How to block air conditioning vents in the winter

Updated February 21, 2017

Air vents on an air conditioning system are installed in the ceiling or the top of a wall to allow the cool air to sink during the summer. During the winter months, these vents can cause air leakage, since the warm air from the heater or furnace rises. This warm air leaks into the air conditioning vent into the attic. To prevent the loss of warm interior air, the air conditioning vents should be blocked off during the winter months.

Locate an air conditioning vent and place a step stool underneath. Climb up on the stool so that you can easily reach the vent.

Locate the metal lever that is located along one edge of the air conditioning vent. Pull or push the lever until it is in the complete opposite direction to close the air vent. Look inside the air vent to make sure the internal slats are all positioned horizontally and block the vent.

Place a magnetic air vent cover on top of the outside of the vent to further block it and prevent additional air leaks. You can buy the covers at any home improvement store.

Repeat the process to block off all other air conditioning vents inside the home.


Make sure to remove all magnetic air covers and open the vents before you turn the air conditioning system back on in the warm months.

Things You'll Need

  • Step stool
  • Magnetic vent covers
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About the Author

Kimberly Johnson is a freelance writer whose articles have appeared in various online publications including eHow, Suite101 and Examiner. She has a degree in journalism from the University of Georgia and began writing professionally in 2001.