How to adjust the temperature of the old cabinet of Coca-Cola display cabinet

There is a letter on the lower left foot of the glass door of the coke display cabinet: PF seems to have low or unstable voltage. Coke display cabinets may consume a lot of electricity, but its intelligence makes it unnecessary for customers to unplug at all. There is an infrared probe next to the temperature display. In the first two weeks of customer use, it will keep your opening and closing time and sales popularity (please don't put anything in front of the freezer to avoid data errors), and it will automatically enter the silent mode at night, that is, sleep. If you open the door at 8 o'clock in the morning, you will start the cabinet around 6 o'clock to ensure that your cabinet is at 8 o'clock. Coke thinks the best drinking temperature is 3. )