Start at the floor. Remove the toe kick grille at the bottom front of the refrigerator and look behind it. On most models you will find the condenser coil, a grid of thin metal fins, sometimes with a small fan nearby. This is where the box releases heat. It collects dust, pet hair, and kitchen grease like any other surface in the house, and a dirty coil makes the compressor work longer to hold temperature.
The jobs that are yours
Unplug the unit or switch off its breaker before you touch anything behind the grille. Use a soft brush or the brush attachment on a vacuum to lift loose debris from the fins. Go gently. Bent fins restrict airflow, so skip any metal tool and any stiff brush that flattens them. If the cabinet has a drip pan you can reach without moving the unit far, wipe it out. Keep water away from electrical parts.
Inside, wipe the door gasket with mild soap and warm water, then dry it. Check that the door seals by closing it on a sheet of paper at several points around the frame. If the paper slides out easily at any spot, note the location. Clean the shelves and bins, and check that the unit sits level so the door closes on its own. Finally, confirm there is open space around the sides and back for airflow. The installation guide for your model states the clearance it needs.
Write each of these tasks on a short list with the date you last did it. Future-you will want that record, and so will anyone who helps you later.
The jobs that belong to a technician
The sealed refrigerant circuit is not an owner task. Do not open it, add refrigerant, or cut into its lines. The compressor, the control board, the defrost parts, the internal fan motors, and the thermostat wiring all sit with a technician. So do any water supply connections that involve new valves, new tubing, or a change to the ice maker feed. If the outlet the unit plugs into is loose, scorched, or no longer grounded, the outlet belongs to a licensed electrician, not to the refrigerator.
The line between the two groups is simple. If the job is a brush, a vacuum, a wipe, or a level check, it is yours. If the job touches refrigerant, wiring, a valve, or a sealed part, it is not.
Questions to ask before you book
Ask what licensing or certification applies where you live and whether the person holds it. Ask whether they regularly service the type of refrigerator you own, and whether they can name the parts they would expect to need. Ask what the visit includes, whether any diagnostic charge is separate or credited toward a repair, and whether they will give you a written estimate before work starts. Ask who warrants the repair, for how long, and whether that warranty depends on the owner keeping up any cleaning or visit schedule.
Reading the paper
If the unit came with a manufacturer warranty, a store plan, or a service contract, read the conditions before you rely on any of them. Look for the maintenance conditions, because many require the owner to keep the coil clean and to keep records. Check the waiting period, the exclusions, the cancellation terms, and whether the agreement transfers if you sell the home. Find out who the responsible party is for a claim, since the company that sold the plan and the company that stands behind the warranty are not always the same. Keep the serial number, the purchase record, and any signed service paper together in one folder.
Do not assume a plan covers routine cleaning. Plans are written around failures, and the ordinary upkeep usually stays with the owner.
Deciding what to do
Make a two-column list. In one column, put the owner tasks you will do on a set schedule. In the other, put the technician tasks and the signs that mean you should call. Add a note on when the unit should be planned for replacement. The appliances ranked by typical service life page gives the planning frame used across this index, and the figures there are the ones to compare against your install year.
Keep the owner list where you will see it, keep the technician list with the paperwork, and call for help only when a job crosses from one list to the other.