IFR is different from IMC. Just because you're IFR doesn't mean you'll see a cloud.
A long time ago, I once dispatched with the above defect on a 35C day in a rainy Europe and simply picked a level below the freezing level (Planners gave us FL180 which was 1C lowest enroute - we flew below that). Just because you can't enter icing conditions doesn't mean you can't fly through clouds.