The answer to 'how much to fix system upgrade' depends on several factors, but you can typically expect the cost to range from a few hundred to several thousand dollars. The exact price will depend on the size and complexity of your HVAC system, the type of upgrade or repair needed, the materials and labor required, and your location.
Some common factors that influence the cost include the age and condition of your current system, the energy efficiency of the new components, whether any ductwork or electrical work is required, and the reputation and labor rates of the HVAC contractor you choose. It's important to get multiple quotes from local, reputable HVAC companies to compare prices and find the best value for your home.