Please choose the correct ending to complete the given sentence: Home and Garden: [header] How to clean a furnace filter [title] Turn off the furnace. [step] Never remove a furnace filter while the furnace is running. Make sure to switch the furnace off before you begin.

Ending1: [substeps] If the furnace system is working properly, the filter will start in about 60 minutes. If it has not, turn off the electrical switch, and you will begin this task. Ending2: There is usually a handle somewhere near the furnace that can be switched off. [substeps] If you're unsure how to turn off your furnace, contact your landlord or the manufacturer. Ending3: Turn on the furnace unit without removing the filter. [title] Remove the filter plate from the gasket. Ending4: [title] Rinse your furnace filter with water. [step] You can use a scrub brush for this, or you can submerge the filter in water before cleaning the engine.

Answer format: ending1/ending2/ending3/ending4