The major factors that will affect the total cost of your HVAC installation can include:
Type of HVAC System Installed
Size of Unit Needed
Cooling - Heating Capacity Needed
Energy Efficient Levels - SEER or AFUE Ratings
Needing Ductwork Installation - Replacement
Local Labor Costs - Varies by Region
Seasonality - Local Climate Extremities
Read in depth about the details here on each of these cost factors and get an estimate on how much each HVAC system will cost to install in your area.