Verdict: False. The FDA notes that few refrigerator controls show actual temperatures, so a "3" or a "5" on a dial is a setting, not a reading; only a thermometer tells you whether the fridge is at 40°F or below.
Where the idea comes from
Numbers look like measurements. A dial marked 1 through 9 resembles an oven knob or a thermostat, and people naturally assume a higher or lower number means a particular temperature. Digital displays add to the confusion by showing a number in degrees, which many people read as a live measurement of the food.
What the evidence says
The FDA's guide to refrigerator thermometers is clear on the targets: keep the refrigerator at 40°F or below and the freezer at 0°F. It then explains why the controls can't be trusted to confirm that: "few refrigerator controls show actual temperatures." Its recommendation is a freestanding appliance thermometer, one for the fridge and one for the freezer, checked often, with the settings adjusted as needed.
The FDA also ties thermometers to power outages. After power returns, it advises checking the thermometers before deciding what food to keep.
On a dial control, the numbers are positions on a scale. Which end is colder varies by model, so the manual or the label near the dial is the place to check.
What to do instead
- Put an appliance thermometer in a glass of water on a middle shelf of the fridge, and another between packages in the freezer.
- Leave the doors closed for several hours, or overnight, then read them.
- If the fridge reads above 40°F, move the control one step colder. If the freezer reads above 0°F, adjust it the same way.
- Wait several hours after each change before reading again. Refrigerators respond slowly.
- Write down the setting that holds 40°F or a little below, so you can return to it after cleaning or defrosting.
Exceptions worth knowing
- •Some fridges have linked controls. On many models, the freezer and fresh-food settings affect each other, and the manual explains the order to adjust them.
- •Hot weather can shift things. A fridge in a warm garage or a kitchen during an LA heat wave may need a colder setting to hold the same temperature.
- •Frozen milk or lettuce suggests the setting is too cold or food is blocking a vent.
- •A fridge that won't reach 40°F on its coldest setting needs a diagnosis, not more turning of the dial. See how long frozen food stays safe while you sort it out.
Sources
- •FDA: Refrigerator Thermometers, Cold Facts about Food Safety (40°F and 0°F; few controls show actual temperatures; use a thermometer)
The short version: A dial number is a position on a scale, and only a thermometer can tell you the fridge is at 40°F.
No setting brings your fridge down to 40°F? Call TrueFix Los Angeles at (213) 787-3989. Our technicians cover Hollywood and neighborhoods across the city.