles, dust, and pollen. Over time, these contaminants will clog the filter, limiting airflow to the HVAC system or furnace. If airflow is restricted, it’s harder for the system to generate heat or cool air.

To avoid this problem it’s recommended that you replace the air filter every 60-90 days. When changing the filter, we recommend investing in a high-quality model that can screen out a range of particulates.

Adjust the Thermostat Settings

When the thermostat clicks but no air comes out of the vents you may want to take a look at your thermostat settings. If you want the AC to turn on, the thermostat’s set temperature should be low enough that it triggers the system to start. Similarly, if you want the heat to come on, make sure the set temperature is high enough. If the room temperature already matches the thermostat setting, neither the heat nor the AC will turn on.

In addition to the temperature setting, make sure the thermostat is seasonally adjusted to the HEAT or COOL option. Check the fan to make sure it’s set to ON or AUTO for proper airflow.

thermostat clicks but ac does not turn on

Check the Thermostat

What if the thermostat clicks but no AC even after changing the filter and checking the settings? It’s possible that the thermostat has malfunctioned. Oftentimes this is due to a broken relay system. Relays are how the thermostat communicates with the HVAC or furnace, with certain wires turning on the heat and others signaling the flow of cool air.

Here’s how you can determine if your home thermostat is bad:

  • Check thermostat wiring, tightening any loose relay connections, and assessing for signs of damage.
  • Turn the thermostat’s breaker off from your home circuit breaker box. Wait 1-2 minutes before turning it back on. If the thermostat doesn’t start up properly or at all, it may be faulty.
  • Evaluate any new sounds. If the thermostat clicking is louder than usual and all other systems are functioning normally without unusual noises, the thermostat is likely malfunctioning.

We recommend that you have a professional servicer address any thermostat issues.

Check the Capacitor

Lastly, if you hear your thermostat click but no heat or cool air comes on, a faulty capacitor may be the problem. The capacitor essentially functions as a battery. It stores the electrical charge used to start the compressor at the thermostat’s signal for cool or warm air.

If you hear a buzzing noise along with your thermostat clicking, a defective capacitor is likely the problem. This buzzing is the sound of the compressor trying to start without the necessary electrical charge. We strongly suggest that a professional service address any capacitor concerns, as its stored voltage can cause an electrical shock if handled improperly.

Dependable Heating & Air can handle any thermostat concern. Call us if the thermostat clicks but AC does not turn on or for any AC repair.