Hey It’s Mark Again 👋
There’s nothing like flipping the breaker on your brand-new Goodman GLXS4BA3610 condenser… and hearing nothing. Or worse—a loud, angry buzz that makes you rethink your life choices.
Whether you just wrapped the install or your outdoor unit's been running fine for weeks, these types of electrical issues are super common. And don’t worry—most of them aren’t as scary as they sound. Today, I’m walking you through how to diagnose and fix buzzing, humming, or dead outdoor units, and we’re using the GLXS4BA3610 as our case study.
Grab your multimeter, a screwdriver, and maybe a cold one for later. We’re going in. ⚡🔍
First Question: What Do You Hear (or Not Hear)? 🧠👂
Let’s start simple. Sound tells you a lot.
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Buzzing or humming but no fan movement? Probably a capacitor.
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Clicking from inside but no compressor start? Could be a relay or contactor.
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Totally silent? You might have a power or low-voltage control issue.
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Fan runs but compressor doesn’t? Welcome to capacitor town… or worse, compressor failure.
This isn’t guesswork. It’s pattern recognition. HVAC School has a great primer on the sounds of electrical failure if you want to geek out further.
Step 1: Is It Getting Power? 🔌
A. Check the Disconnect Box
Make sure the outdoor unit is getting high voltage (208–230V) from the disconnect. Pull the handle and inspect the fuses. You’d be surprised how often it’s just a blown fuse or tripped breaker.
Use your multimeter across L1 and L2 at the contactor terminals. You should read around 240V.
⚠️ Safety tip: If you're not comfortable checking live voltage, stop here and call someone who is. This stuff bites.
B. Breaker Panel Check
Double-check your breaker inside. A tripped breaker might look on, but feel loose or half-clicked. Flip it all the way off and back on.
For best practices, Family Handyman has a solid breakdown on breaker issues tied to outdoor AC units.
Step 2: Low Voltage (24V) Control Circuit – The Invisible Culprit
You need 24V coming from the thermostat to trigger the contactor. No 24V? The contactor won’t close. The compressor and fan won’t run. End of story.
Here’s how to check it:
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Go to the contactor coil and measure voltage between the two low-voltage terminals.
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You should see 24V when the thermostat is calling for cooling.
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No 24V? Go upstream:
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Float switch tripped?
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Blown fuse on the air handler board?
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Broken wire?
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Transformer cooked?
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You can read more about tracing low-voltage AC issues in HVAC Software's electrical troubleshooting guide. It’s worth bookmarking.
Step 3: The Contactor – Click, Stick, or Dead
The contactor is that little black box with a plunger in the center. It’s a relay that closes the high-voltage circuit when it gets the 24V signal. But over time? It sticks. It melts. It dies.
What to look for:
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Burnt or pitted contacts – replace it.
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Plunger not pulling in? No 24V or bad coil.
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Buzzing? May be partially engaging or vibrating from weak voltage.
This one’s usually cheap to replace. I keep a box of spares in my truck. It’s a top failure point for a reason.
Step 4: The Capacitor – The Classic Troublemaker 🎯
If you hear a hum but the fan or compressor doesn’t spin, this is your #1 suspect.
The GLXS4BA3610 uses a dual-run capacitor to start both the fan and compressor. When it dies:
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Fan may try to spin but won’t start
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Compressor may buzz then shut off
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Unit may overheat or trip breaker
To check it:
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Turn off all power.
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Discharge the cap with a resistor or screwdriver (carefully).
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Remove wires and test µF (microfarads) across terminals.
Compare your reading to the rating on the label (usually something like 45+5 µF ±6%). If it’s more than 10% off, swap it. If it’s bulging like a can of soda in the freezer—definitely swap it.
For visual learners, This Old House has a great walkthrough on replacing AC capacitors.
Step 5: The Fan Motor – Spin or No Spin?
Let’s say the compressor runs but the condenser fan won’t start. Could be:
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Bad capacitor
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Stuck fan motor bearing
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Blown motor winding
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Bad start relay or internal overload
Try giving the fan blade a gentle nudge with a stick (never your hand). If it spins up, it’s probably just a bad cap. If it doesn’t? Motor’s toast.
Also, check for voltage at the motor terminals. If you’ve got 240V and no movement, you’re replacing that motor.
Step 6: Compressor Buzzes but Won’t Start – The Heartache Begins 😬
This is the sound no tech wants to hear. Your compressor is energized but not running. Could be:
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Hard start needed (add a start assist kit)
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Open windings
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Locked rotor
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Internal overload trip
You’ll want to ohm out the windings between common/start/run. A locked rotor amps (LRA) test with a clamp meter will tell you if the compressor’s trying but failing.
Bonus Tip: Don’t Ignore the Thermostat
Sometimes the issue starts before the outdoor unit even gets a signal.
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Is the thermostat wired correctly?
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Does it have batteries?
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Is the “Cool” mode actually calling?
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Is the wiring loose at the air handler?
A bad thermostat or loose common wire can take your 24V signal offline—leaving you chasing ghosts outside.
Real-World Example: The Mystery Buzz That Wasn’t the Compressor
Last summer, I had a GLXS4BA3610 unit that buzzed like a beehive. Everyone swore it was the compressor. Turns out? The contactor coil was receiving 16V due to a half-failed transformer. It was just enough to partially engage, causing the plunger to vibrate—but not fully close.
Swapped the transformer, and boom—unit ran smooth as butter.
Moral of the story? Always check your voltages, don’t assume the loudest part is the broken one.
Final Thoughts from Mark 🔦
If your Goodman GLXS4BA3610 outdoor unit is acting up—buzzing, humming, or just plain silent—it’s probably not the end of the world. Nine times out of ten, it’s something small but critical: a bad cap, a lazy contactor, or a blown fuse.
Take your time. Listen for the clues. Use your meter. And if you’re stuck in the diagnosis phase and thinking, “maybe I should’ve just replaced the whole thing…”—don’t worry. If you do need a new system (or parts), you can grab the full Goodman setup over at The Furnace Outlet.
Dealing with high pressure? Visit: Here’s How to Check R-32 Charge on a Goodman 3 Ton 14.5 SEER2 System Without Guesswork.
It’s a solid R-32 system that delivers the goods—if you respect the wiring. 😉
Catch you on the next one. Stay grounded out there. 🔧⚡
- Mark, your go-to HVAC tech
