If your product display is fading (or blank) and the temperature is near 0 Celsius degrees (+32 Fahrenheit) this is normal and the display will recover once in room temperature. However, if the display fades in room temperature, it is sign that the product needs a new battery. This may also be tested by pressing light button. If display readings get dimmer when pressing the light button the battery will need replacing.
We recommend that battery replacement be done by an authorized Polar Service during warranty period. For local contact information, fax and telephone numbers, please check Polar distributor list here.