It doesnt blow air after a while, i opened up to see the filter, noticed its iced behind , what could it be ?

Several possibilities - insufficient air flow across the evaporator core (restricted cabin air filter) .. Incorrect refrigerant charge .. Thermo / pressure cycling switch malfunction .. Condensation drain tube clogged or partially restricted .. Expansion valve malfunction .. Moisture within the system - failure to properly evacuate (vacuum) system before recharging. That’s about all the assistance we can offer here online - the actual culprit can only be discovered via *hands-on* testing / evaluation. Good luck!