Heat Pumps
AC Clicking But Not Turning On: Common Causes and Solutions
By Jonathan Poston•March 4, 2025
Hearing your air conditioner make a clicking noise but not turn on can be frustrating and lead to significant comfort issues, especially during the summer. HVAC.com highlights a few common reasons why your AC might click without turning on to help you restore your system to proper working condition.
When Clicking is Normal
If your air conditioner clicks and then turns on, it’s usually nothing to worry about. A single click is often just the sound of the system’s electrical components engaging as the AC starts up. This initial click is a normal part of the startup process, especially when the system powers on for the first time each day. It’s simply the sound of the compressor or contactor coming to life.
However, if you hear multiple clicks or if the AC continues to click without turning on, it’s a sign that something might be wrong. In most cases, if the AC is clicking but not starting, it means the system isn’t receiving the proper signal or power to operate. In those cases, it’s important to troubleshoot further or contact a professional to inspect the system.
Why Is My AC Clicking and Not Turning On?
1. Tripped Circuit Breaker or Blown Fuse
A tripped circuit breaker or a blown fuse can cut power to your air conditioning unit, preventing it from turning on. In some cases, the AC may try to start, making a clicking noise, but without sufficient power, it can’t engage.
Solution: Check your circuit breaker panel to see if the breaker for the AC unit has been tripped. If it has, simply flip it back to the “on” position. If you find a blown fuse, you’ll need to replace it.
2. Faulty Capacitor
The capacitor provides the electrical charge needed to start your air conditioner’s motor. If the capacitor is faulty, your AC may click but fail to turn on because it can’t provide the necessary power to the motor.
Solution: A bad capacitor is a fairly common issue. Capacitors can store electrical energy and pose a risk if mishandled, so it’s best to have a professional inspect and replace it.
3. Frozen Coils
Frozen evaporator coils are another common cause of an AC clicking but not starting. When the coils freeze, the air conditioner can’t circulate refrigerant properly, which can lead to the unit trying to start but failing. You might hear clicking as the system struggles to turn on.
Solution: If the coils are frozen, turn off the AC and allow them to thaw. Factors like low refrigerant levels, a faulty thermostat, a clogged air filter, or issues with the blower motor can contribute to frozen coils. Once the coils are thawed and the filter is cleaned or replaced, restart the system. If the problem persists, contact a technician for further inspection.
4. Faulty Thermostat
If the thermostat is malfunctioning, it may cause your AC to click but fail to turn on. This could be due to dead batteries, a dirty sensor, or wiring issues.
Solution: Check the thermostat’s battery and replace it if needed. You can also try cleaning the thermostat’s sensors, as dirt and dust can cause improper readings. If the thermostat still isn’t functioning properly, you may need to replace it. A new thermostat could restore proper communication between your home’s cooling system and the AC unit.
5. Relay or Control Board Failure
The relay or control board of your AC acts as the brain of the system, directing various components to turn on or off. If there’s a failure in the control board or relay, your AC may try to start but end up clicking without actually running.
Solution: A malfunctioning control board is more complex to diagnose and repair. If you suspect this is the issue, it’s best to call a professional technician. A technician can test the control board and determine whether it needs to be repaired or replaced.
Potential Issues If the AC Is Left Unrepaired
If your AC unit is clicking but not running, it can lead to several problems if left unaddressed:
- Increased Energy Costs: If your AC is repeatedly trying to start, it may consume more electricity, driving up your energy bills even though it’s not functioning properly.
- More Extensive Damage: If ignored, issues like a faulty capacitor or control board can worsen over time, potentially causing even more damage to your AC unit and leading to a complete breakdown.
- Discomfort in Your Home: During hot months, a non-functioning AC unit can make your home uncomfortable, especially if temperatures are rising. Prolonged heat exposure can also cause health risks for vulnerable people, such as children, the elderly, or those with respiratory issues.