1. Clean or replace furnace filter. 

2. Check and clean mechanical ventilation system (HRV/ERV). Check your manual and follow manufacturer's recommendations.

3. Clean snow from air intakes, exhausts and meters.

4. Remove excess snow from roof to prevent ice dams

5. Check gutters and downspouts and clean if needed.

6. Inspect basement/crawl space for seepage/leakage.

7. Do safety checks: smoke detectors, fire extinguisher, carbon monoxide alarms, door and window locks.  It's also     helpful to review or establish fire escape routes with your family.

8. Check and repair any damaged screens.

9. Adjust thermostat for season change.

10. Observe humidity levels and adjust the setting on the humidistat or air exchanger controller as needed to eliminate condensation or frost on windows.