usage instructions/manual – Liebherr standalone freezer

I recently purchased a second hand Liebherr stand alone freezer. It is about 10 years old (max). there’s no instruction booklet with it and I don’t understand the three traffic lights on the front which sit next to w small sliding switch. the colours from left to right are amber red green. when I first switched it o it was amber, then after a few hours none of the lights were on (it seems to be workign fine). now the middle, red, light has come on. could anyone tell me what these lights mean or where I could get a manual for this freezer?