The cosmonauts from Soyuz T-13 mission "wore winter garb, including fur-lined hats, as they entered the station." "Frost covered the walls and apparatus. "
Essentially, the heat balance of Salyut 7 was definitely negative, requiring active heating.
Meanwhile, ISS requires active cooling, and a lot of it, suffering from surplus heat, the radiators and cooling systems being absolutely vital to the station's existence.
Would ISS freeze over as well, without power? Or do the two designs differ in some significant way that changes their "ambient" temperature?