AC Compressor Not Turning On: 5 Easy Troubleshooting Steps

AC compressor not turning on? Don’t break a sweat. We’ll take you from meltdown to cool down with 5 easy troubleshooting steps.

AC Compressor Not Turning On
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Steps to Troubleshoot AC Compressor Not Turning On

Let’s jump right in and take you through the steps to resolve this problem.

Checking the Thermostat

Start with the simple stuff. Check that your thermostat is set to cool and the temperature is set lower than the room temperature. If that’s all good but your AC compressor is still not kicking in, it’s time to dig deeper.

Inspecting Electrical Components

Remember, your AC unit needs electricity to work. Check your circuit breaker or fuse box to make sure there’s no issue there. If you’re comfortable doing so, you can also check the wiring within your AC unit for any obvious issues like loose connections or frayed wires.

Evaluating the Capacitor and Contactor

Check the capacitor and contactor next. If your capacitor is swollen or leaking, it’s likely bad. The contactor should be clean and free of any pitting. If you’re not sure, it’s best to call in a professional to avoid damaging these components.

Identifying Refrigerant Leaks

Refrigerant leaks can be tricky to spot. Look for oil stains, hissing noises, or ice on the refrigerant lines. If you suspect a leak, don’t try to fix it yourself. Refrigerant is a hazardous substance and should only be handled by a professional.

Overheating Assessment

If your AC compressor is overheating, you might see signs like a tripped breaker or a humming noise from the unit. If you suspect overheating, turn off your AC unit and call a professional. Overheating can cause serious damage to your compressor.

When to Call a Professional

It’s time to call in the pros if your AC compressor still won’t turn on after you’ve done some basic troubleshooting. Other signs you need a professional include a tripped breaker, ice on the refrigerant lines, or a hissing noise from your AC unit.

While it’s great to understand how your AC unit works, keep in mind that some repairs should be left to professionals. Refrigerant handling, electrical repairs, and replacing components like the compressor, capacitor, or contactor can be dangerous if not done correctly.

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Why Your AC Compressor Is Not Turning On

Now, let’s turn our attention to the culprits responsible for the problem in the first place.

Thermostat Issues

You wouldn’t believe how often the problem is as simple as a misbehaving thermostat. The thermostat is the boss of your AC unit, telling it when to start and stop. If it’s set incorrectly or not working properly, your AC compressor won’t turn on.

Incorrect Thermostat Settings

It may seem obvious, but make sure your thermostat is set to cool and the temperature is set lower than the room temperature. If not, your AC unit will be on a permanent break.

Faulty Thermostat

If your thermostat settings are correct, but your AC compressor is still not kicking in, you might have a faulty thermostat. This can happen due to wiring issues, dead batteries, or just old age.

Electrical Problems

Electricity is the lifeblood of your AC unit. Without it, your compressor just won’t kick in. Electrical issues can range from problems with your circuit breaker to faulty wiring within the unit itself.

Circuit Breaker and Fuse Issues

Your AC unit is a power hog. If there’s a power surge or if your unit is pulling too much power, it can trip the circuit breaker or blow a fuse. This is a safety feature to prevent electrical fires. But when it happens, your AC compressor won’t turn on.

Wiring Problems

Wires are like the highways of electricity. If there’s a roadblock or a pothole, electricity can’t get to where it needs to go. Loose connections, frayed wires, or corrosion can all interfere with the electricity supply to your compressor, keeping it from turning on.

Capacitor or Contactor Failures

The capacitor and contactor are like the starting blocks for your compressor. The capacitor provides the initial jolt of electricity to start the compressor, and the contactor controls the flow of electricity. If either of these components fails, your compressor won’t start.

Bad Capacitor

A bad capacitor is like a car with a dead battery. It just won’t start. The capacitor stores and releases the electricity needed to start and run the compressor. If it’s not working properly, your compressor won’t turn on.

Defective Contactor

The contactor is like the gatekeeper of electricity for your compressor. It opens and closes to allow electricity to flow to the compressor. If it’s defective, it can keep the gate closed, preventing your compressor from starting.

Refrigerant Leaks

Refrigerant is the secret sauce that makes your AC unit cool your home. It absorbs heat from inside your home and releases it outside. But if there’s a leak in the system, your AC compressor might not turn on.

Signs of Refrigerant Leaks

If your home isn’t getting cool, even when the AC is running, you might have a refrigerant leak. Other signs include ice on the refrigerant lines or hissing or bubbling noise from the AC unit. These are SOS signals from your AC compressor.

How Refrigerant Leaks Affect the Compressor

A refrigerant leak is like a runner with no shoes. It can keep going for a while, but eventually, it’s going to cause problems. If there’s not enough refrigerant, the compressor has to work harder to cool your home. This can cause it to overheat and shut down.


Overheating is a common cause of AC compressor failure. Just like you, your AC compressor can get too hot. When it does, it shuts down to protect itself.

Causes of Overheating

Several things can cause your AC compressor to overheat. Dirty coils can make it harder for heat to be released, causing the compressor to overheat. Low refrigerant levels can also cause overheating, as the compressor has to work harder to cool your home.

Effects of Overheating on the AC Compressor

When the AC compressor overheats, it shuts down to prevent damage. This is like its built-in self-defense mechanism. But if it keeps overheating, it can damage the compressor and prevent it from turning on.

Preventive Measures to Keep AC Compressor in Optimal Condition

Regular Maintenance

Regular maintenance is like going to the gym for your AC unit. It keeps it in shape and helps prevent problems. This includes cleaning or replacing the air filter, cleaning the coils, and having a professional service your unit annually.

Correct Thermostat Use

Using your thermostat correctly can help keep your AC compressor in good shape. Don’t crank down the temperature in an attempt to cool your home faster – it doesn’t work that way. Instead, set a comfortable temperature and leave it be. Constantly changing the temperature can put unnecessary strain on your compressor.

Prompt Repair of Electrical Issues

Electrical issues can cause serious damage to your AC unit if left unchecked. If you notice anything unusual – like your circuit breaker tripping frequently – call a professional to inspect your unit. It’s better to catch and repair these issues early before they cause more damage.

Early Detection of Refrigerant Leaks

Regular maintenance can help detect refrigerant leaks early. If you notice any signs of a refrigerant leak – like hissing noises, ice on the refrigerant lines, or your home not cooling properly – call a professional right away. A refrigerant leak can cause serious damage to your compressor if not fixed promptly.

Measures to Prevent Overheating

Preventing your AC compressor from overheating can save you from a costly repair or replacement. Keep your air filter clean, ensure your refrigerant levels are correct, and have your unit serviced regularly. If your unit is constantly tripping the circuit breaker, it might be overheating – call a professional to check it out.

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