What is a condenser?

The condenser is where refrigerant gives up the heat it collected inside. It is usually a coil under the cabinet or across the back, and it needs airflow to work. Dust, pet hair and lint blanket it over the years, run times climb, the cabinet sides get hot and cooling suffers — symptoms that mimic a low refrigerant charge almost exactly. Cleaning the coils is cheap, fixes a large share of "not cold enough" calls, and must always precede any refrigerant conversation.