Refrigerators and freezers
A fridge that runs but will not cool usually starts with the condenser coils. In apartments, those coils hide underneath or behind the toe grille, matted with dust and pet hair that force the compressor to overwork. Next the tech listens for the evaporator fan behind the freezer panel, because a dead fan leaves a freezer cold and the fresh food side warm. If frost has built up on the evaporator coil, the defrost system is next: heater, defrost thermostat and control board, each checked for continuity with a multimeter. A clicking sound every few minutes with no hum often means a failed start relay or overload on the compressor.
Washers
A washer full of standing water almost always comes down to the drain path. The tech checks the pump filter for socks, coins and hair ties, then tests the drain pump motor itself. If the machine will not start or spin, the lid switch on a top-loader or the door lock assembly on a front-loader is a common culprit. Heavy banging on spin points to suspension trouble: tired shocks, worn springs or a cracked drum spider.
Dryers
No heat in an electric dryer usually means a blown thermal fuse or a burned-out heating element, and no heat in a gas dryer often means a weak igniter or failed gas valve coils. A drum that will not turn points to a snapped belt, and a squeal or thump points to worn rollers or an idler pulley. What people tend to miss is that a thermal fuse fails for a reason, and the reason is usually a blocked vent. In high-rise buildings with long vent runs, a good tech checks airflow at the exhaust before closing out the job.
Dishwashers
Water pooling in the tub starts with a check of the filter and drain hose, then the drain pump. If the unit hums but never fills, the tech tests the water inlet valve and its solenoid. Dishes that come out cold and wet usually mean a failed heating element or high-limit thermostat.
Ranges, ovens and cooktops
When a gas oven clicks without lighting, the hot surface igniter has usually weakened and no longer draws enough current to open the safety valve. The tech confirms that with a clamp meter and may check gas pressure at the regulator with a manometer. Electric ovens that heat unevenly often have a split bake or broil element, and an oven that runs hot or cold usually has a drifting temperature sensor tested against the tech sheet resistance chart.
Microwaves
If the light and turntable work but food stays cold, the magnetron, high-voltage diode or capacitor may be at fault. A totally dead microwave often has a blown internal fuse triggered by a bad door switch. Never open a microwave yourself: the high-voltage capacitor can hold a lethal charge long after the unit is unplugged, and a trained tech discharges it safely before touching anything.
