10 of the Most Common AC Issues — and How to Fix Them Yourself

by Rowan Guthrie
outdoor unit of the air conditioner

When summer’s scorching heat arrives, a malfunctioning air conditioner can turn your home into a sweltering sauna. You should be able to rely on your air conditioning system, but sometimes they develop problems — and it’s often at the worst moment.

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These are some of the most common issues homeowners often face with air conditioners. The good news? Most of these you can fix yourself without calling an HVAC technician.

1. Clogged Air Filters

If your central AC system isn’t cooling your home like it should, a clogged air filter is a likely culprit. Over time, filters become congested with dust, dirt and debris, restricting airflow.

Remedy: Locate the air filter (it’s usually near the return air duct or furnace) and replace it with a new one. You should replace an air filter every two to three months, depending on usage.

2. Air Conditioner Refrigerant Leaks

Your air conditioner won’t be able to cool the air effectively if it’s low on refrigerant. This affects the AC’s performance and increases energy consumption, making it cost more to operate.

Remedy: Detecting the leak and recharging the system with the correct amount of refrigerant requires specialized equipment and expertise, so this job is best left to HVAC professionals.

3. Frozen Evaporator Coils

Frozen evaporator coils can hinder the system’s ability to cool the home and may cause damage to the compressor. Common causes include insufficient refrigerant and blocked airflow.

Remedy: If ice forms on the evaporator coils, turn off the AC and let the ice melt. Check for obstructions that may be restricting airflow, such as dirty filters or blocked vents. If this doesn’t fix the problem, you should call a professional.

4. Faulty Capacitors

Capacitors provide the electrical jolt that starts your AC’s motors. When they malfunction, your AC might struggle to turn on or may not function at all.

Remedy: Only people with the right electrical knowledge and understanding of safety precautions should replace capacitors themselves. Otherwise, hire an HVAC technician to avoid potential system hazards and personal harm.

5. Malfunctioning Compressor

The compressor is your air conditioner's heart, responsible for pumping refrigerant and facilitating the cooling process. When it fails, your AC won't cool effectively.

Remedy: Repairing or replacing a compressor is a complex task that should always be left to professionals.

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6. Tripped Circuit Breaker

If your AC suddenly stops working, check your circuit breaker to see if the AC's breaker has tripped.

Remedy: If the breaker has tripped, switch it off and then back on. If it trips again, there may be an underlying electrical problem that you should leave to a professional.

7. Thermostat Issues

A faulty thermostat can cause your AC to behave erratically, leading to inconsistent temperatures or improper cooling.

Remedy: Ensure your thermostat is set to "cool" and the desired temperature, and remove any dirt or debris. If problems persist, consider replacing the thermostat or arranging an inspection from an HVAC technician.

8. Dirty Condenser Coils

Dust and debris can accumulate on the condenser coils, reducing their ability to release heat, which hinders the cooling process.

Remedy: Turn off the power to the AC and clean the condenser coils using a garden hose or coil-cleaning solution. If you aren't comfortable doing this yourself, contact an HVAC technician.

9. Noisy Operation

If your AC is making strange noises, such as banging, rattling or screeching, it might be because one or more components have become loose or damaged.

Remedy: Unless the source of the noise is obvious, it’s usually best to call an HVAC technician. They can diagnose the issue, tighten loose parts and replace damaged components.

10. Dirty or Blocked Condensate Drain

Over time, the condensate drain line can become clogged with algae, mold or debris. This can cause leaks and potential water damage.

Remedy: Clear obstructions by flushing the condensate drain line with a mixture of water and vinegar. If you aren't sure how to do this, you can hire an HVAC technician to do it for you.

Regular maintenance and timely repairs will help keep your AC system running optimally and extend its lifespan. You can save money if you know how to fix a problem without damaging the system, but calling an HVAC technician will be safer and cheaper in the long run if you don't.

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