How to Lower a Sub-Zero Refrigerator's Noise Level

The sounds a healthy refrigerator makes

Before chasing a noise, it pays to know the everyday sounds of a working unit, because a good share of noise worries turn out to be perfectly healthy behavior. A Sub-Zero built-in, like most modern refrigerators, runs its compressor in cycles rather than nonstop, moves cold air with small fans, and pushes refrigerant through narrow tubing that gurgles or hisses as pressure evens out after each run. Plastic liners, shelves and drawers grow and shrink slightly as the cabinet cools and the defrost system warms things up, which shows up as soft ticks and pops. Units with two separate cooling systems may start the freezer side a few minutes after the fresh food side goes quiet, so the sound can seem to move around the cabinet. If you are asking why your refrigerator is humming, a low, even hum that fades on its own is the compressor working as designed.

• a steady low hum from the compressor that ends without help
• a soft whoosh of air while the fans are running
• gurgling, trickling or a brief hiss as refrigerant settles after a cycle
• light ticks and pops as liners and shelves change temperature
• a short buzz, then a clatter, when the ice maker refills and drops cubes

Noises that point to a real fault

Fault noises have a different character: they are harsher, they show up at the wrong moment, or they simply never stop. A fan that ticks, chirps or grinds usually has a dry bearing or a blade brushing against frost or a loose cover, and in the freezer that often means ice has crept into the fan housing. A compressor that runs for hours without resting is working too hard, whether from a clogged condenser, a door gasket that no longer seals, or a problem inside the cooling system itself. A loud knock as the motor starts or stops can mean the compressor or a tube has shifted until it touches the cabinet. A water valve that buzzes for a long stretch with no ice being made, or chatters every few minutes, is struggling to open or close. To tell a fan from a compressor by ear, our fan motor and compressor guide walks through the difference.

• grinding, scraping or chirping from inside the freezer or behind the grille
• a compressor that never seems to rest while the cabinet feels warmer than usual
• a sharp bang or knock each time the motor starts or stops
• a valve that buzzes with no water flowing, or hums long after the fill is done

Level the cabinet and silence the rattles

Most vibration complaints have nothing to do with a failing part. A built-in refrigerator is heavy, and if it is carrying its weight on three supports instead of four, the compressor's ordinary pulse rocks it just enough to buzz against cabinetry, side panels or the edge of a countertop. Open the doors and lay a level across the top of the opening, then front to back on a shelf; the unit should read level side to side and should not rock when you press gently on a corner. Reaching the adjusters on a full-size built-in usually means taking off the lower grille or kickplate, and because these cabinets are tall and very heavy, it is wiser to get help, or have a technician do it, than to risk tipping one. Then go looking for the small rattles that add up, starting with the door bins and drawers.

• bottles and jars clinking against each other in the door shelves
• a crisper drawer or glass shelf that has slipped off its track
• a loose grille, kickplate or trim panel screw
• anything stored on top of an undercounter unit or wedged beside it

Clean the condenser so the compressor can rest

A dirty condenser is the most common reason a refrigerator gets louder over the years, because heat that cannot escape keeps the compressor and condenser fan running longer and harder than they should. On the Classic (CL), Sub-Zero places the condenser behind the flip-up grille; on the Designer (DET, DEC), it sits behind the kickplate, which two screws hold in place. Power it down from the touch panel first, wear a pair of work gloves, and draw a soft-bristled vacuum nozzle along the coils in line with the fins so none of them bend. Sub-Zero notes that a unit under 6 months old does not need this cleaning yet. An EC50 code paired with a flashing Service light means the control thinks the compressor has been running too much. If the food is still holding close to its usual temperature, a condenser cleaning is the first move, after which pressing the bell button, which doubles as the door ajar alarm, for 15 seconds wipes the code away. A cabinet that has already turned warm is past that point and needs a technician. If you would rather keep this on a schedule, a preventive maintenance and tune-up visit is one way to have it done.

Ice maker and water valve sounds

The ice maker accounts for a large share of the sounds people ask about, and most of them are normal. Each cycle the water valve opens with a short buzz, water trickles into the mold, and a while later the finished cubes fall into the bin with a clatter that can sound startling in a sleeping house. On Classic (CL), Designer (DET, DEC) and PRO Series units, the Max ice setting raises ice production by up to 30% for a 24-hour period, and Sub-Zero points out that some parts run faster during that window with a sound you will notice; if the kitchen seems busier after a weekend of guests, check whether Max ice is still on. If you rarely use ice, switching the ice maker off removes both the fill buzz and the nightly clatter. Much of the water piped into Encinitas homes is imported and on the hard side, and over time those minerals can partly block the inlet valve screen or stop the valve from closing cleanly, turning a brief buzz into a long drone. A valve that hums with no water moving, or water that keeps trickling after the fill, is a job for our ice maker and water valve repairs service.

Undercounter units and open kitchens

Undercounter refrigerators, wine storage and refrigerator drawers often seem louder than a tall built-in, not because they produce more sound but because the compressor and fan sit at knee height, close to where people sit and talk, inside a snug cabinet that bounces sound back into the room. These units breathe through the grille at the toe kick, so a rug edge, a pet bed or a recycling bin parked in front of it makes the fan and compressor run longer and harder. Keep that grille clear and vacuumed, make sure the unit does not touch the cabinet sides or the countertop above it, and confirm it sits firmly on the floor. In an open-plan kitchen, any refrigerator is loudest right after a door has been held open, because the compressor and fans work hard to pull the temperature back down. Quick, decisive door openings keep those louder stretches short.

When to stop troubleshooting and call a technician

Some noises arrive with signs that no amount of leveling or vacuuming will fix. On Classic (BI) units, the display can show fan fault codes: 35 F 33 and 35 F 34 point to the freezer evaporator fan, and 35 r 34 to the refrigerator evaporator fan, and Sub-Zero's advice is to switch the breaker off for 30 seconds, restore power, and call for service if the fault comes back. Temperature tells you a lot as well: according to Sub-Zero, a fridge dialed to 38 that still reads above 48 degrees will rarely come back just because the condenser got cleaned, so that combination means calling rather than cleaning. A noise that began suddenly and keeps getting louder, a hot or burning smell near the grille, or a compressor that clicks on and off within seconds all deserve a professional look before a small fault turns into a sealed system repair. Owners in Leucadia, Old Encinitas, Olivenhain and across Encinitas can reach Encinitas Sub-Zero Experts at (858) 779-0698, or first read more about what is making the noise in a built-in refrigerator.