Refrigerator Not Cooling? 7 Causes and What to Do Next

Quick diagnostic table

Before reading the deep dive, here’s the fast triage. Find your symptom; the most likely cause is listed first.

The 7 causes, in order of frequency

1. Dirty condenser coils (very common — 30% of calls)

The condenser coils sit at the bottom or back of your refrigerator. They release heat from the refrigerant cycle. When they’re clogged with dust, pet hair, and kitchen grease, the system can’t release heat efficiently — and the inside stays warm despite the compressor running constantly.

How to check: pull the refrigerator out from the wall and remove the back panel or kickplate. If you see a heavy mat of dust and hair, that’s likely your problem.

Fix: professional vacuuming + brushing of the condenser coils. Sub-Zero specifically recommends this every 6-12 months. Cost: $160-$220 in LA.

2. Evaporator fan motor failure (very common — 25% of calls)

The evaporator fan sits in the freezer compartment and circulates cold air into the refrigerator section. If you can hear the compressor running but the fridge isn’t cooling, this fan is often the cause.

How to check: open the freezer compartment and listen carefully. You should hear a quiet fan running. Silence = problem.

Fix: evaporator fan motor replacement. Cost: $220-$380.

3. Defrost system failure

Modern refrigerators run an automatic defrost cycle every 6-12 hours. If the defrost heater, thermostat, or timer fails, frost builds up on the evaporator coil — eventually choking airflow and stopping cooling entirely.

How to check: if the back wall of the freezer is iced over, defrost system is failing.

Fix: typically the defrost heater or defrost thermostat. Cost: $250-$450.

4. Faulty thermostat or temperature control

The thermostat tells the compressor when to run. If it fails open (always reading “warm enough”), the compressor never starts. If it fails closed, the compressor never stops — and may freeze food in the fresh section.

Fix: thermostat replacement. Cost: $180-$320.

5. Sealed-system refrigerant leak

The refrigeration cycle uses sealed-system refrigerant. If there’s a leak, refrigerant level drops and cooling capacity falls progressively over weeks or months. Symptoms: fridge runs constantly but never gets cold; some sections OK and others warm.

Diagnosis requires: EPA-certified technician with electronic leak detector.

Fix: leak repair + refrigerant recharge. Cost: $600-$1,200. On units older than 10-12 years, this often doesn’t make economic sense.

6. Compressor start relay failure

The start relay helps the compressor motor begin a run cycle. When it fails, the compressor may hum but not start, or trip out repeatedly.

Fix: start relay replacement. Cost: $180-$320. A relatively easy fix — often misdiagnosed as compressor failure (which is $800+).

7. Door seal (gasket) failure

If the door gasket is cracked, hardened, or doesn’t form a tight seal, warm room air constantly infiltrates. The fridge runs constantly and may still not maintain temperature in hot weather.

How to check: close the door on a dollar bill. If you can pull it out with no resistance, the seal isn’t sealing.

Fix: gasket replacement. Cost: $200-$420.

When to call us vs DIY

Safe to DIY: vacuuming dust off condenser coils (unplug first!). Checking the door gasket. Listening for the evaporator fan.

Call a technician for: anything involving the sealed system (refrigerant), electrical board diagnosis, compressor work, or anything on a premium brand (Sub-Zero, Wolf, Thermador, Viking) where the wrong part can damage the unit. For sealed-system or premium-brand cooling failures, see our refrigerator repair service — or, before symptoms start, our condenser-coil cleaning guide. Across Westside LA, call (213) 205-2055.

Seeing a refrigerator error code?

If your fridge is displaying a fault code (Er dH, 40 E, F dH, etc.), look it up in our Refrigerator Error Code Database for brand-specific meaning and fix steps.