Where is the cabin air filter in an f250 super duty truck 2009

Hi this is Dusty, I'm one of the auto experts on RepairPal's Car Genius team. Going without air conditioning is never fun! A clogged filter would cause a lack of air flow regardless of the temperature. But replacing it is recommended at regular intervals, check your owner's manual for Ford's maintenance schedule. Given the random performance of the system, I would suspect that you have another issue. Some likely suspects would be intermittent compressor (or the electrical circuit that controls the compressor) failure, or there's a slow leak somewhere in the system. There are other possibilities of course, and some of those repairs can be costly so an accurate diagnosis will save you money in the long run. If you need help finding a reputable, high-quality shop near you, or if you have any questions, give us a call at (877) 913-1554