Commercial Freezer Not Freezing: What's Wrong and What to Do

A packed walk-in freezer with the door kept shut often holds product frozen for 24 hours or more; a reach-in or lightly loaded freezer loses that window much faster. If your freezer is holding 15–25 °F instead of 0 °F, keep the door closed, note when it drifted, and get a technician moving — low-temp systems decline fast once they start.

The three usual causes

1. Defrost failure (most common). A freezer coil runs well below freezing, so airborne moisture becomes frost every cycle. The system defrosts several times a day to clear it. When a defrost heater element opens, the timer or control fails, or the termination sensor drifts, frost builds until the coil is a solid block, airflow stops, and the box warms even though the compressor and charge are fine.

2. Refrigerant undercharge from a leak. Low charge means poor heat transfer and a box that can’t reach set point. The leak has to be found and repaired — see refrigerant leak repair — not topped off.

3. Low-temp compressor losing capacity. A low-temperature compressor works harder than a cooler compressor: bigger pressure ratio, hotter discharge, more stress. As it loses capacity the box holds 10–20 °F, the unit short-cycles, and oil breakdown accelerates the decline. Caught early, it’s a straightforward changeout; ignored, it can burn out and contaminate the system.

What to check now

• Is the evaporator coil iced front to back? That points to defrost.
• Are the evaporator fans running?
• Is the door sealing — or is there a ring of ice on the frame from a failed perimeter heater?
• Is the condenser clean and its fan spinning?

Protecting product

Keep the door shut. If the failure will run long, move product to another freezer or arrange dry ice (about 10 lb per cubic foot of freezer space per day is a rough planning figure). Photograph a thermometer reading, log the time it went out, and keep the invoice and diagnosis for an equipment-breakdown or spoilage claim.

Commercial Refrigeration Oklahoma City takes walk-in freezer emergencies 24/7 across the OKC metro.