The compressor hums, the light comes on, and the milk is still 55°F. Most of the time it is not a sealed-system failure. It is dirt, a stuck fan, or a $20 start relay.
SAFETY FIRST: Unplug the fridge before you pull it out or open the rear panel. Do not puncture refrigerant lines. If you smell refrigerant or see oil stains on lines, stop and call a pro.
STEP 0. Check the thermostat and door seals (free, 5 minutes). Confirm the temp control is not on vacation or warm. Close a dollar bill in the door; if it slides out easily, the gasket is leaking cold air.
STEP 1. Clean the condenser coils. Pull the fridge out or remove the toe kick. Vacuum and brush the coils. Dust-clogged coils are the #1 DIY save, often under an hour. Do this every 6–12 months.
STEP 2. Listen for the evaporator fan (freezer section). Open the freezer door, press the door switch, and listen. No fan noise with the compressor running usually means a bad evaporator fan motor or ice blocking it. Defrost with the fridge unplugged if the freezer wall is iced over.
STEP 3. Test the start relay (rear of compressor). Unplug, pull the relay off the compressor pins, and shake it. Loose pellets or a burnt smell means replace it (about $10–25). A cheap multimeter continuity check on the relay and overload is the next step.
CALL A PRO IF: the compressor is dead-silent and hot, you see oil on refrigerant lines, or the unit is still under warranty.
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