All central heating/cooling systems need to have a filter installed. Here are some of the locations they can be found:   Older furnaces Inside the blower compartment of the furnace Filter housing underneath furnace Attic/basement/subfloor systems Central air filtration system – The filter housing is often located next to the furnace on the intake side. 1” filters – The filters are usually in a ceiling air intake grill (check for large grills in the ceiling). New system If it is a new home and you can not find the filter, it is advisable to call us for maintenance so we can assess where the filters are located and how many they are. We will provide you with the system maintenance requirements as part of our service. Call us to set up a maintenance visit!