Why Is My AC Making a Clicking Noise?
July 29, 2020
If you hear a faint click or two when your air conditioner starts up, you probably have nothing to worry about. That’s just your thermostat signaling your system to cycle on. However, if you hear prolonged clicking noises and/or your AC is not cooling your home, there’s an issue with your system.
An audible clicking noise is usually caused by an electrical issue. However, there could be a variety of other reasons that you’re hearing a clicking noise coming from your AC system, including:
- Faulty Contactor
- Dead Capacitor
- Thermostat issue
- Loose fan
Below, we’ll dive into each of these issues in a little more detail so you can get a better idea of why your AC may potentially be making a clicking noise and what you can do to fix it.
f you’d rather have a professional take a look at your AC, Patrick Riley technicians are here to help. We’ve been around for over 30 years, so we have solutions for all types of clicking or clunking noises. For our general AC repair pricing and process, you can check out our AC repair page.
Clicking Noise #1: Faulty contactor
Your contactor plays the role of “operator” when it comes to your AC system. Your thermostat calls for cool air, and your contactor is in charge of turning on your outdoor AC unit.
If your contactor is broken, malfunctioning, or simply worn out, your outdoor AC unit won’t be able to receive any signal from your thermostat. This can result in your AC making a clicking noise as the system tries to start but can’t.
If you think you may have a bad contactor, reach out to a Patrick Riley professional by calling 602-286-0027 or scheduling an appointment online. This piece of your AC unit can store a high voltage, and attempting to repair or replace a contactor without precaution could result in an electrocution or in damage to your AC system.
Clicking Noise #2: Dead capacitor

The capacitor is essentially a large battery that helps “start up” your outdoor unit.
Just like any battery, over time, capacitors lose their charge, and the clicking noise from the AC you’re hearing is usually an indication your outdoor AC unit is attempting to turn on but is unable to start.
Alternatively, capacitors can also die out prematurely. So if you remember getting a new one in the past couple years, it could have experienced physical damage, overheating, or a greater voltage than it can handle.
If you think you may have a dead capacitor, you’ll need to reach out to a Patrick Riley HVAC expert for a successful AC replacement.
Clicking Noise #3: Thermostat Issue
If the problem is neither the contactor nor the capacitor, you're likely dealing with a thermostat issue, such as a broken relay or worn-out wiring.
When your unit is running normally, you should hear a soft clicking sound when your thermostat tells your conditioner to boot up. That noise comes from the relay opening to power on your unit. However, if the relay is broken or there's a wiring issue, the relay will continue to open and attempt to send power to your AC despite an inability to start.
Like the other audible issues, both of these repairs (broken relay or wiring issue) will have to be done by an HVAC technician that can properly diagnose and solve the issue. If you think your thermostat is the culprit, you’ll want to reach out to Patrick Riley to have an expert come and take a look.
Clicking Noise #4: Loose Fan

If you hear your outdoor AC unit making a clicking noise, it could be that the fan inside is loose.
If your fan becomes loose for some reason, it can hit the casing of your outdoor unit when your AC is running and create a kind of clicking or tapping noise. This causes damage to the inside of the unit and its blades, and it limits the cooling capabilities of your system overall.
This is an easy fix for an HVAC professional. Patrick Riley technicians can take your AC unit apart, determine if the belt can be tightened or if your fan blades need replacing.
Still having issues with your AC system? Reach out to Patrick Riley
If you’re regularly hearing an AC clunk or clicking noise like those described in the issues above, you’ll need a professional to come and fix it. Schedule a repair today! Luckily for you, we know our way around all kinds of cooling machines. Homeowners in Phoenix, Mesa, Chandler, and surrounding Arizona cities trust the quality of our work, whether it’s furnace, HVAC, or plumbing repairs.
Why Choose Patrick Riley
Choosing a Patrick Riley technician comes with many benefits compared to choosing a competitor in central Arizona. We have friendly technicians all across Maricopa County to ensure your HVAC repair is done quickly, painlessly, and to your complete satisfaction. Best of all, we go out of your way to give you the best deal possible. Sign up for a flexible payment plan, check our Coupons page for this month’s savings opportunities, or consider a VIP Maintenance Plan for scheduled maintenance and exclusive discounts.
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- Troubleshooting