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Your AC Isn’t Turning On. Is the Capacitor to Blame?

Your AC Isn’t Turning On. Is the Capacitor to Blame?

August 14, 2025

During a hot Arkansas summer, the last thing you want is an AC unit that won’t start. But if you’re hearing a hum or nothing at all, it could mean your system’s capacitor has failed.

Capacitors are a small but essential part of every HVAC system, and they’re one of the most frequent causes of AC breakdowns we see in Jonesboro, Wynne, and surrounding communities.

Understanding the Role of the Capacitor

The capacitor’s job is to give your AC unit the power boost it needs to start up. It stores electrical energy and releases it when your air conditioner needs to kick into gear.

Capacitors help start or run:

  • The compressor
     

  • The outdoor condenser fan
     

  • The indoor blower motor
     

If your system tries to turn on and struggles, stalls, or makes a humming sound—chances are, the capacitor is failing.

Why Do HVAC Capacitors Fail?

Capacitors are vulnerable components for several reasons:

Extreme Heat

High temperatures cause the dielectric fluid inside to degrade, which reduces the capacitor’s ability to hold a charge. Over time, the internal plates can warp, swell, or separate.

Electrical Stress

Frequent on-off cycles, power surges, or voltage fluctuations (like from summer storms or unstable grids) can cause wear or even sudden failure.

Aging Equipment

Capacitors naturally lose effectiveness over time. Even well-maintained systems will eventually need a replacement capacitor.

Inferior Materials

Older systems or lower-cost installs might use cheaper capacitors that simply don’t hold up well under load.

Prevent Failures Before They Happen with the Mohr Peace of Mind Program

Here’s the best part: Most capacitor issues can be prevented altogether with Mohr’s Peace of Mind Agreement (MPOM).

Through regular tune-ups and system inspections included in the program, our team can:

  • Catch weak capacitors before they fail and leave you sweating
     

  • Clean and maintain your coils, improving airflow and reducing overheating that wears capacitors down
     

  • Spot corroded wires or loose connections during inspections that would otherwise stress electrical components
     

Most capacitor problems we see would have been avoided with a Mohr Peace of Mind tune-up.

Replacing a Capacitor: Don’t Try This at Home

Even if you’re comfortable with DIY repairs, HVAC capacitors are dangerous to handle. They store voltage long after power is turned off, and touching the terminals can result in a powerful shock.

To replace one safely, a technician must:

  • Use insulated tools
     

  • Discharge the capacitor
     

  • Verify and match specs
     

  • Reconnect wires correctly (a wrong connection could damage the motor)
     

At Mohr, we take every precaution to ensure safe, code-compliant repairs.

Call Mohr Air Conditioning for AC Repairs in Northeast Arkansas

Don’t let a failed capacitor keep you sweating. Mohr’s experienced HVAC technicians can test, diagnose, and fix the problem fast so you can stay comfortable.

Contact Mohr today to schedule AC service in Jonesboro, Wynne, and the surrounding areas.