Outside AC Compressor Not Turning On: 5 Proven Solutions

Outside AC compressor not turning on? In this article, we’ll look at the common reasons for this issue and how to troubleshoot it.

Outside AC Compressor Not Turning On
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How to Troubleshoot Outside AC Compressor Not Turning On

Let’s dive right into how you can resolve this problem. Later in the article, we’ll reveal the causes responsible for your outside AC compressor not turning on.

Checking the Thermostat

Start with the easy stuff. Check the thermostat settings and replace the batteries if needed. If that doesn’t work, you might need to replace the thermostat.

Inspecting for Electrical Issues

Look at your breaker panel and AC fuse box for any tripped breakers or blown fuses. Also, inspect your AC for any visible wiring damage. But remember, safety first! Don’t try to fix electrical issues on your own.

Checking for Overheating

If your AC unit is hot to the touch, it could be overheating. Clean your condenser coils and call a professional to check the refrigerant levels.

Inspecting the Motor

If you smell a strong electrical odor from your AC, you could have a burnt-out motor. This requires a professional’s help.

Examining the Compressor Start Relay

If you’ve checked everything else and your compressor still won’t turn on, it might be the compressor start relay. You’ll need a professional to test and replace it if necessary.


When to Call a Professional HVAC Technician

While some of the issues can be fixed without the need of a professional, some other issues require professional help. Here are some of such instances:

Persistent Compressor Issues

If you’ve tried troubleshooting and your compressor still won’t turn on, it’s time to call a professional. They have the tools and knowledge to accurately diagnose and fix your AC.

Electrical Problems That Require Professional Attention

Remember, electricity is dangerous. If you suspect electrical problems, don’t try to fix them on your own. Call a professional HVAC technician.

Motor Replacement

If your compressor motor is burnt out, you’ll need a professional to replace it. Don’t try to do this yourself, as it can be dangerous and void your warranty.


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Common Reasons Why an Outside AC Compressor Isn’t Turning On

Just as we promised, the following are the common reasons why your outside AC compressor isn’t turning on.

Thermostat Issues

Sometimes, the culprit is as simple as a thermostat issue. Incorrect thermostat settings or a faulty thermostat are the common issues associated with your AC thermostat.

Electrical Problems

Electrical issues are another common reason for a compressor that won’t turn on. Here are three electrical problems that could be to blame

1. Tripped Circuit Breaker: A power surge or an overloaded circuit can trip the breaker, cutting power to your AC unit.

2. Blown Fuse: If your AC has a fuse box, a blown fuse could be the issue.

3. Damaged Wires: Wear and tear or rodent damage can cause wiring issues in your AC unit.


An overheating compressor can shut down to protect itself. Here are two common causes of overheating:

1. Dirty Condenser Coils: Your condenser coils, located in the outside unit, can get dirty over time, making it harder for your AC to release heat. This can cause the compressor to overheat and shut down.

2. Lack of Refrigerant: If your AC is low on refrigerant, it can’t effectively cool your home, and the compressor can overheat.

Motor Failure

Just like your car, your AC has a motor that can fail over time. Here are a couple of things that can go wrong:

1. Burnt Out Compressor Motor: If you’re smelling a strong electrical odor from your AC, you might have a burnt-out compressor motor.

2. Capacitor Issues: The capacitor gives your compressor motor the boost it needs to start up. If it’s faulty, your compressor won’t turn on.

Issues with the Compressor Start Relay

The compressor start relay, like the capacitor, helps your compressor start up. If it’s faulty, your compressor won’t turn on.


Preventative Measures to Avoid AC Compressor Issues

What can you do to prevent this issue from reoccurring? Here are a few tips:

Regular AC Maintenance

Regular maintenance is key to keeping your AC running smoothly. This includes cleaning your condenser coils, replacing filters, and getting a professional check-up at least once a year. It’s a small price to pay for a comfy, cool home, don’t you think?

Keep an eye on your thermostat settings. Ensure it’s set to “cool” and the desired temperature is lower than the room temperature. A simple tweak here can save you a whole lot of hassle.

Keeping Condenser Coils Clean

Your condenser coils can easily get dirty, causing your compressor to overheat. Make a habit of cleaning them regularly to keep your AC running efficiently.

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