What Causes The Outside AC Unit To Stop Working?

Some air conditioners, such as mini-split systems, have outside units. These outdoor components work by pulling warm air for the devices to convert into cold, comfortable indoor air. But sometimes these outside components can stop working. What could be the cause of these malfunctions? We researched for you to give you this answer.

Also called condensers, breakdowns or malfunctions to outside AC units can stem from different sources. Some of these origins are:

  • Fan motor failure
  • Insufficient power
  • Dirt buildup
  • Faulty capacitor

Understanding the source of the issue can help AC owners to use the correct solution to restore power to these appliances. Continue reading as we talk about air conditioner condensers and the reasons why they stop working in greater detail. We’ll also tackle some potential solutions to this issue in this post.

Home air conditioner unit in summer season, What Causes The Outside AC Unit To Stop Working?

What Do You Call The Part Of Air Conditioners That Is Put Outside?

HVAC technician removing a service panel on a mini-split ductless air conditioning system.

The outside component of an air conditioning system is the condenser. It generally works by converting warm outdoor air into cold indoor air. Some of the most important parts include:

  • Compressor: Houses the refrigerant and adds pressure to that substance. In turn, the coolant will cycle throughout the appliance.
  • Condenser coil: Takes the refrigerant in its gas form and alters it into a liquid state.
  • Evaporator: Often works with the condenser coil to revert the refrigerant to its gas form.
  • Fan: Blows heat away from the unit.
  • Expansion valve: Removes the pressure from the condenser to help limit the amount of refrigerant used.

Why Is My Outside Condenser Not Working?

Air Condition Service

The reasons for an air conditioner outside condenser to stop working typically vary for each owner. Some of the relatively common causes of AC condenser breakdowns are:

Fan Motor Failure

Significant stress to the condenser may cause the fan motor to break down. Condenser fans may also fail because of old age. It might be advisable to replace this part instead of attempting to repair it to avoid increasing the risks of harm brought to the system.

You can also read our post on the reasons why an air conditioner fan isn’t working to gain additional insight on this issue.


Insufficient power

Air conditioners need to draw sufficient power from a residence or commercial establishment’s main power supply to run as efficiently as possible. For example, the typical mini-split AC needs about 600 to 800 watts to provide comfortable cold air to connected spaces. Drawn energy that's less than the recommended amount may not provide sufficient power to make the outside condenser work.

Dirt Buildup

An outside AC condenser is susceptible to accumulating dust, dirt, and debris. Ideally, it’s best to clean this component at least twice per year. Property owners may also purchase condenser covers to help reduce filth buildup.

Read our post on how to clean a central air conditioner for details on that topic.

Check out this air conditioner condenser cover on Amazon.

Faulty Capacitor

An AC capacitor works similarly to a battery. Its job is to absorb and store energy from a connected power supply to help provide sufficient electricity to the fans. The capacitor also maintains an adequate power output to the system to ensure the appliance doesn’t get too much or too little electricity.

In turn, a broken or malfunctioning capacitor is generally the main cause of an outside air conditioner condenser to stop working. Additionally, this breakdown can originate from different sources, such as significant heat, physical damage, and/or dirt buildup.

Check out this replacement air conditioner condenser capacitor on Amazon.

What Do You Do When Your Outside AC Unit Stops Working?

Technician is checking air conditioner ,measuring equipment for filling air conditioners.

Calling for professional AC repair services is usually the best option to tackle difficult outside condenser repair and/or replacement operations. However, property owners may save on relatively expensive professional labor expenses by troubleshooting their outdoor units first.

Here are some ways to try to sort out an outside AC unit that broke down:

  • Ensure the AC switch is in the ‘on’ position. Some air conditioners have an emergency shut-off switch that might be operational, which can prevent the condenser from functioning.
  • Check the circuit breaker panel. A blown fuse from a recent thunderstorm or power surge may trip the switch connected to the AC.
  • The thermostat should be in its ‘cool’ mode. The air conditioner’s condenser should function properly when set to this mode.

If the above troubleshooting steps don’t restore power to the appliance, you may proceed with going through DIY repairs. But ensure that the method you use coincides with the source of the problem.

How To Replace An Air Condenser Fan Motor?

Air Conditioner compressor condenser coil with fan and tools being worked on next to a brick house for repair maintenance.

It’s advisable to check your owner’s manual before attempting to replace your AC condenser’s fan motor. Keep in mind that specific air conditioner types often use different fans. For example, central air conditioner condensers typically have different frameworks when compared to those used by mini-split systems, despite both models serving similar purposes.

Confirm if the air condenser fan motor is the reason for the breakdown by using a multimeter. This tool should show that the fan is receiving sufficient electricity for it to run. If not, the motor may need a replacement.

Check out this multimeter on Amazon.

Additionally, the replacement fan motor should match the model of the air condenser. Otherwise, compatibility issues may arise, causing more damage to the system.

After taking note of those precautions, here are the steps to help you replace an air condenser of a central AC to help you gain an idea on how to proceed with this task:

What You’ll Need

  • Screwdriver
  • Adjustable wrench

Step-by-Step Guide

  1. Remove the fuses from the disconnect box to disable the power running through the condenser unit.
  2. Take out the access panel by unscrewing it.
  3. Ensure that the capacitor has no charge by placing the metal end of a screwdriver on top of it to avoid electrocution.
  4. Remove the capacitor carefully.
  5. Unscrew the fan guard securing the fan and its motor to the condenser’s frame.
  6. Take a picture of the fan orientation to ensure a proper installation of the new component.
  7. Loosen the screw on the fan with the adjustable wrench. Then, pull the fan blade away from its frame.
  8. Unscrew and remove the fan motor from the fan guard.
  9. Remove the wires attached to the old fan motor.
  10. Install the new fan motor by doing the previous steps in reverse order.
  11. Restore power to the air conditioner and turn it on to test for persisting issues.

Watch the video below to learn additional details about this project:

How To Replace An AC Circuit Breaker?

A human hand is cutting out, turning OFF a circuit breaker fuse box switch.

Be careful when working with circuit breaker panels because you’re working with live electricity. Don’t attempt this job if you feel that you don’t have the confidence, knowledge, or skill to finish it properly.

If you wish to continue, ensure that you’re wearing safety equipment like goggles and a pair of non-conducting gloves. Also, make sure that you identify the switch connected to your air conditioner. Tinkering with other fuses might lead to unwanted power failures to some electronics in the area.

After finding the faulty switch for your AC, take note of the exact make and model of the component and purchase the same unit. To prevent uneven power delivery, don’t mix switches in your fuse box.

With the new AC switch in hand, you can continue with these steps:

Step-by-Step Guide

  1. Turn off the main power from the breaker panel and remove its covering.
  2. Apply adequate pressure to the top of the old switch to release it from its lock. Then, pull it from the circuit breaker panel.
  3. Unscrew but only loosen the screw on the switch.
  4. Remove the wires connected to the old switch.
  5. Connect the wires to the new switch and install it in the breaker panel.
  6. Return the cover to the panel and restore power to the mains.
  7. Test the air conditioner if its condenser is functioning as intended.

Take note that if a thunderstorm affected your AC's circuit breaker switch, chances are that other areas in the panel became deteriorated from the intense power surge. If so, the steps above may only provide you with a temporary solution, and replacing the entire panel may offer better long-term results.

How Much Does It Cost To Fix An AC Condenser?

Air conditioner owners should prepare to pay $900 to $2,800 for the repair or replace certain parts from their appliances’ condensers. Replacement costs are typically more expensive than the overhead demands of AC condenser repairs. Owners should expect to pay $1,300 to $4,000 to replace the entire unit.

Final Words

Horizontal shot of four air conditioning units outside of an upscale apartment complex.

Outside AC condenser units can malfunction or break down because of different reasons. Some of these causes may include (but aren’t limited to) fan motor failures, inadequate power, dust and dirt buildup, and faulty capacitors. Verify the source of the problem to use the correct solution and restore efficient serviceability to the cooling system.

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