Unplug the refrigerator if possible, or shut off the power at the breaker box.
Open both refrigerator doors. Remove the two screws securing the base grille if your model is so equipped. Grasp the corner edges of the base grille and gently pull the grille out while pushing in on the top to free it from the spring clips. Close the refrigerator doors.
Position a flashlight so that it shines on the refrigerator coils. Turn on the vacuum and use a nozzle attachment to clean up any loose dust and pet hair or other debris around the coils. Be careful not to damage the delicate cooling fins on the coils as you clean.
Dislodge any dusty deposits sticking to the coil fins while continuing to run the vacuum, using a soft brush and proceeding gently. Clean as far back into and underneath the coils as you can reach without damaging any fins.
Clean the base grille with the vacuum and brush. Reattach the grille by snapping it back into place on the spring clips. Replace the grille screws if so equipped. Plug the refrigerator back in or turn on the power.