For further 187-B control frige and freezer separately?

Why not look for a manual? It'd have been useful if you had given the make as well as the partial model number. There are at least three manufacturers I found with a fridge freezer (or frig if you must) that have the string "187B" in the model number. One is Hotpoint, one is Whirlpool and there's a weird Australian site mentioning Hoshizaki.

Here's a few links that may be useful.

https://hoshizaki.com.au/product/hre-187b-ahd-ml/

https://manualzz.com/doc/3217208/whirlpool-ffp187bp--0--user-manual

https://manualmachine.com/hotpoint/ffp187bp/892033-user-manual/

You might also consider whether the "few years old" appliance was knackered when you got it.

Ohhu
August 2021