8 Reasons Why Your AC Unit Won’t Power Up

The sweltering summer heat starts creeping indoors. Yet, your air conditioner won’t respond to the rising temperatures, forcing you to schedule AC repair in Dayton, Ohio. “Why is my AC unit not turning on?” you wonder aloud, perspiration forming on your forehead. 

At A1 Mechanical Heating & Cooling, many of our customers ask the same question about their HVAC systems. We’ll outline the reasons your cooling system might not cycle below.

Why Is My AC Unit Not Turning On? 8 Possible Reasons

If the AC stopped working, you’ll have to investigate to find possible causes. Let’s troubleshoot your cooling system below to get to the heart of the problem. 

1. Thermostat Issues

The thermostat kickstarts your cooling system’s cycles by signaling temperature fluctuations that trend above your settings. Even if your device worked swimmingly for as long as you can remember, a random thermostat malfunction can still throw your HVAC system off. 

The following problems might manifest and prevent your device from communicating with the unit:

• Dirty temperature sensors
• Disconnected wires
• Dead batteries
• Offline system

Schedule a tune-up so your HVAC technician can calibrate or reset the thermostat. If you’re still wondering, “Why is my AC unit not turning on?” proceed to the next item on our list. 

2. Airflow Restrictions 

Many components can restrict airflow if they get dirty enough, but the air filter is the one that you can more easily address. Sometimes, your unit will stop running to protect itself from excessive air resistance. A dirty filter contributes to resistance because the return register can’t pull enough air through without stressing blower components. 

Check and change your air filter to see if it solves the problem. Otherwise, let’s move forward with other solutions.

3. Electrical Disconnections

Your air conditioner depends on a steady supply of electricity to make the fan blades turn, the motor power the system, and the rest of the components to do their jobs. Did your power go out? Investigate the power issue to see if it stems from the following:

• Blown fuse: Familiarize yourself with your system’s layout via the user manual. You can check its fuses inside the control board. 
• Tripped breaker: Go to your breaker box to see if a switch has shifted. Turn it back to the correct position and see if your air conditioner turns back on. 
• Wiring issues: Inspect the outdoor unit for corrosion, frayed wires, and other potential concerns.

When dealing with electrical concerns, reach out to your local HVAC technician for help. You should only reset a tripped breaker. The other two issues require professional attention since they deal with sensitive and potentially dangerous HVAC components. 

4. Clogged Condensate System

Did you know your HVAC system has a plumbing infrastructure? It’s true!

Heating and cooling cycles create moisture. The condensate system, which works like a miniature drainage pipe, collects that moisture and deposits it away from the equipment. 

Sometimes, scummy debris falls into the drain pan and eventually flows into the drain line along with the water. When debris becomes lodged inside the line, it causes a backup. Eventually, the drain pan overflows.

“Why is my AC unit not turning on? What does HVAC plumbing have to do with it?”

Modern cooling equipment can detect abnormally high water levels in the drainage pan. It will stop cycling and shut down to prevent circuit shorts and other electrical issues that the water could cause. Your technician can easily dislodge the clog and drain the pan before restarting the system. 

5. Failed Capacitor

Perhaps your air conditioner starts a cycle but stops short and barely impacts the indoor temperature. This symptom might indicate a capacitor failure. But the question is, which capacitor is the problem?

Most cooling systems have two. One gives the equipment a jolt of energy to start up. The other maintains power while the air conditioner runs.

Either capacitor could force your system to stop short or keep it from running at all. Only skilled hands should handle these delicate components, so let your A1 Mechanical Heating & Cooling technician deal with the issue. 

6. Compressor Problems

The air conditioning motor, also called the compressor, can absolutely keep your cooling system from running. “Why is my AC not turning on?” Try to remember if you noticed the symptoms listed below before the system failure:

• Lukewarm air when crisp, cool air should flow
• Jarring noises like harsh, grinding sounds or persistent rattling
• Constant breaker trips despite no notifications about power grid issues
• Poor airflow moving through your vents

Each of these issues means your faulty compressor is headed directly toward a complete failure.

7. Leaky Refrigerant Lines

When you notice your AC not working and temperatures rising in your building, contact an expert to check your system’s refrigerant levels. Your system depends on refrigerant to absorb heat from your building’s interior and transfer it away from the air-conditioned rooms. Every HVAC system needs a specific amount of refrigerant to function. 

Leaky lines allow the substance to escape and evaporate into the atmosphere. That means less comfort, plummeting efficiency, and fatigued HVAC equipment. An HVAC technician can replenish the refrigerant supply, mend the line, and check other components, like the evaporator coil. 

8. Choked Evaporator Coil

The evaporator coil performs two functions. First, it removes heat from and compresses the refrigerant into a gas. Second, it absorbs moisture from the refrigerant before sending it into the drain line. 

If this coil becomes encased in dust and other filth, it becomes choked and can’t function properly. Schedule regular maintenance to prevent frozen or filth-covered coils and to keep other components in pristine condition.

Contact A1 Mechanical Heating & Cooling for AC Repair in Dayton, Ohio

“Why is my AC unit not turning on?”

A1 Mechanical Heating & Cooling gave you insight into the reasons why. We also answer other questions, like, “Can a power outage damage the AC?” Call (937) 865-2325 if your HVAC system isn’t working properly and you need expert AC repair in Dayton, Ohio.