i had a guy giggle and tell me i was crazy because i didnt change filter on a large 50 ton R22 system every year. I was always under the impression not to change filter/dryer unless you opened the system for repaire.

i havent been to school for a long time, maybe they teach something new now? or maybe i slept through that part of the class, it was over 10 years ago so i may have forgot ???