AC Won't Kick On? Here's Why

There’s nothing more frustrating than an AC that won’t turn on in the middle of the summer. It’s easy to start worrying about repair costs or whether you might need to replace your entire system. 

But, before you panic, know this: there’s usually a simple fix. This troubleshooting guide will help you figure out what’s going on with your AC and how to get it back up and running fast. 

Common Reasons Why An AC Won’t Turn On 

Several issues can lead to your AC not turning on. Some are easy to fix, and others require more extensive repairs. 

Here’s what we see most often in homes throughout Maryland and Delaware:

1. Thermostat Issues 

Your thermostat is the brain of your cooling system. If it’s not working properly, your AC won’t know when to turn on. Here’s what to look for: 

• Dead batteries - This is often overlooked. Try swapping in fresh batteries.
• Incorrect settings - Make sure it’s set to “cool” and that the target temperature is below the current room temperature.
• Faulty thermostat - Older or damaged thermostats can malfunction. If you’re not getting any response, it may need to be replaced.

2. Electrical Problems 

Your AC system relies on electricity to function, and electrical issues are a frequent culprit when systems won’t start.

• Tripped circuit breaker or blown fuse - A power surge can trip your breaker, causing your AC to shut off. 
• Wiring issues - Over time, wires can become damaged or loose, especially in older systems. If the wiring looks frayed or damaged, it’s likely the problem.

3. AC Unit Issues 

If your thermostat is set to cool but the AC is not turning on, there might be an issue with the unit itself. Some common problems to look for include: 

• Clogged Air Filter - Dirty filters restrict airflow. If the clogging is extreme, it can cause the system to shut down. 
• Dirty Evaporator Coil - Dust and grime can build up on your evaporator coil, which can affect your AC system’s performance. 
• Low Refrigerant Levels - Without enough refrigerant, your AC can’t do its job, and it might shut off altogether.
• Clogged Condensate Drain Line - A blocked drain can cause the unit to trigger a safety switch that prevents it from running until the issue is resolved.

4. Age 

Sometimes, the AC isn’t kicking on because it’s simply reached the end of its life. If your system is over 10–15 years old and frequently breaks down, it may be time to consider a replacement. It’s frustrating, but it can also be a great opportunity to upgrade your cooling system. 

Total Home Performance can help you weigh your options and choose the best replacement, whether that’s a high-efficiency central AC system, a ductless mini-split AC, or a whole-home heat pump that can handle both heating and cooling.

What to Do When Your AC Won’t Turn On

Before you panic, walk through these quick troubleshooting steps: 

1. Check thermostat - Make sure it’s set to cooling mode and set lower than the temperature outside. If it isn’t lighting up, try replacing the batteries. 
2. Check breaker panel - Open up your electrical panel and reset any tripped breakers. 
3. Replace the air filter - Take out your air filter and clean or replace it, according to the manufacturer's instructions. 
4. Check the outdoor unit - Clear away any overgrown landscaping or other debris that’s blocking your outdoor unit. 
5. Still nothing? - Call Total Home Performance. We’ll take a look and let you know whether a replacement is in order. 

Stay cool this summer with a new AC or heat pump. Call 410-822-1390 or contact us for a free consultation and estimate.