What is the loud humming or rattling from my refrigerator?

Why that is usually the answer

The condenser fan buzzes, rattles or ticks once its blade has collected debris or its bearing has worn, and on an inland property that debris is usually dust and eucalyptus litter pulled straight off the driveway air. The compressor's mounts harden with age and stop absorbing vibration, which arrives in the room as a low hum that carries through cabinetry and, in open plan kitchens with rooms above them, straight up through the structure.

Where it usually turns out to be

The noise itself narrows things down more than people expect. A rattle that changes or stops when you touch the front of the unit is usually loose trim or a panel fastener. A rhythmic tick from behind the lower grille is a fan blade catching something. A low hum that has been building for months is compressor mounts. Gurgling and the occasional soft pop are refrigerant moving and are normal on this equipment. A distinct click every few minutes with no cooling afterward is an electrical control trying to start the compressor and failing, and that one is worth a call the same day rather than at the weekend.

There is a reason noise arrives here before it arrives at the coast. A condenser fan runs to a duty cycle set by how well the coil is rejecting heat, so a coil under a layer of dust makes that fan run considerably longer every day than the designer intended. More running hours means a bearing reaches the end of its life sooner, and the first sign is noise. That makes a new rattle genuinely useful information rather than an annoyance: it is often the earliest warning that the airflow side of the machine needs attention, arriving weeks before the temperature does anything alarming.

If that matches what yours is doing, say so when you call — it decides which parts come on the van.