What that sound means: a glossary for Gainesville air conditioners, sorted by how long you can wait
Air conditioners narrate their failures. Here is the vocabulary, with the Alachua County accents: acorns in the fan, lightning in the contactor, pine straw in the coil.
Shut it off now
These sounds mean damage is happening while the system runs. Turn it off at the thermostat and call, any hour.
Grinding or metal-on-metal scraping from the air handler. Blower motor bearings have failed or the wheel is hitting the housing. Running it chews the wheel and can seize the motor.
A loud hum with a click every few seconds, nothing starting. The compressor is trying to start and dropping out on its overload. A dead capacitor is the usual cause; each attempt heats the compressor further.
Screeching from the outdoor unit that rises and falls. High-pressure refrigerant forcing through a restriction, or a compressor in real distress. Rare, and not a wait-and-see sound.
A sharp crack or pop followed by a burning smell. An electrical fault at the contactor, the board or the strip heat. Off at the breaker, then call.
Call this week
The system can run, but the sound is a part on its way out, and in a Gainesville summer “on its way out” becomes “out” on the hottest Saturday.
A rattle from the condenser that comes and goes. On a lot under live oaks, the first guess is an acorn or twig through the top grille riding the fan. Second guess, a loose fan blade or motor mount; third, a cabinet panel screw backed out by years of vibration. Harmless for a day, blade-damaging over a month.
A hum from the condenser louder than it used to be. A weakening capacitor or a contactor with pitted contacts. Both are small, both are common after the summer lightning Alachua County gets, and both fail completely at an inconvenient time.
Squealing at start-up that fades after a minute. A blower belt on an old unit or a motor bearing beginning to dry. It is the grinding sound’s younger sibling.
Bubbling or gurgling at the air handler or in a wall. The condensate drain is partly blocked, usually by algae after a wet week. The next sound is silence when the float switch trips, and the sound after that is a ceiling stain.
Mention it at the tune-up
These are ordinary noises that still deserve a look twice a year.
Clicking from the attic in the evening. Duct and cabinet metal contracting after a 130-degree attic afternoon. Loose panels and unstrapped duct make it louder.
Whistling at a return grille. Air pulled through too small an opening or past a filter that is too dense. Common in 1970s ranches with one hallway return; it is also the sound of a blower working too hard.
A whoosh or thump when the system starts. Flex duct inflating, or a plenum panel flexing. Normal in moderation; a loud bang is a duct that has pulled loose.
Dripping or ticking near the air handler. Condensate hitting the pan or the drain. Healthy, unless it is landing somewhere it should not.
The Gainesville accents
The acorn rattle belongs to any yard under live oak, roughly half the city, and peaks in October and November. Pine straw packs coils in Blues Creek, Westchester and the Millhopper corridor and produces a laboring roar. The post-storm buzz, a contactor or capacitor hit by a nearby strike, is a July and August sound in the state with the most lightning in the country. And the student-rental screech, a blower run on one filter for two leases, arrives every August as the complexes along Archer Road refill.
What the visit sounds like
We listen with the system running, then with panels off. Capacitor and contactor get tested, not eyeballed; blower amperage and bearing play checked; duct straps tightened; the drain flushed. Parts for every sound in the first two sections ride on the Alachua County truck, priced before they go in, with no after-hours charge. And do not reach into a condenser with the power on, or assume a sound that stopped fixed itself: an acorn that worked free may have taken a chip of blade with it.
Noise questions from under the canopy
My outdoor unit started a hard rattle right after a windy night in Blues Creek. What fell in?
Usually an acorn or a twig through the top grille, bouncing off the fan. Shut the unit off, look down through the grille with a flashlight, and if you see debris, call rather than reach in. If the rattle persists with the fan clear, the blade or motor mount is loose.
The system buzzes but nothing starts after a thunderstorm. Is that the compressor?
More often it is the contactor, whose contacts a lightning surge can weld or pit, or a capacitor the surge finished off. Both are small parts we carry. A compressor that hums and trips is a different buzz, and we can tell them apart by amperage in a minute.
Is a gurgling sound in the wall of my Duckpond house the air conditioner?
Likely the condensate drain, which in a historic home runs through walls to the exterior. Gurgling means a partial clog, usually algae after a wet stretch, and it is the warning before a float switch trip or a ceiling stain. A drain flush is a quick fix.
New sound you can't place?
Record ten seconds of it and call. We'll tell you which column it's in.