The furnace fan needs to move a set amount of air per ton of air conditioning. Operating the furnace with a plugged filter will slow the air flow and can cause the coil to freeze up. Check the filter monthly and change when required.
Most furnace filters are rated in MERV (minimum efficiency reporting value). The most common residential filter is a 1” pleated MERV 6-10. This filter will allow proper air flow with most furnaces. If a higher MERV rating is needed that a 3” or 4” filter rack could be installed to maintain proper air flow. 1” pleated filters available in hardware stores rated in 1200 microns or above can cause air flow problems with most furnaces
If you need high filtration levels contact us to check air flow requirements for your system.