Depending on the thickness and composition of the atmosphere, convection may be sufficient to prevent ice buildup. The thing about a tidally locked planet, and

Depending on the thickness and composition of the atmosphere, convection may be sufficient to prevent ice buildup. The thing about a tidally locked planet, and about marginally habitable planets in general, is that whatever the average, there are a wide range of surface conditions and often the spectrum is large enough that some subset of them are habitable.