Neglecting to replace the HVAC systems not only puts you in danger of being cold in the middle of a blizzard in Chicago, it also puts the lives of you and your family at stake. That is not something you should gamble with.
Seal cracks in the driveway and foundation walls, and check the sump pump. Finally, if your flooding problem continues then this may be the time to hire outside help. There are professional contractors out there who can waterproof your basement against seepage and flooding.