The answer to 'how much to replace AC in Chicago' is that the cost to replace a central air conditioning system in Chicago can vary widely depending on several factors. In general, you can expect to pay anywhere from $3,000 to $10,000 or more for a full AC replacement, including the unit, installation, and any necessary ductwork or electrical work.
The exact price will depend on the size of your home, the efficiency rating of the new AC unit, the complexity of the installation, and whether you need to upgrade or replace any other HVAC components. It's important to get quotes from multiple licensed and insured HVAC contractors in your local area to get the best price for your specific needs.