3 Common Reasons a Home A/C Will Overheat and Shut Down

The hot summers of central California are no joke. Most of us rely on our air conditioners to make the evenings tolerable. What do you do when your AC keeps shutting down? Service Champions AC and HVAC technicians get asked this a lot. Let’s go over the top three common reasons your outside AC unit is overheating.

Common Reasons for A/C Overheating

When your AC unit overheats, safety measures kick in to interrupt the power. The power remains off until you manually reset your AC unit. 

The compressor is the engine or heart of your AC unit. When you turn your AC on and hear a buzzing or humming, that's your compressor working. When the AC compressor overheats, it short cycles and turns off. A dirty air filter, dirty condenser coils, and low refrigerant all cause your compressor to overwork and short cycle. 

Short cycling is particularly common at the beginning of the season. One of the three issues below is likely causing your AC unit to overheat.

1. Dirty air filter

The air filter is the safety net that protects your air conditioner from dirt and pollutants.

A dirty air filter reduces airflow to the system, strains the fan motor, and forces your air conditioner to run longer — and harder — to cool your home. A dirty air filter also traps cool air in the unit, leading to ice forming on the evaporator coils. This makes it harder for the compressor to do its job.

Overworking leads to increased utility bills, and Californians already pay some of the highest energy rates in the country. Your unit will continue to overwork until:

  • The air conditioner breaks down

  • The air conditioner overheats and short cycles (turns off)

2. Dirty condenser coils

Condenser coils are tubes running through the outside part of your air conditioner. They’re the counterpart to the evaporator coils inside the unit. The evaporator coils remove heat by exchanging cooled refrigerant for gas. That hot gaseous refrigerant travels to the condenser coils, where the fan cools the gas, returning it to liquid refrigerant that travels back to the evaporator coils. 

During the winter months, dust and debris collect around the outside unit, in the compressor fins, and around the coils. This build-up acts as an insulator, and the refrigerant can't effectively release the heat. Your compressor will keep running until it overheats because it can’t reach your thermostat temperature setting.

3. Low refrigerant

Air conditioners use refrigerants to remove heat from your home. This coolant cycles back and forth through your system. Refrigerants don't get used up like gasoline in a car. The closed system recycles the same coolant again and again. 

However, your AC system experiences wear and tear over time, and parts degrade. Fittings get loose, valves become faulty, and leaks can occur. As your refrigerant leaks, the compressor struggles to maintain pressure, causing the system to lose its ability to effectively cool. Your AC works harder to meet demand, eventually overheating and short cycling.

Signs and Symptoms

If your system is overheating, you've likely had this problem for a while. We get it — it's not always easy to tell the difference between normal wear and a symptom of a bigger issue. Below are some signs and symptoms associated with a dirty air filter, dirty condenser coils, and low refrigerant levels.

  • Decreased airflow – A clogged air filter decreases the airflow to the unit, leading to a cascade of issues, including an overheating compressor and lukewarm air blowing into the home.

  • Condenser coils are covered in ice – Decreased airflow causes cool air to hover around the coils, freezing the condensation.

  • Pooling water within the unit and the drain pan – When the condenser coils freeze and thaw, pooling water can leak out of the unit and drain pan. 

  • Hissing or bubbling sounds – These sounds are common with leaking refrigerant. You won’t see pooling refrigerant because it evaporates quickly. 

  • Higher electricity bills – An overworked system increases your electricity bills.

  • Burning smell - An overworking compressor can produce a burning smell like melting rubber.

Preventive Maintenance Tips

The average AC unit lasts 8 to 10 years. Regular servicing decreases the need for repairs and lets you enjoy a cool home for the duration of your AC system's service life. Follow these preventative maintenance tips to prevent your AC unit from overheating.

Change your air filter

Changing the air filter can be done without the help of a technician. Change your AC air filter every three months and after a wildfire. Wildfires increase particle pollution in the air and clog your filter faster. 

Clean your AC unit

Clean the area around your outside unit to limit dust and dirt build-up on the condenser coils. Remove the exterior cover to clean the condenser coils, and use a fin brush to remove the build-up between the condenser fins.

Call a professional

If you have a refrigerant leak in your air conditioning unit, it's time to call a professional. Refrigerant is not something you can top up – if it's low, your system likely has a leak. An HVAC technician can troubleshoot the issue, locate and repair any leaks, replace the refrigerant, and set the pressure.

Why Choose Service Champions For Your AC Needs?

When you need inside and outside air conditioner overheating solutions, call our team at Service Champions. We offer online scheduling, award-winning service, payment plans and financing options, and a 100% money-back guarantee. Sign up for our MVP+ package for whole-home servicing, priority care, and deep discounts on parts and installations.

The team at Service Champions is your local heating and air conditioning company, serving San Jose, Sacramento, East Bay, and the surrounding areas. For more information on any of our products or services, contact us today.

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