I have a small Holiday fridge and it is not

frost on the capilary tube is the sign of bad things, usually a resrtiction in the system, or uncondensables such as water or cooked oil,
this is a sealed sytem repair that would require a lic to repair
with is unit, you would need a minimum of an evaporator and system dryer installed
the dryer is the bulb attached between the evap and the cap tube