Signs Your AC Needs Repair: 8 Warning Signs Charlotte Homeowners Shouldn't Ignore

Your air conditioner rarely fails without warning. In most cases, there are signs something's wrong days or weeks before a complete breakdown. The key is recognizing these warning signs early—before a minor repair becomes a major expense, or worse, a complete system failure on the hottest day of summer.

Here are the eight warning signs that mean it's time to call for AC repair. We've ranked them by urgency so you know which problems can wait and which need immediate attention.

1. Warm Air Coming from Vents (Urgency: High)

If your AC is running but blowing warm or room-temperature air, something is definitely wrong. This is one of the most common repair calls we receive, and it can indicate several issues:

• Low refrigerant (often from a leak)
• Frozen evaporator coil
• Compressor problems
• Thermostat malfunction
• Restricted airflow from dirty filter

2. Unusual Noises (Urgency: Medium to High)

Your AC should run relatively quietly. New or unusual sounds often indicate mechanical problems that will worsen without repair:

• Grinding – Usually indicates motor bearing failure. Stop running immediately.
• Squealing – Belt issues or motor problems. Service soon.
• Banging/Clanking – Loose or broken parts inside the unit.
• Buzzing – Electrical issues or failing contactor.
• Hissing – Possible refrigerant leak. Call immediately.
• Clicking (constant) – Relay or control problems.

Pro tip: The location of the noise matters. Outdoor unit noises often indicate compressor or fan motor issues. Indoor noises typically point to blower motor or ductwork problems.

3. Weak or Reduced Airflow (Urgency: Medium)

If you notice less air coming from your vents than usual, your AC has to work harder to cool your home. Common causes include:

• Clogged air filter (check this first—it's free to diagnose)
• Blocked or leaky ductwork
• Failing blower motor
• Frozen evaporator coil restricting airflow
• Debris blocking outdoor unit

4. Short Cycling (Urgency: High)

Short cycling is when your AC turns on and off frequently—every few minutes instead of running for 10-15 minute cycles. This wastes energy, wears out components faster, and prevents proper cooling.

Short cycling is often caused by:

• Oversized AC system (too much capacity for your home)
• Low refrigerant causing the compressor to overheat
• Dirty air filter restricting airflow
• Faulty thermostat or thermostat in bad location
• Electrical problems
• Frozen evaporator coil

5. High Humidity Inside (Urgency: Low to Medium)

Your AC does more than cool—it removes humidity from the air. If your home feels sticky or clammy even when the AC is running, the system isn't dehumidifying properly.

Possible causes include:

• Oversized system that cools too quickly without removing humidity
• Refrigerant issues
• Aging system losing efficiency
• Thermostat fan set to "ON" instead of "AUTO"

In Charlotte's humid climate, proper dehumidification is essential for comfort. Indoor humidity should stay between 30-50%.

6. Water Leaks Near Indoor Unit (Urgency: Medium)

Some condensation is normal, but water pooling around your indoor unit indicates a problem with the condensate drain system. Left untreated, this can cause water damage and mold growth.

Common causes:

• Clogged condensate drain line (very common in humid climates)
• Cracked or overflowing drain pan
• Frozen evaporator coil thawing and overwhelming the drain
• Improper installation

7. Strange Odors (Urgency: Varies)

Unusual smells from your AC should never be ignored:

• Musty/moldy smell – Mold or mildew in ductwork or on evaporator coil. Common but needs attention.
• Burning smell – Electrical issue or overheating motor. Turn off system immediately.
• Rotten egg smell – Possible dead animal in ductwork. Unpleasant but not dangerous.
• Chemical smell – Refrigerant leak. Leave area and call for service.

8. Higher Energy Bills (Urgency: Low)

If your electric bill has increased significantly without a change in usage patterns, your AC may be losing efficiency. This often happens gradually as systems age or components wear out.

An AC working harder to produce the same cooling will use more electricity. Common efficiency killers include:

• Dirty coils (evaporator and condenser)
• Low refrigerant
• Worn capacitors or motors
• Duct leaks
• Aging equipment past its prime

When to Call vs. When to Wait

How Much Will AC Repairs Cost?

Frequently Asked Questions