Short answer: Press and hold SET for three seconds. When the °C symbol begins to flicker, use the arrow buttons to change the displayed value. Release the buttons when the required value is shown; the manual says the new temperature will then be set.
Before changing the setting
The supplied user’s manual explicitly covers the TEFCOLD GUC70. The controller is an electronic thermostat, and the manual says that defrosting is regulated automatically and that the settings and temperature have already been set at the factory.
The manual describes 0–5°C as the correct temperature for a commercial refrigerator. This guide does not choose a new target temperature for you. The appropriate set point can depend on the food being stored and the operating procedures for your site, so use the value authorised for your operation. Do not confuse the displayed set point with a food-safety check: continue to follow your normal temperature-monitoring and food-safety controls.
Use only the normal front-panel buttons described below. Do not enter an undocumented programming menu or change hidden controller parameters.
Change the GUC70 set point
- Press and hold the SET button for three seconds.
- Wait until the °C symbol begins to flicker on the display. The flashing symbol indicates that the controller is ready for the documented adjustment.
- Use the arrow buttons to adjust the displayed value. The panel description identifies the arrows as the controls that increase or decrease the displayed value in programming mode.
- Release the buttons when the required value is displayed. The manual states that, after the buttons are released, the new temperature will be set.
That release action is the save step in the manufacturer’s procedure. The manual does not tell the operator to press another confirmation button after choosing the value.
The sequence has two visible checkpoints: first, the °C symbol begins to flicker after the three-second SET hold; second, the chosen value is visible before the buttons are released. The manual identifies release—not another confirmation press—as the action that sets the new temperature.
What the buttons and display mean
The SET button is used to display the target set point. During the documented adjustment, the arrow buttons change the displayed value. The °C symbol is the measurement-unit indicator; its flashing state is also identified with programming mode on the panel diagram.
The controller regulates cabinet temperature electronically, but changing the set point does not replace checking the actual stored-product temperature under your site’s food-safety process. The manual provides the general 0–5°C refrigerator range, not a single new set point that this guide can prescribe for every use.
If the setting will not change
Do not hold other button combinations, browse parameter codes or attempt to remove the controller panel.
Contact the dealer immediately if the controller or cabinet is malfunctioning. The manual says repairs should be carried out only by a skilled technician familiar with the product. Stop at the normal front-panel controls: do not open panels, inspect wiring or attempt refrigeration work.
The original sequence is on page 6 of the official TEFCOLD GUC50/GUC70/GUC140 user manual.