1. Iced-over evaporator coils — failed defrost system
What it is: Every fridge runs a defrost cycle every 6–12 hours to melt frost off the evaporator coils behind the freezer back wall. When the defrost heater, thermostat, or timer fails, the coils ice into a solid block and airflow stops. Symptom: freezer is cold (or way too cold), fridge is warm, you hear the fan straining, sometimes a knocking sound (fan blade hitting ice). It is the most common cause across every brand.
Fix: With the refrigerator unplugged, pull the freezer back panel, confirm an ice block on the coils, test defrost heater (typically 15–35Ω) and bimetal thermostat for continuity at temp, replace OEM defrost components, force a manual defrost. Verify normal defrost cycle.
Typical all-in: $345–$485 all-in
2. Failed evaporator fan motor
What it is: The evaporator fan behind the freezer back panel circulates cold air into both the freezer and the fresh-food compartment. When the motor seizes, you lose airflow and the fridge warms up first (freezer stays cold for a while because cold air sinks). Symptom: freezer ok, fridge warm, no whooshing sound when you open the freezer. Common across Samsung RF/RS, LG LFX, Whirlpool/KitchenAid French-door, and GE Profile.
Fix: Test the fan motor with the refrigerator unplugged, replace OEM evaporator fan, verify airflow with the freezer door switch held in. Check for ice on the fan shroud — fan failure is often downstream of a defrost failure.
Typical all-in: $325–$465 all-in
3. Stuck damper or door control assembly (French-door, side-by-side)
What it is: On French-door and side-by-side fridges a motorized damper between the freezer and fresh-food compartment opens to let cold air through. When the damper sticks closed or the door control burns out, the freezer cools but the fridge sits at 50–60°F. Symptom: freezer perfect, fridge warm, no airflow from the upper-rear vent in the fresh-food compartment. Whirlpool / KitchenAid / Maytag French-door, Samsung four-door, and LG four-door are the most-frequent service.
Fix: Test damper motor in service mode, replace OEM damper / door-control assembly. Verify the door-flap closes flush and that the air-flow path from freezer evaporator into fridge is clean.
Typical all-in: $285–$425 all-in
4. Condenser coils choked with dust + dead condenser fan
What it is: The condenser coils (under the fridge or behind a rear-bottom panel) shed compressor heat. Dust and pet hair insulate them; the compressor runs hot, the system can't reject heat, and cooling falls off. The condenser fan motor often seizes at the same time. Symptom: cabinet warm to the touch on the sides, compressor runs constantly, both freezer and fridge mildly warm.
Fix: Pull and brush-vacuum the condenser coils, test condenser fan motor, replace OEM fan if seized. Often clears 'not cooling well' without any parts — and prevents a compressor failure down the road.
Typical all-in: $185–$345 all-in (coil clean alone is often $185)
5. LG linear compressor / Samsung inverter compressor failure
What it is: LG linear compressors have failed more often than traditional compressors on some models, commonly somewhere between year 3 and year 8. Symptom: fridge total fail, both compartments warm, usually with no error code. Many US-sold LG units carry a 10-year compressor parts warranty — check your model and serial; if the part is covered, our labor-only price is $385–$575. Samsung digital inverter compressors and inverter boards are a different design and fail differently. See our LG linear compressor page for full coverage.
Fix: Confirm compressor stall with start-test (no current draw, no hum, sometimes audible click). Check LG warranty coverage by serial / build date (the claim is yours to submit to LG), and install an OEM compressor.
Typical all-in: $785–$1,150 all-in out of warranty (labor-only $385–$575 if LG's parts coverage applies)
6. Failed start relay or PTC starter
What it is: A small relay on the side of the compressor energizes the start winding for the first half-second of every cycle. When it fails, the compressor either won't start at all or chatters (clicks every 2–3 minutes as it tries and trips on overload). Symptom: clicking sound, warm fridge, no continuous hum. Common across Whirlpool / KitchenAid / Maytag / Frigidaire / GE — typically a $35 part; the all-in repair is $245–$345, including the $149 trip fee credited toward the repair.
Fix: Replace OEM start relay / PTC starter (model-specific), verify compressor starts and runs continuously, confirm pull-down to setpoint within 6 hours.
Typical all-in: $245–$345 all-in
7. Refrigerant leak — sealed system
What it is: When the sealed refrigerant loop develops a leak (usually a pinhole at an evaporator or condenser braze joint), cooling capacity drops gradually over weeks. Symptom: fridge that used to be cold is slowly losing it, freezer at 15°F instead of 0°F, no frost on the suction line. Sealed-system cost depends on the unit — reasonable on a newer Whirlpool, often a write-off on a 12-year-old basic fridge, and worth repairing on a Sub-Zero.
Fix: Confirm leak with electronic leak detector, evacuate, braze, recharge to factory spec by weight. EPA 608-certified. This work carries our 1-year written warranty.
Typical all-in: $685–$1,650 all-in (sometimes a replace-don't-repair call on basic fridges past year 12)
8. Failed main control board
What it is: If the compressor never gets a run command, the defrost cycle never fires, or the fan never spins despite everything testing good — the main control board has failed. Symptom: erratic temperatures, missing diagnostic codes, components that test good but never see voltage. Common on Samsung RF/RS units past year 5 (moisture corrosion on the back-of-cabinet board) and on GE Profile after surges.
Fix: Verify component-trigger voltage at the board harness in service mode, replace OEM main control, re-enter brand-specific setup mode if required (Samsung Forced-Cooling, LG Test mode).
Typical all-in: $425–$685 all-in
9. Door seal leak / ambient overload (often missed)
What it is: A torn door gasket or a fridge in a 90°F garage in July can cause 'not cooling' that's actually 'cooling but overwhelmed'. Symptom: condensation around the door frame, fridge runs constantly, holds 42–46°F instead of 38°F. Garage fridges are a commonly misdiagnosed case — see our garage-refrigerator winter post for the cold-weather version.
Fix: Dollar-bill test the gasket on all four sides, replace OEM gasket if it pulls free easily, verify ambient is within the unit's rated range (most consumer fridges 55–110°F).
Typical all-in: $245–$365 all-in (gasket only)