If you park under trees your box could be full of leaves which can also lead to condensation buildup and frying your resistor packs. The only other thing I've ran into is the core icing over which will also block air flow. On an '05 you can fix that by repositioning the sensor closer to the core. I put mine at about 1/16 of an inch off the core vs the 1/4"(maybe only 1/8" if honest) from factory. Solved my issues with the icing over and haven't had an issue since.
Since yours isn't cold from the get go it sounds as if the flap is hung up or stuck. Is the air flow restricted or warm
? If airflow is also restricted I'd check for something blocking the flow to the core ergo the flap not opening or debris. The boxes are not always sealed well from the factory letting in who knows what to clog it up.
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Sport Pack, Hard Top, Black Mesh Grills, Cup Air Box, TitanQR, Difflow diffuser, Larini Club Sport Exaust, Rear Panel Delete, RTD Brace w/Nitron Toe Pins, Mono-ball bushings, PRORAD, Reverie CF Side Scoops & CF Splitter, CF door pulls, Odyssey PC680. Filled seams including a custom one piece front paint protection film.