Why Won’t the Outdoor AC Unit Turn On?

There are multiple explanations for why an outdoor AC unit may not be running while the indoor unit seems to be functioning fine. Believe it or not, this is a common HVAC issue that many other homeowners have encountered at some point in time.

Check if the outdoor AC unit was accidentally turned off by locating and flipping the on-off switch near the unit. This simple step can often resolve the issue.

One thing to remember about a split-system air conditioner is that it won’t operate properly if one of the units isn’t working. So if the outdoor unit won’t turn on and there seems to be nothing wrong with the indoor unit, it’s likely that air is still flowing. However, cooling a home will be impossible unless the outdoor unit is fixed.

This post discusses the most common reasons why outdoor AC units fail to work.

Damaged Fan Motor

The fan motor of an outdoor unit may burn out due to wear and tear. Typically, burnt-out fan motors can be detected during a regular inspection, so regular inspection and maintenance of the cooling system are essential. When cooling services such as maintenance and inspections are performed properly and regularly, problems of this type can be fixed early, avoiding more extensive and costly repairs.

Deficient Power Supply

If the fan assembly isn’t getting an adequate power supply, the outdoor fan will likely stop spinning. Diagnosing this type of issue can be difficult, so calling a skilled technician to find and resolve the problem is necessary.

Bad Capacitors

The role of capacitors is to store the energy needed by the air conditioner’s fans to function. A capacitor may be used to start the fan and keep it running. In some units, there are dual capacitors to power both the air conditioner’s fans and the compressor. 

Similar to ordinary batteries, capacitors can lose their ability to store energy over time. They can be damaged by power surges, high voltage, and high temperatures. When the capacitor goes bad, it won’t be able to power the air conditioner’s fan, which means the fan won’t be able to spin, so no air will come out of the vents.

If no air is being released through the vents, calling an AC technician to confirm the source of the problem is advisable. However, to test it further before calling in an expert, try this:

Slide a long wooden stick through the grate, protecting the air conditioner’s fan. Ensure the stick is sturdy and slender enough to fit. Then, gently push one of the fan blades to get it spinning. Never use fingers or any conductive metal to spin the fan.

If the fan takes off and continues spinning after pushing the blade, the start capacitor is likely broken. In this case, call a professional to have the capacitor replaced. An air conditioner with a poor capacitor will make the fan motor work much harder, causing the motor to burn out more quickly. Furthermore, in the case of a dual capacitor, a faulty capacitor can cause the compressor to overheat, resulting in further damage to the air conditioner.

If the fan won’t spin after pushing one of the blades, it’s possible that either the fan motor itself is damaged, the fan motor bearings are jammed, or dirt or debris has accumulated around the fan axle.

Issues with the Contactor

The contactor is in charge of controlling the fan motor, so if the contactor develops problems, the outdoor fan might stop spinning. Detecting contactor problems may not be easy, so calling an expert in HVAC repairs and installations is recommended.

Quick Troubleshooting Tips

Check if the Unit Was Accidentally Turned Off

Sometimes, the problem with an outdoor AC unit can be as simple as being accidentally turned off. This can be easily fixed by switching it back on. Outdoor fans usually have an on-off switch in a small box by the unit, so checking this first is essential.

Search for a Tripped Circuit Breaker or Blown Fuse

A blown fuse or a tripped circuit breaker is often caused by a power surge. To check if either of these is the problem, look for the fuse box if the home is older or the circuit panel if the house is newer. If there is a fuse box, check for a blown fuse; if there is a circuit panel, look for a tripped circuit breaker. In the case of a tripped circuit breaker, try flipping it off and then back on.

Alternatively, check if the air conditioner has a fuse at the safety shutoff box. Try to replace the fuse even though there’s no sign of a blown fuse.

If any of these methods solve the problem but the issue occurs again later on, the air conditioner might be pulling too much electricity, overheating, or short circuiting. Make sure to call an HVAC technician to take a look at the problem.

Check the Thermostat Settings

Make sure that the thermostat is set to “cool,” and its temperature is set lower than what is believed to be the room’s temperature. If something is wrong with the thermostat and the indoor unit is still running, the indoor unit is likely to be the problem.

Fix My Air DFW of Fort Worth specializes in residential and commercial HVAC services, including routine maintenance, installation, and repair. All makes/models. Call us at (817)839-3511.