There is no set answer to this question. A small house with four kids, three dogs, and a cat, will need more frequent filter changes up to once a week. A large house with one person and no pets could go up to six months without needing a filter change. The only way to be sure is to replace your old filter with a new one and check it once a week until the filter is noticeably dirty.

Changing filter is very important for proper performance of your system. Whether it is an air conditioner or furnace filter, my opinion would be to change at least once in 4 to 6 weeks during heating season and for air conditioning it should be at least once in a month by yourself or with the help of professional hvac contractors NJ at http://heatingcontractorsnj.webs.com/.