Why is my AC unit working inside but not outside?

Author: Dorian Reichel  |  Last update: Thursday, October 9, 2025

The outside unit may not run if it's shut off or the safety switch is engaged. Worn parts, like fan motors or contactors, can prevent the unit from turning on. Debris inside or outside of an AC unit can keep it from running properly. If a bad compressor is to blame, you'll need to install a new cooling system.

Why is my AC unit running inside but not outside?

If your inside unit is running but the outside AC unit fan isn't running, there could be a few potential causes. To diagnose the problem, first, check the circuit breaker, then inspect the condensing unit for any visible damage, and then check if the fan's airflow is blocked.

Why is my AC unit not kicking on the outside?

Make sure the outside unit is turned on (there's probably a switch near the unit). If the outside unit has a separate circuit breaker, check your circuit box and make sure it hasn't been tripped. A more serious issue if the outside air conditioning unit's not working is a broken compressor, capacitor or fan.

Why is the outdoor of an AC unit not working?

If your outside AC unit is not turning on, it could be a thermostat issue. If your thermostat clicks but the AC does not turn on, you could have an issue with the thermostat itself. Broken thermostats often fail to properly communicate with the rest of your heating and cooling system.

Why wont my AC unit turn on outside?

Look for a Tripped Breaker

If your AC won't turn on, you can check two places for a circuit breaker or electrical panel. Older homes have a main electrical panel on the outside of the home or a circuit panel on newer homes. Check the electrical panel to see if the breaker is tripped. Reset it if it is.

Outdoor AC Unit Not Running, Not Turning On! Top 10 Problems!

How do I reset my outside AC unit?

In AC systems, the air conditioner reset button is on the outside unit's lower edge, typically close to the ground. Some models have the reset button located behind the service panel, which may require tools to remove. Reset buttons are usually red or yellow with a clear “reset” label.

How do I know if my outside AC fuse is blown?

If you think your air conditioner has blown a fuse, the first sign you'll notice is that the outside AC unit is inoperable. The best way to check for a blown fuse is by using a voltmeter. Be warned — you are working with live electricity and should use extreme caution when troubleshooting your system.

How do I get my outside AC unit to kick on?

Outside AC Unit Won't Turn On? What to Do Before Calling for Repairs
  1. Make sure the thermostat is set to COOL. ...
  2. Check the emergency or shut-off switch. ...
  3. Check the inside unit's power switch. ...
  4. Look for a blown fuse or tripped circuit breaker. ...
  5. Look for problems with your condensate drain line. ...
  6. Try resetting the air conditioner.

Why is the outside fan not working?

Let's start with the obvious – if your outdoor fan isn't getting ANY power at all, well…it's not going to spin! A tripped circuit breaker or blown fuse cutting electricity could easily be why that fan motor hasn't engaged. Loose or corroded wiring connections to the unit are another power problem to investigate.

How to tell if an AC capacitor is bad?

A sure sign of a bad AC capacitor is a humming sound from within the access panel. Any humming noises indicate a problem with the air conditioning system or the components of the AC unit. Try turning the power on and off again to see if it was a one-time issue with the motor or a recurring problem.

Is there a fuse on the outside AC unit?

The AC fuse on most HVAC systems is typically on the unit's control board. You'll normally find the board behind an access panel on the unit's lower compartment. While you sometimes have to unscrew areas to access the control board, others have clips.

Why is my outside AC unit not cooling?

If your AC is running but not cooling, it could be due to a dirty air filter, incorrect thermostat settings, a malfunctioning thermostat, a refrigerant leak, dirty condenser coils, blocked vents or ducts, a faulty compressor, frozen evaporator coils, or electrical issues.

Can the AC run without the outside unit running?

A central AC system consists of indoor and outdoor units. An indoor air handler can continue running when the outside unit has shut down. While air will blow from the vents, it won't be cooled; it may be as warm as the summer air outside.

How to check if an AC condenser is working outside?

No Sound Coming From The Condenser

Listen if sounds are coming from your outdoor unit. It is a sign that it isn't working as it should if you don't hear any sound. Some air conditioners are designed to be quiet, but you should still hear a low hum.

How much to replace an AC capacitor?

Replacing an AC capacitor costs $180 on average, including the price of the capacitor plus the cost of labor to install it. However, the total price you pay could be as low as $200 or as high as $400, depending on the type of AC capacitor and the complexity of replacing it for your particular system.

Should the outside fan run when AC is on?

The short answer: Definitely not. (Unless you have manually engaged your outside fan to run constantly, but it shouldn't be running for hours on it's own.) If your HVAC is functioning correctly, it should keep your house cool by cycling on for 15-20 minutes at a time—with distinct pauses in between each cycle.

Why is my outside AC not turning on?

To fix this issue, you will need to reset the circuit breaker by switching it off and then back on again. If this doesn't work, then you may need to check for any loose or corroded wiring connections, replace any faulty fuses or circuit breakers, and ensure that your AC system is getting enough power supply.

What happens if an outdoor fan is not working?

If the compressor is working, but the fan won't turn, then the problem is most likely with the motor and/or capacitor. When an AC fan is not spinning and no audible indications of compressor activity are detected, it is usually due to a lack of power or a malfunctioning compressor contactor.

How do I reset my outside AC fan?

Resetting your AC unit usually involves turning off the power, waiting for a specific duration, and then turning it back on. This process can vary slightly depending on the make and model of your unit. Typically, you'll find a reset button on the outdoor unit. Press and hold it for a few seconds.

Why is my AC running in the house but not outside?

When the outside unit breaks down but the inside unit is running, the culprit may well be a broken compressor in the outside unit. That's typically a major repair, something that might even warrant a system replacement.

Do all outside AC units have a reset button?

Not all air conditioning units have a reset button, but if yours does, it's typically located on the outdoor unit. Here's how to locate it: Turn Off the Power: Before you search for the reset button, ensure the power to the unit is turned off for safety reasons.

Why is the fan on my outside AC unit not running?

In short, common issues that can cause an air conditioning unit fan to stop spinning are electrical issues, problems with the capacitor, contactor issues, a burnt out air conditioner motor, a broken fan belt, or clogged air filter.

How do I reset an outside AC breaker?

After finding the circuit breaker for your AC unit, flip it to the off position. Leave it off for around 30 minutes, then flip it back to the on position. If you have fuses, you can only reset the AC by taking the fuse out.

How much does it cost to replace a fuse in an AC unit?

AC Fuse, Circuit Breaker, or Relay Replacement Cost

Expect to pay between $15 and $300 to have AC fuse and circuit breaker issues addressed or relays in your AC unit replaced. These projects do not usually take more than a couple of hours.

What is the lifespan of an AC fuse?

Wear and Tear on the Fuse

The lifespan of a fuse can be up to 20 years. AC fuses are usually what is known as 'slo-blow' or 'time delay' fuses. This means that they are at work every time you turn the machine on and off and eventually, will simply wear out due to the strain of the operation.

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