AC Troubleshooting Guide
Common AC problems, what to check, and when to call a professional.
From our technician, Selim Reza:
"Before you call anyone, there are simple things you can check yourself. I've put together this guide to help you troubleshoot common AC problems. Some issues have easy fixes. But if you're ever unsure or the problem persists, don't hesitate to call — it's always better to catch a small issue before it becomes an expensive one."
AC Not Turning On
Your AC won't start at all — no sounds, no airflow, nothing happens when you adjust the thermostat.
🔎 What to Check:
Make sure it's set to COOL (not HEAT or OFF) and the temperature is set below the current room temperature. Replace batteries if it's a battery-powered thermostat.
Go to your electrical panel and look for the AC breaker. If it's tripped (in the middle position), switch it fully OFF first, then back ON. Note: if it trips again immediately, stop and call a technician — there may be an electrical issue.
A severely clogged filter can cause the system to shut down as a safety measure. Remove the filter and see if the system starts. If it does, replace the filter immediately.
Many Florida AC systems have a float switch on the drain line. If the drain is clogged and water backs up, the float switch shuts down the system to prevent water damage. Look for standing water in the drain pan.
📞 When to Call a Professional:
If the breaker keeps tripping, or if thermostat and filter checks don't help, the issue may be a faulty capacitor, contactor, control board, or wiring problem. These require professional diagnosis.
Call (786) 447-4810AC Running But Not Cooling
The system runs and you hear the fan, but the air from the vents isn't cold — or it's barely cool.
🔎 What to Check:
The #1 cause of poor cooling. A dirty filter restricts airflow over the evaporator coil, reducing its ability to absorb heat. Check and replace it if it looks dirty or clogged.
Go outside and check if the condenser fan is spinning. Clear any debris (leaves, grass, dirt) around the unit — it needs at least 2 feet of clearance on all sides for proper airflow.
Check the copper refrigerant lines going to the outdoor unit. If you see ice or frost, your system may have low refrigerant or poor airflow. Turn the system OFF and let the ice melt before calling a technician.
Make sure all supply vents are open and unblocked by furniture, rugs, or curtains. Closed vents cause pressure imbalances that reduce system efficiency.
📞 When to Call a Professional:
If changing the filter doesn't help, or if you see ice on the lines, you likely need a professional to check refrigerant levels, test the compressor, and inspect the coils. Low refrigerant means there's a leak that needs to be found and repaired.
Call (786) 447-4810Strange Noises from AC Unit
Your AC is making unusual sounds — buzzing, rattling, clicking, squealing, or banging.
🔎 What Each Sound Means:
⚡ Buzzing
Often electrical: failing contactor, bad capacitor, or loose wiring. Could also be a malfunctioning compressor.
🔨 Rattling
Loose screws, debris in the outdoor unit, or a loose fan blade. Check for visible debris you can safely remove.
🔘 Clicking
Normal at startup/shutdown. Constant clicking suggests a relay or control board problem.
🎵 Squealing
Belt slipping or motor bearing failure. The motor may need replacement soon.
💨 Hissing
Possible refrigerant leak. Turn off the system and call a technician immediately.
💥 Banging
Loose or broken internal component — possibly a connecting rod, piston pin, or crankshaft. Turn off and call a technician.
📞 When to Call a Professional:
Any loud, persistent, or new noise warrants a call. Hissing and banging sounds should be addressed immediately. Turn off the system to prevent further damage while you wait for service.
Call (786) 447-4810Water Leaking from AC
You notice water dripping from the indoor unit, pooling around the air handler, or water stains on the ceiling.
🔎 What to Check:
In Florida's humidity, the drain line clogs frequently with algae and mold. Find the drain line outside (usually a PVC pipe near the outdoor unit). Try pouring a cup of distilled white vinegar down the line's access point. If you have a wet/dry vacuum, you can try suctioning the clog from the outside end.
A clogged filter can cause the evaporator coil to freeze. When the ice melts, it overflows the drain pan. Replace the filter and let the system run on FAN ONLY mode until any ice melts.
Older systems may have a cracked or rusted drain pan. Look for visible damage. If the primary pan is overflowing into the secondary pan, the drain is likely clogged.
📞 When to Call a Professional:
If the vinegar flush doesn't work, the drain line may need professional clearing. If you see ice on the coil, have the system checked for low refrigerant. Water leaks should be addressed quickly to prevent mold growth and ceiling/wall damage.
Call (786) 447-4810AC Short Cycling (Turns On and Off Frequently)
Your AC turns on for a few minutes, shuts off, then turns on again quickly. It never completes a full cooling cycle.
🔎 What to Check:
Short cycling's most common DIY fix. A dirty filter causes the evaporator to freeze, triggering the system to shut down. Once the ice melts slightly, it restarts — creating a short cycle.
If the thermostat is near a window, door, heat source, or in direct sunlight, it may read incorrect temperatures. This can cause the system to cycle on and off based on false readings.
Make sure return air vents aren't blocked by furniture or closed. Restricted return air causes pressure problems that can trigger safety shutdowns.
📞 When to Call a Professional:
If filter replacement doesn't solve it, the system may have low refrigerant, a failing compressor, or an electrical issue (bad capacitor or contactor). An oversized AC unit can also cause chronic short cycling — this requires professional evaluation.
Call (786) 447-4810Unusually High Electric Bills
Your FPL bill has jumped significantly, and the AC seems to be running constantly.
🔎 What to Check:
A dirty filter makes the system work 15-25% harder to push air. This translates directly to higher electric bills. Replace it every 1-3 months in Florida.
Setting your thermostat to 72°F or below in South Florida means the system runs almost constantly. Try setting it to 76-78°F — each degree higher saves about 3% on cooling costs.
If you can access your ductwork (attic or crawlspace), feel for air leaking at joints and connections. Duct leaks can waste 20-30% of your cooled air.
Use a garden hose (not pressure washer) to gently wash dirt and debris off the condenser coils on the outdoor unit. Dirty coils reduce efficiency significantly.
📞 When to Call a Professional:
If your bills stay high after these checks, the system may need a professional coil cleaning, refrigerant check, or efficiency evaluation. If your system is 10+ years old, it may be losing efficiency and worth evaluating for replacement. We can assess this honestly.
Call (786) 447-4810Bad Odors Coming from AC
There's a musty, moldy, burning, or chemical smell when the AC runs.
🔎 What Each Smell Means:
🦠 Musty / Moldy
Mold or mildew in ductwork, drain pan, or on the evaporator coil. Very common in Florida. Coil cleaning and drain treatment usually helps.
🔥 Burning
Turn off system immediately. Could be an overheating motor, electrical short, or burning wire insulation. Call a technician before running the system again.
🧬 Rotten Eggs
Possibly a dead animal in the ductwork. This requires duct inspection and cleaning by a professional.
🧪 Chemical / Sweet
Could indicate a refrigerant leak. Refrigerant is harmful to breathe. Turn off the system and ventilate the area. Call immediately.
📞 When to Call a Professional:
Burning and chemical smells should be addressed immediately — turn off the system first. Musty smells benefit from professional coil cleaning and drain treatment. Don't ignore persistent odors as they can indicate health hazards.
Call (786) 447-4810Simple Maintenance Tips for South Florida
Change Filters Monthly
In Florida's dusty, humid climate, monthly filter changes keep your system running efficiently. Set a phone reminder.
Pour Vinegar in Drain Line
Once a month, pour 1 cup of distilled white vinegar down the condensate drain access point to prevent clogs and mold growth.
Keep Outdoor Unit Clear
Maintain 2 feet of clearance around the outdoor condenser. Trim bushes, clear leaves, and rinse coils with a gentle hose spray quarterly.