Why Is My Outdoor AC Unit’s Fan Not Spinning? A Phoenix Tech Explains.

Has your AC stopped blowing cold air? Maybe you’ve already researched why your AC is blowing hot air and can’t find the culprit. Now what?

Go to your air conditioner’s outdoor unit and check that the compressor is working and the fan is spinning. The compressor is the heart of a central AC system and lives in an airtight seal in the outdoor unit. When it doesn’t work properly, the system can’t cool your home.

You can tell if the compressor isn’t working if:

• The AC isn’t cooling as well as it used to
• You hear loud or odd noises from the outdoor unit
• You don’t hear the compressor humming at all

In any of the above apply, two scenarios could explain a deeper problem with your air conditioner:

Let’s explore both scenarios' impact on your air conditioner’s performance, along with the next steps you should take.

When the AC system’s compressor works but the fan doesn’t spin, you have a broken fan motor caused by a bad start capacitor on your hands.

The start capacitor is an electric device similar to a large battery in your outdoor unit. It starts up the system by providing a jolt of stored energy to the electric motor. A capacitor’s extra juice is vital since the system uses 3x the power it needs to function at startup. Without a functional capacitor, the fan won’t be able to start.

Signs of a bad capacitor include:

• Hearing your air conditioner being louder/noisier than normal
• Hearing stuttering or clicking sounds, then the AC shuts off
• Hearing your AC hum and buzz but not turn on
• Hearing your AC click but not turn on
• Seeing the bottom or top of the capacitor is bulging
• Seeing visible gooey discharge on the capacitor

Two short-term solutions can get your fan going long enough for your AC to cool your home again. However, you should still contact a professional HVAC technician to make sure the capacitor is fully functioning. Otherwise, you may risk damaging the compressor by overheating it, and replacing a compressor can cost as much as a full system replacement.

First, take a long, thin object like a stick or screwdriver and gently prod the fan blades to see if you can get it going. Do not use your fingers. This should provide some kick for the fan motor to get up to speed.

If that doesn’t work, you can attempt a hard start kit or have a technician do so for you. It’s similar to jumping cables for a dead car battery. This kit acts as a substitute capacitor to provide enough juice to start up your compressor.

When both the compressor and fan aren’t working, either no power is getting to the outdoor AC unit, or there is a defective compressor contactor. Let’s look at how you can inspect your air conditioner and electrical system to find the true problem.

First, check your main electrical control panel to see if any power goes to the air conditioner. If the air conditioner’s breaker is in a “middle” position, it tripped. The system tried to use more amps than the breaker could handle, so the breaker shut it off to protect your home from an electrical current overload.

To reset the breaker, turn off your AC at your thermostat. Then, turn the breaker off and on. Wait 30 minutes, then turn the AC back on. Do NOT reset the AC breaker again if it trips again. Another trip indicates a deeper electrical problem, and you should contact a professional immediately.

Now, what if the breaker hasn’t tripped? The contactor may be defective and need replacement. This contactor plays an important role as a relay between the thermostat, compressor, and fan motor that turns the outdoor unit on and off. Once you turn on your AC at the thermostat, the contactor tells the compressor to turn on. A bad contactor won’t be able to “relay” the signal.

Signs of a faulty contactor typically include strange noises from the outdoor unit. Or if you hear the air conditioner click but without turning on. You’ll want to call a technician to inspect your contactor and thermostat for issues.